Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 89	$ 99	$ 99
Additions, charged (credited) to income	32	19	18
Additions, charged (credited) to AOCL	0	0	0
Deductions from reserves	(8)	(39)	(20)
Translation adjustment during period	(8)	10	2
Balance at end of period	105	89	99
Valuation allowance — deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	632	2,968	3,393
Additions, charged (credited) to income	31	(2,253)	(206)
Additions, charged (credited) to AOCL	8	(32)	(234)
Deductions from reserves	(4)	0	0
Translation adjustment during period	(46)	(51)	15
Balance at end of period	$ 621	$ 632	$ 2,968