Accumulated Other Comprehensive Loss - Accumulated Other Comprehensive Loss (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ (3,888)	$ (3,557)
Other comprehensive income (loss) before reclassifications	264	291
Amounts reclassified from accumulated other comprehensive loss	263	298
Income taxes	(31)	(23)
Net other comprehensive income (loss)	(32)	(16)
Balance	(3,920)	(3,573)
Unrealized Gains Marketable Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	141
Other comprehensive income (loss) before reclassifications	83
Amounts reclassified from accumulated other comprehensive loss
Income taxes
Net other comprehensive income (loss)	83
Balance	224
Pension and Other Postretirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(3,141)	(2,538)
Other comprehensive income (loss) before reclassifications	(6)	(21)
Amounts reclassified from accumulated other comprehensive loss	215	148
Income taxes	(31)	(23)
Net other comprehensive income (loss)	178	104
Balance	(2,963)	(2,434)
Fair Value of Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	30	(26)
Other comprehensive income (loss) before reclassifications	(104)	(177)
Amounts reclassified from accumulated other comprehensive loss	45	150
Income taxes
Net other comprehensive income (loss)	(59)	(27)
Balance	(29)	(53)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(918)	(993)
Other comprehensive income (loss) before reclassifications	(243)	(93)
Amounts reclassified from accumulated other comprehensive loss	9
Income taxes
Net other comprehensive income (loss)	(234)	(93)
Balance	$ (1,152)	$ (1,086)