Provision for Federal and Foreign Income Tax Expense for Continuing Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income (loss) before income taxes, U.S.	$ (784,167)	$ 235,571	$ 289,727
Income (loss) before income taxes, Foreign	(143,157)	38,189	21,007
Income (loss) before income taxes	$ (927,324)	$ 273,760	$ 310,734