Income Taxes - Components of Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal									$ 85,371	$ 79,596	$ 56,064
Foreign									9,796	10,832	9,798
State and Local									14,955	18,832	14,795
Total Current									110,122	109,260	80,657
Deferred:
Federal									150,800	11,510	(1,196)
Foreign									(3,464)	(1,439)	659
State and Local									984	(28)	(3,090)
Total Deferred									148,320	10,043	(3,627)
Total	$ 188,876	$ 28,815	$ 22,459	$ 18,292	$ 39,913	$ 38,980	$ 30,676	$ 9,734	$ 258,442	$ 119,303	$ 77,030