Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Benefit Plan [Line Items]
Defined benefit plan contributions by employer	$ 2,500	$ 2,700	$ 2,600
UNITED KINGDOM
Employee Benefit Plan [Line Items]
Funding valuation period	3 years
Defined benefit plan contributions by employer	$ 868	$ 955
Defined benefit plan estimated employer contributions for 2017	$ 800
Defined benefit plans increase future employer contributions percentage	2.90%