Summary of Operating Loss, Capital Loss and General Business Credit Carryforwards (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
U.S. Federal
Income Taxes [Line Items]
Net operating loss	$ 487
Net operating losses, Expiration	None
U.S. State
Income Taxes [Line Items]
Net operating loss	$ 827
Net operating losses, Expiration	Various
Foreign Tax Authority | Brazil
Income Taxes [Line Items]
Net operating loss	$ 14
Net operating losses, Expiration	None
Foreign Tax Authority | Canada
Income Taxes [Line Items]
Net operating loss	$ 20
Net operating losses, Expiration	Through 2040
Capital Loss Carryover | U.S. Federal and State
Income Taxes [Line Items]
Tax credit carryforward, amount	$ 37
Net operating losses, Expiration	2023
Capital Loss Carryover | Foreign Tax Authority | Canada
Income Taxes [Line Items]
Tax credit carryforward, amount	$ 5
Net operating losses, Expiration	None
General business credit | U.S. Federal
Income Taxes [Line Items]
Tax credit carryforward, amount	$ 1
Net operating losses, Expiration	Through 2040