Income Taxes - Provision for Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current taxes:
U.S. federal									$ 12,256	$ 19,782	$ 34,752
State and local									2,415	1,709	4,747
Foreign									5,778	10,743	7,116
Total current tax expense									20,449	32,234	46,615
Deferred taxes:
U.S. federal									1,454	(8,711)	(15,119)
State and local									493	(265)	(796)
Foreign									1,686	1,266	(2,317)
Total deferred tax (benefit) expense									3,633	(7,710)	(18,232)
Total tax expense	$ 8,700	$ 10,800	$ 4,500	$ 100	$ 5,300	$ 1,200	$ 9,900	$ 8,100	$ 24,082	$ 24,524	$ 28,383