Income Taxes - Effective Income Tax Rate Reconciliation (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory U.S. federal income tax provision	$ 74	$ 105	$ 100
State income taxes, net of U.S. federal tax benefit	2	3	2
Foreign income tax expense	13	2	4
Change in deferred tax asset valuation allowance	2		3
Tax rate change		(2)	(25)
REIT income not subject to tax	(69)	(92)	(83)
Derecognition and remeasurement of deferred taxes	13	7	(2,347)
Total provision (benefit) for income taxes	$ 35	$ 23	$ (2,346)