Summary of Operations and Significant Accounting Policies - Component of Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Unrealized foreign currency losses	$ (75,706)	$ (36,164)
Unrealized gain on interest rate swap, net of tax	2,317
Unrealized loss on defined benefit plan	$ (39,097)	$ (31,320)