Income Taxes (Income Tax Reconciliation) (Details 3) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
U.S. Federal taxes at statutory rate									$ 85,526	$ 89,561	$ 67,937
State and local taxes, net of U.S. Federal tax									15,366	(4,064)	(1,279)
Stock based compensation									2,048	(1,743)	(1,731)
Other, net									6,982	2,012	1,618
Total provision for income tax	$ 80,800	$ 30,000	$ 41,900	$ (45,400)	$ 39,100	$ 15,200	$ 16,700	$ 27,600	107,300	98,600	52,100
State [Member]
Income Taxes [Line Items]
Valuation allowance against tax benefits									(5,067)	11,632	(15,767)
non-U.S. [Member]
Income Taxes [Line Items]
Valuation allowance against tax benefits									$ 2,445	$ 1,202	$ 1,322