Income Taxes - Reconciliation of Income Tax Expense Computed by Applying the United States Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory income tax rate	21.00%	35.00%	35.00%
Computed “expected” tax expense	$ 171,849	$ 251,508	$ 240,400
Increase (decrease) in income taxes resulting from:
Effect of foreign taxes	19,008	(25,374)	0
State income taxes, net of Federal income tax benefit	8,682	12,525	9,759
Nondeductible executive compensation	3,126
Stock compensation expense, net	(3,860)	63	3,629
Enactment of 2017 Tax Act	0	(13,894)	0
Other, net	(266)	3,384	535
Income tax expense	$ 198,539	$ 228,212	$ 254,323