Accumulated Other Comprehensive Income (Loss) - Parenthetical (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Equity [Abstract]
Tax (benefit) expense included in net unrealized gains (losses)	$ (44)	$ (13)	$ 157	$ (468)
Tax included in reclassification	(10)	(14)	(16)	(75)
Tax included in amortization (less than $1 for the three months ended September 30, 2014)	1	0	0	0
Other than Temporary impairment losses, Tax (benefit)	0	0	0	(48)
Tax included in reclassification	4	1	7	1
Tax (benefit) expense included in net unrealized gains (losses)	(4)	14	(28)	63
Tax included in reclassification (less than $1 for the three months ended September 30, 2014)	1	1	2	4
Tax (benefit) included in change in unfunded pension postretirement liability (less than $1 for the nine month periods ended September 30, 2014 and 2013)	0	1	0	1
Net pretax unrealized losses on transfers from available-for-sale to held-to maturity securities	$ 234		$ 234