Schedule II - Valuation and Qualifying Accounts and Allowances (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
of Period		$ 108		$ 106	$ 84
Expense		48		32	102
Additions		(1)		(4)	(12)
Reductions (a)	[1]	(42)		(26)	(68)
Period		113		108	106
Valuation allowance on deferred tax assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
of Period		732		554	317
Expense		159		222	264
Additions		0		0	0
Reductions (a)		(23)	[2]	(44)	(27)
Period		$ 868		$ 732	$ 554

[1] Includes write-offs and amounts reclassified to assets held for sale.

[2] Other reductions in 2015 for valuation allowance on deferred taxes primarily due to currency translation.