Components of Income Tax Benefit (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Deferred income tax benefit:
U.S. Federal	$ (203)	$ (11,969)
Deferred federal income taxes	(203)	(11,969)
Income tax benefit	$ (203)	$ (11,969)