Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 96	$ 117	$ 329
Charged to Costs and Expenses	0	0	0
Charged to Other Accounts	0	0	0
Deductions	6	21	212
Balance at End of Period	90	96	117
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	96	117	329
Charged to Costs and Expenses	0	0	0
Charged to Other Accounts	0	0	0
Deductions	6	21	212
Balance at End of Period	$ 90	$ 96	$ 117