Reclassifications out of Accumulated Other Comprehensive Loss Changes in Accumulated Other Comprehensive Loss by Component (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Changes in Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period	$ (4,560)
Other comprehensive income (loss) before reclassifications	76
Amounts reclassified from accumulated other comprehensive loss	60
Balance at end of period	(4,424)
Foreign Currency Translation Adjustment
Changes in Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period	(538)
Other comprehensive income (loss) before reclassifications	(40)
Amounts reclassified from accumulated other comprehensive loss	1
Balance at end of period	(577)
Unrecognized Net Actuarial Losses and Prior Service Costs
Changes in Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period	(4,044)
Other comprehensive income (loss) before reclassifications	96
Amounts reclassified from accumulated other comprehensive loss	59
Balance at end of period	(3,889)
Deferred Derivative Gains (Losses)
Changes in Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period	(4)
Other comprehensive income (loss) before reclassifications	3
Amounts reclassified from accumulated other comprehensive loss	0
Balance at end of period	(1)
Unrealized Investment Gains
Changes in Accumulated Other Comprehensive Loss [Roll Forward]
Balance at beginning of period	26
Other comprehensive income (loss) before reclassifications	17
Amounts reclassified from accumulated other comprehensive loss	0
Balance at end of period	$ 43