Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current taxes:
U.S. federal									$ 19,392	$ 15,995	$ 12,256
State and local									1,939	3,624	2,415
Foreign									13,245	4,136	5,778
Total current tax expense									34,576	23,755	20,449
Deferred taxes:
U.S. federal									(4,530)	(2,252)	1,454
State and local									(321)	(759)	493
Foreign									(2,606)	(3,047)	1,686
Total deferred tax (benefit) expense									(7,457)	(6,058)	3,633
Total tax expense	$ 8,700	$ 6,100	$ 10,200	$ 2,100	$ 6,300	$ 500	$ 6,400	$ 4,600	$ 27,119	$ 17,697	$ 24,082