Annual report pursuant to Section 13 and 15(d)

Benefit Plans - Defined Contribution Plan (Details)

v3.8.0.1
Benefit Plans - Defined Contribution Plan (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Retirement Benefits [Abstract]      
Defined Contribution expense $ 13,103 $ 6,864 $ 1,511