Income Taxes Income Taxes Details 3 (Details) - 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 [Abstract]
Computed tax provision at the applicable federal statutory income tax rate									$ 139,031	$ 97,531	$ 92,764
State and local taxes, net of federal income tax benefits									20,711	20,081	10,146
Foreign jurisdiction differences									2,496	1,646	2,377
Permanent differences associated with dispositions									73	1,288	790
Changes in uncertain tax positions									100	(9,842)	(88,687)
Foreign Valuation Allowance, Amount									(566)	43	(431)
Enactment of US Tax Reform									0	0	(16,105)
Excess tax benefit from share-based compensation									(9,093)	(13,868)	(11,159)
Other									(6,829)	(2,218)	4,479
Provision for income taxes	$ 48,364	$ 37,351	$ 36,170	$ 24,038	$ 47,999	$ 1,997	$ 23,570	$ 21,095	$ 145,923	$ 94,661	$ (5,826)
Total effective tax rate									22.00%	20.40%	(1.30%)