Pension and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended		12 Months Ended
	Oct. 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Pension Benefits [Member]	Sep. 30, 2012 Pension Benefits [Member]	Sep. 30, 2013 Pension Benefits [Member]	Sep. 30, 2012 Pension Benefits [Member]	Sep. 30, 2013 Other Postretirement Benefits [Member]	Sep. 30, 2012 Other Postretirement Benefits [Member]	Sep. 30, 2013 Other Postretirement Benefits [Member]	Sep. 30, 2012 Other Postretirement Benefits [Member]	Mar. 31, 2013 Retiree Health Benefits [Member]	Sep. 30, 2013 Retiree Life Insurance Benefits [Member]	Dec. 31, 2012 Retiree Life Insurance Benefits [Member]	Dec. 31, 2012 Retiree Life Insurance Benefits [Member] Scenario, Previously Reported [Member]
Change in benefit obligation [Abstract]
Service cost						$ 1	$ 1	$ 2	$ 2	$ 1	$ 0	$ 1	$ 1
Interest cost						45	50	136	149	3	4	9	12
Amendments														(57)
Components of net pension cost and other postretirement benefits cost tables detail [Abstract]
Service cost						1	1	2	2	1	0	1	1
Interest cost						45	50	136	149	3	4	9	12
Expected long-term return on plan assets						(68)	(69)	(204)	(203)	(1)	0	(1)	0
Amortization of net loss from past experience						19	15	56	45		0		0
Amortization of prior service cost							0		0	0	(3)	(3)	(9)
Curtailment gain							0		0		0	(19)	0
Settlement loss							0		6		0		0
Net pension cost						(3)	(3)	(10)	(1)	3	1	(13)	4
Pension And Other Postretirement Footnote Text Details [Abstract]
Increase (decrease) to postretirement benefits liability adjustment pre-tax		(19)	(12)	(113)	(66)
Increase (decrease) to postretirement benefits liability adjustment after-tax		(12)	(8)	(73)	(44)
Expected pre-tax gains (losses) related to amortization of net prior service cost															4		9
Weighted Average Remaining amortization period for prior service costs																2 years 6 months
Average life expectancy of frozen plan participants															25 years
Domestic qualified pension plan contributions	21			174
Required domestic pension plan contributions	21			64
Voluntary Domestic Pension Plan Contributions				110
Expected plan contributions during remainder of current fiscal year		$ 0		$ 0