Annual report pursuant to Section 13 and 15(d)

Benefit Plans - Change in Benefit Obligation and Plan Assets (Details)

v3.20.4
Benefit Plans - Change in Benefit Obligation and Plan Assets (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
USD ($)
plan
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Number Of Defined Benefit Pension Plans | plan 3    
Eco Services      
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Number Of Defined Benefit Pension Plans | plan 2    
Number Of Retiree Health Plans | plan 1    
PQ Holdings Benefit Plan      
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Number Of Retiree Health Plans | plan 2    
United States | PQ Holdings Benefit Plan      
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Number Of Retiree Health Plans | plan 1    
Foreign | PQ Holdings Benefit Plan      
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Number Of Retiree Health Plans | plan 1    
Defined Benefit Pension Plans      
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Fair value of plan assets at beginning of period $ 316,721    
Fair value of plan assets at end of the period 362,705 $ 316,721  
Defined Benefit Pension Plans | United States      
Defined Benefit Plan, Change in Benefit Obligation      
Benefit obligation at beginning of period 267,392 246,311  
Service cost 769 978 $ 1,019
Interest cost 8,595 10,281 9,599
Participant contributions 0 0  
Plan curtailments 0 (2,795)  
Plan settlements (1,455) (1,669)  
Benefits paid (12,713) (10,862)  
Expenses paid 0 0  
Actuarial (gains) losses 25,894 25,148  
Translation adjustment 0 0  
Benefit obligation at end of the period 288,482 267,392 246,311
Changes in actuarial (gains) losses due to discount rates 26,642 26,604  
Changes in actuarial (gains) losses due to demographic experience 1,261 2,953  
Changes in actuarial (gains) losses due to mortality assumptions (2,009) (4,409)  
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Fair value of plan assets at beginning of period 231,413 195,755  
Actual return on plan assets 41,405 43,116  
Employer contributions 5,187 5,073  
Employee contributions 0 0  
Plan settlements (1,455) (1,669)  
Benefits paid (12,713) (10,862)  
Expenses paid 0 0  
Translation adjustment 0 0  
Fair value of plan assets at end of the period 263,837 231,413 195,755
Funded status of the plans (underfunded) (24,645) (35,979)  
Defined Benefit Plan, Accumulated Benefit Obligation 288,482 266,992  
Defined Benefit Pension Plans | Foreign      
Defined Benefit Plan, Change in Benefit Obligation      
Benefit obligation at beginning of period 101,192 84,435  
Service cost 3,895 3,210 3,104
Interest cost 2,193 2,627 2,637
Participant contributions 574 550  
Plan curtailments (1,603) 0  
Plan settlements (105) (102)  
Benefits paid (1,759) (1,833)  
Expenses paid (353) (328)  
Actuarial (gains) losses 4,664 13,459  
Translation adjustment 6,191 (826)  
Benefit obligation at end of the period 114,889 101,192 84,435
Changes in actuarial (gains) losses due to discount rates 5,981 13,837  
Changes in actuarial (gains) losses due to demographic experience 56 (312)  
Changes in actuarial (gains) losses due to mortality assumptions (1,372) (66)  
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Fair value of plan assets at beginning of period 85,308 74,050  
Actual return on plan assets 6,646 10,564  
Employer contributions 3,348 3,084  
Employee contributions 574 550  
Plan settlements (105) (102)  
Benefits paid (1,759) (1,833)  
Expenses paid (353) (328)  
Translation adjustment 5,209 (677)  
Fair value of plan assets at end of the period 98,868 85,308 74,050
Funded status of the plans (underfunded) (16,021) (15,884)  
Defined Benefit Plan, Accumulated Benefit Obligation 110,605 96,891  
Underfunded and Unfunded Plans      
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Funded status of the plans (underfunded) 53,081 63,514  
Supplemental Retirement Plans      
Defined Benefit Plan, Change in Benefit Obligation      
Benefit obligation at beginning of period 11,652 11,868  
Interest cost 352 465 450
Benefits paid (1,001) (1,045)  
Actuarial (gains) losses 1,412 364  
Benefit obligation at end of the period 12,415 11,652 11,868
Changes in actuarial (gains) losses due to discount rates 871 971  
Changes in actuarial (gains) losses due to demographic experience 234 (281)  
Changes in actuarial (gains) losses due to mortality assumptions 307 (326)  
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Fair value of plan assets at beginning of period 0 0  
Employer contributions 1,001 1,045  
Benefits paid (1,001) (1,045)  
Fair value of plan assets at end of the period 0 0 0
Funded status of the plans (underfunded) (12,415) (11,652)  
Defined Benefit Plan, Accumulated Benefit Obligation 12,415 11,652  
Other Postretirement Benefits Plans      
Defined Benefit Plan, Change in Benefit Obligation      
Benefit obligation at beginning of period 3,452 3,814  
Service cost 0 10 16
Interest cost 99 152 150
Participant contributions 241 253  
Plan amendments 0 (460)  
Benefits paid (658) (751)  
Premiums paid 7 7  
Actuarial (gains) losses 225 412  
Translation adjustment 15 29  
Benefit obligation at end of the period 3,367 3,452 3,814
Changes in actuarial (gains) losses due to discount rates 235 334  
Changes in actuarial (gains) losses due to demographic experience (1) 172  
Changes in actuarial (gains) losses due to mortality assumptions (8) (94)  
Defined Benefit Plan, Change in Fair Value of Plan Assets      
Fair value of plan assets at beginning of period 0 0  
Employer contributions 424 505  
Employee contributions 241 253  
Benefits paid (658) (751)  
Premiums paid 7 7  
Fair value of plan assets at end of the period 0 0 $ 0
Funded status of the plans (underfunded) $ (3,367) $ (3,452)