Reclassifications out of Accumulated Other Comprehensive Loss Changes in Accumulated Other Comprehensive Loss by Component (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (3,947)	$ (4,560)
Other comprehensive income (loss) before reclassifications	(303)	384
Amounts reclassified from accumulated other comprehensive income	108	229
Purchase of subsidiary shares from minority interest	(1)
Balance at end of period	(4,143)	(3,947)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(690)	(538)
Other comprehensive income (loss) before reclassifications	(206)	(153)
Amounts reclassified from accumulated other comprehensive income	3	1
Purchase of subsidiary shares from minority interest	(1)
Balance at end of period	(894)	(690)
Unrecognized Net Actuarial Losses and Prior Service Costs
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(3,290)	(4,044)
Other comprehensive income (loss) before reclassifications	(112)	528
Amounts reclassified from accumulated other comprehensive income	105	226
Purchase of subsidiary shares from minority interest	0
Balance at end of period	(3,297)	(3,290)
Deferred Derivative Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(1)	(4)
Other comprehensive income (loss) before reclassifications	13	1
Amounts reclassified from accumulated other comprehensive income	0	2
Purchase of subsidiary shares from minority interest	0
Balance at end of period	12	(1)
Unrealized Investment Gains
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	34	26
Other comprehensive income (loss) before reclassifications	2	8
Amounts reclassified from accumulated other comprehensive income	0	0
Purchase of subsidiary shares from minority interest	0
Balance at end of period	$ 36	$ 34