Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 487	$ 362
Net actuarial gains (losses) of defined benefit plans:
Adjustment, net of taxes	(2)	32
Reclassification to Net income, net of taxes	10	17
Prior service cost of defined benefit plans:
Adjustment, net of taxes	0	(1)
Derivative instrument:
Change in fair value, net of taxes	0	1
Other comprehensive income (loss)	8	49
Total comprehensive income	$ 495	$ 411