Income Taxes - Additional information (Detail) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
	Aug. 28, 2019	Mar. 31, 2019	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Investment impairment		$ 52		$ 52
Income tax expense at U.S. federal statutory rate				21.00%	21.00%	35.00%
Net reduction in income tax expense due to Tax Cuts and Jobs Act					$ (12)	$ (529)
Equity in net losses of unconsolidated entities				$ 55	41	68
Other federal tax credits				11	10	13
Reduction in provision for income taxes due to tax audit settlements			$ 33	$ 2	40	2
Expected time of completion of IRS audits				15 months
Increase (decrease) to accruals and related deferred taxes				$ (22)	(52)	(5)
Reduction in provision for income taxes due to state net operating losses and credits				14	22	12
Excess tax benefits associated with equity-based compensation				25	17	37
Increase (decrease) in provision for income taxes due to impairments				15	1	15
Investments Qualifying for Federal Tax Credits [Member]
Income Taxes
Total consideration	$ 160
Payment to acquire investment	$ 20
Equity in net losses of unconsolidated entities				46	30	30
Income tax (expense) benefit, including tax credits, from equity method investment				96	57	51
Interest expense				$ 9	$ 3	$ 2