Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 47	$ 19	$ 18
Charged to Costs & Expenses	9	32	10
Charged to Other Accounts	0	0	0
Deductions	15	4	9
Balance at End of Period	41	47	19
Deferred Tax Asset Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	346	294	364
Charged to Costs & Expenses	0	0	0
Charged to Other Accounts	99	52	0
Deductions	0	0	70
Balance at End of Period	$ 445	$ 346	$ 294