Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Remeasurement of net deferred tax assets due to enactment of Tax Cut and Jobs Act	$ (497)	$ 62,702	$ 0
Excess tax benefits from equity-based compensation	77,478	58,681	$ 0
Estimated federal taxable income	$ 636,849	$ 621,587
Statutory federal income tax rate	21.00%	35.00%	35.00%
Tax benefit from equity benefit plan activity			$ 13,661
Effective tax rate	16.94%	36.53%	35.73%
Unrecognized tax benefits that would affect effective tax rate	$ 34,300
Reversal of accrued interest on unrecognized tax benefits	1,384	$ 1,065	$ 1,582
Total accrued interest on unrecognized tax benefits	17,191	$ 18,575
Reduction in unrecognized tax benefits	$ 11,570