Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Examination [Line Items]
Gross deferred tax asset related to net operating loss carryforwards	$ 4,733,000,000	$ 4,239,000,000
Gross deferred tax asset related to foreign net operating loss carryforwards	1,447,000,000
Gross deferred tax asset related to net U.S. federal operating loss carryforwards	2,746,000,000
Gross deferred tax asset related to net operating loss carryforwards for various U.S. states	540,000,000
Deferred tax asset related to foreign net operating loss carryforwards, net of valuation allowance	110,000,000
Alternative minimum tax credit carryforwards	49,000,000
Other business credit carryforwards	15,000,000
Foreign tax credit carryforwards - Before valuation allowance	$ 3,000,000
Year in which foreign tax credit carryforwards begin to expire	2021
Valuation allowance against net deferred tax assets	$ 4,734,000,000	4,877,000,000
Unrecognized tax benefits that would impact effective income tax rate	7,000,000
Accrued interest and penalties	7,000,000	$ 3,000,000
Minimum
Income Tax Examination [Line Items]
Unrecognized tax benefits decrease reasonably possible	4,000,000
Maximum
Income Tax Examination [Line Items]
Unrecognized tax benefits decrease reasonably possible	$ 11,000,000
Foreign
Income Tax Examination [Line Items]
Operating loss carryforwards expiration date	Jan. 01, 2025
U.S. Federal
Income Tax Examination [Line Items]
Operating loss carryforwards expiration date	Jan. 01, 2034
U.S. State
Income Tax Examination [Line Items]
Operating loss carryforwards expiration date	Jan. 01, 2020