Income Taxes - Balance of Tax Attributes and Their Dates of Expiration (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Significant Tax Attributes And Dates Of Expiration [Line Items]
Net operating loss carryforwards and deduction limitation	$ 572	$ 660
Net capital loss carryforwards	41	41
Undeducted research and development expenditures	145	195
Tax credit carryforwards	99	$ 98
U.S. federal and state
Significant Tax Attributes And Dates Of Expiration [Line Items]
Net capital loss carryforwards	5
U.S. federal
Significant Tax Attributes And Dates Of Expiration [Line Items]
Operating loss carryforwards	1,618
Net operating loss carryforwards and deduction limitation	340
U.S. federal - Indefinite
Significant Tax Attributes And Dates Of Expiration [Line Items]
Operating loss carryforwards	506
Net operating loss carryforwards and deduction limitation	106
U.S. state
Significant Tax Attributes And Dates Of Expiration [Line Items]
Operating loss carryforwards	2,109
Net operating loss carryforwards and deduction limitation	107
Tax credit carryforwards	19
U.S. state - Indefinite
Significant Tax Attributes And Dates Of Expiration [Line Items]
Operating loss carryforwards	253
Net operating loss carryforwards and deduction limitation	8
Canada Federal and Provincial (Excluding Quebec)
Significant Tax Attributes And Dates Of Expiration [Line Items]
Operating loss carryforwards	24
Net operating loss carryforwards and deduction limitation	4
Net capital loss carryforwards	31
Undeducted research and development expenditures	69
Quebec
Significant Tax Attributes And Dates Of Expiration [Line Items]
Operating loss carryforwards	61
Net operating loss carryforwards and deduction limitation	6
Net capital loss carryforwards	5
Undeducted research and development expenditures	76
Other
Significant Tax Attributes And Dates Of Expiration [Line Items]
Net operating loss carryforwards and deduction limitation	1
Net capital loss carryforwards: | U.S. federal and state
Significant Tax Attributes And Dates Of Expiration [Line Items]
Tax credit carryforwards	23
Net capital loss carryforwards: | Canada Federal and Provincial (Excluding Quebec)
Significant Tax Attributes And Dates Of Expiration [Line Items]
Tax credit carryforwards	118
Net capital loss carryforwards: | Quebec
Significant Tax Attributes And Dates Of Expiration [Line Items]
Tax credit carryforwards	54
Undeducted research and development expenditures: | Canada Federal and Provincial (Excluding Quebec)
Significant Tax Attributes And Dates Of Expiration [Line Items]
Tax credit carryforwards	400
Undeducted research and development expenditures: | Quebec
Significant Tax Attributes And Dates Of Expiration [Line Items]
Tax credit carryforwards	843
Undeducted research and development expenditures: | Canadian
Significant Tax Attributes And Dates Of Expiration [Line Items]
Tax credit carryforwards	$ 80