Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current taxes:
U.S. federal									$ 15,995	$ 12,256	$ 19,782
State and local									3,624	2,415	1,709
Foreign									4,136	5,778	10,743
Total current tax expense									23,755	20,449	32,234
Deferred taxes:
U.S. federal									(2,252)	1,454	(8,711)
State and local									(759)	493	(265)
Foreign									(3,047)	1,686	1,266
Total deferred tax (benefit) expense									(6,058)	3,633	(7,710)
Total tax expense	$ 6,300	$ 500	$ 6,400	$ 4,600	$ 8,700	$ 10,800	$ 4,500	$ 100	$ 17,697	$ 24,082	$ 24,524