Benefit Plans - Defined Contribution Plan (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Retirement Benefits [Abstract] | |||
| Defined Contribution expense | $ 13,103 | $ 6,864 | $ 1,511 |
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- References No definition available.
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- Definition Amount of cost for defined contribution plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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