Equity (Details 4) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant amounts reclassified out of each component of AOCI
Preferred stock authorized (in shares)	200,000,000
Preferred stock par value (in dollars per share)	$ 0.01
Preferred stock issued (in shares)	0
Preferred stock outstanding (in shares)	0
Accumulated Defined Benefit Plans Adjustment | Reclassification Out Of Accumulated Other Comprehensive Income
Significant amounts reclassified out of each component of AOCI
Amortization of actuarial losses and other	$ 129	$ 66	$ 114
Less tax benefit	(46)	(20)	(35)
Total reclassification, net of tax	83	46	$ 79
Accumulated Net Gain Loss From Designated Or Qualifying Cash Flow Hedges | Reclassification Out Of Accumulated Other Comprehensive Income
Significant amounts reclassified out of each component of AOCI
(Gains) losses on designated cash flow hedges	265	(79)
Less tax expense	(6)	2
Total reclassification, net of tax	$ 259	$ (77)