Income Taxes - Summary of Net Operating Loss Carryforwards (Detail) $ in Millions	Dec. 31, 2020 USD ($)
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	$ 1,857
Tax Effected NOL	387
Valuation Allowance (VA)	(384)
Tax Effected NOL Net of VA	3
Federal [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	419
Tax Effected NOL	88
Valuation Allowance (VA)	(88)
State [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	305
Tax Effected NOL	17
Valuation Allowance (VA)	(17)
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	1,133
Tax Effected NOL	282
Valuation Allowance (VA)	(279)
Tax Effected NOL Net of VA	3
2020 - 2024 Expiration [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	156
2020 - 2024 Expiration [Member] | Federal [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	6
2020 - 2024 Expiration [Member] | State [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	2
2020 - 2024 Expiration [Member] | Foreign [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	148
2025 - 2039 Expiration [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	776
2025 - 2039 Expiration [Member] | Federal [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	45
2025 - 2039 Expiration [Member] | State [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	303
2025 - 2039 Expiration [Member] | Foreign [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	428
Unlimited Expiration [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	925
Unlimited Expiration [Member] | Federal [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	368
Unlimited Expiration [Member] | Foreign [Member]
Operating Loss Carryforwards [Line Items]
Total Net Operating Loss (NOL)	$ 557