Income Taxes - Computed Amount and Differences in Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Pretax income	$ 528,939	$ 455,273	$ 368,512
Computed amount at statutory rate	111,077	159,346	128,979
State and local income tax (net of federal tax benefit)	8,280	5,841	4,070
Taxes on non-U.S. earnings-net of foreign tax credits	5,725	(24,914)	(6,666)
Global Intangible Lowed-Taxed Income	2,725	0	0
Foreign-Derived Intangible Income Deduction	(5,410)	0	0
Effect of flow-through entities	1,215	192	(8,735)
U.S. business tax credits	(3,056)	(1,928)	(1,665)
Domestic activities production deduction	0	(8,516)	(9,043)
Capital loss on divestitures	0	(2,275)	(23,444)
Share-based payments	(9,348)	(6,844)	(6,520)
Valuation allowance	0	(361)	17,973
Impact of Tax Act	10,298	(100)	0
Other	(3,140)	(2,425)	2,454
Total provision for income taxes	$ 118,366	$ 118,016	$ 97,403

Effect of pass through entities on tax

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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