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
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 105	$ 89	$ 99
Additions, charged (credited) to income	10	32	19
Additions, charged (credited) to AOCL	0	0	0
Deductions from reserves	(13)	(8)	(39)
Translation adjustment during period	(1)	(8)	10
Balance at end of period	101	105	89
Valuation allowance — deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	621	632	2,968
Additions, charged (credited) to income	(309)	31	(2,253)
Additions, charged (credited) to AOCL	2	8	(32)
Deductions from reserves	0	(4)	0
Translation adjustment during period	12	(46)	(51)
Balance at end of period	$ 326	$ 621	$ 632