Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax And Carryforwards [Line Items]
Adjustment of deferred tax (asset) liability		$ (1,200)	$ (82)
Change in tax rate		(797)	(710)
Interest and penalties accrued for unrecognized tax benefits, current period	$ 2	2	2
Interest and penalties accrued for unrecognized tax benefits, total	10	8	5
Unrecognized tax benefits that would impact the effective tax rate	143	145	78
General Business Tax Credit Carryforward
Income Tax And Carryforwards [Line Items]
Operating loss carryforward, amount to expire	82
Federal
Income Tax And Carryforwards [Line Items]
Adjustment of deferred tax (asset) liability		(442)	(569)
Operating loss carryforward	2,500	2,600
State
Income Tax And Carryforwards [Line Items]
Adjustment of deferred tax (asset) liability			$ (42)
Operating loss carryforward	8,600	9,000
Foreign Tax Authority
Income Tax And Carryforwards [Line Items]
Operating loss carryforward	$ 84	$ 91