Income Taxes - Computed Amount and Differences in Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Pretax income	$ 470,340	$ 532,903	$ 528,939
Computed amount at statutory rate	98,771	111,910	111,077
State and local income tax (net of federal tax benefit)	5,954	8,163	8,280
Taxes on non-U.S. earnings-net of foreign tax credits	7,048	5,003	5,725
Global Intangible Low-Taxed Income	(2,731)	2,324	2,725
Foreign-Derived Intangible Income Deduction	(4,928)	(5,811)	(5,410)
Effect of flow-through entities	1,308	1,316	1,215
U.S. business tax credits	(3,163)	(3,193)	(3,056)
Share-based payments	(9,743)	(11,011)	(9,348)
Valuation allowance	70	(117)	0
Impact of Tax Act	0	(334)	10,298
Other	(24)	(868)	(3,140)
Total provision for income taxes	$ 92,562	$ 107,382	$ 118,366