Income Taxes - Summary of Reconciliation of Income Tax Benefit (Expense) from the Statutory Income Tax Rate to the Effective Tax Rate Based on Income before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income before income tax	$ 463,328	$ 373,780	$ 1,019,404
Income tax at the U.S. statutory federal rate (21% in 2020, 2019 and 2018)	(97,299)	(78,494)	(214,075)
Decrease (increase) in income tax resulting from:
Foreign rate differential	2,160	438	2,643
State income taxes, net of federal benefit	970	1,621	(379)
U.S. earnings not subject to federal income tax	82,921	85,495	208,472
Equity investments	380	1,091	46
Change in valuation allowance	(8,514)	(7,911)	2,668
Statutory tax rate change	(9,471)
Other items, net	(2,203)	381	(302)
Income tax benefit (expense)	$ (31,056)	$ 2,621	$ (927)