Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 826	$ 629	$ 1,996	$ 1,651
Net actuarial gains (losses) of defined benefit plans:
Adjustment	28	6	21	86
Recognized within Net income	17	13	38	46
Prior service cost of defined benefit plans:
Adjustment	0	0	0	(2)
Recognized within Net income	(1)	(1)	0	(3)
Derivative instruments:
Change in fair value	0	0	0	(1)
Recognized within Net income	0	0	1	1
Other comprehensive income (loss)	44	18	60	127
Total comprehensive income	$ 870	$ 647	$ 2,056	$ 1,778