Income Taxes - Difference Between Total Tax Expense and Amount Computed by Applying Statutory Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Contingency [Line Items]
Statutory rate applied to income	$ 79,667	$ 180,449	$ 208,874
Plus state income taxes, net of Federal tax benefit	28,658	27,030	33,088
Taxation of foreign operations, net	(9,072)	(17,663)	(7,862)
U.S. tax reform - transition tax	0	4,492	4,875
Non-deductible goodwill impairment tax effect	106,411	0	0
Book tax basis difference in investment	0	0	(11,944)
Valuation allowance	1,995	4,503	20,505
Other	(731)	7,782	(1,395)
Income tax expense, total	215,973	212,808	245,104
Domestic Tax Authority
Income Tax Contingency [Line Items]
Deferred tax remeasurement	0	0	424
Foreign Tax Authority
Income Tax Contingency [Line Items]
Deferred tax remeasurement	$ 9,045	$ 6,215	$ (1,461)