Income Taxes - Summary of Reconciliation of the Income Tax Benefit (Expense) at the Statutory Income Tax Rate and the Effective Tax Rate for Income before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income before income tax	$ 373,780	$ 1,019,404	$ 293,919
Income tax at the U.S. statutory federal rate (21% in 2019 and 2018 and 35% in 2017)	(78,494)	(214,075)	(102,872)
Decrease (increase) in income tax resulting from:
Foreign rate differential	438	2,643	2,326
State income taxes, net of federal benefit	1,621	(379)
U.S. earnings not subject to federal income tax	85,495	208,472	98,026
Equity investments	1,091	46	(3,293)
Change in valuation allowance	(7,911)	2,668	5,391
Other items, net	381	(302)	(2,259)
Income tax benefit (expense)	$ 2,621	$ (927)	$ (2,681)