Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Comprehensive Income [Abstract]
Net income	$ 541	$ 521	$ 393
Net unrealized holding (losses) gains arising during the period	(343)	48	202
Less: Reclassification adjustment for net securities gains included in net income	(1)	(14)	(21)
Change in net unrealized (losses) gains before income taxes	(344)	34	181
Net gain (loss) arising during the period	286	(192)	(176)
Less: Amortization of actuarial net loss	(89)	(62)	(42)
Less: Amortization of prior service cost	(2)	(3)	(3)
Less: Amortization of transition obligation	0	(4)	(4)
Change in defined benefit pension and other postretirement plans adjustment before income taxes	377	(123)	(127)
Net cash flow hedge losses arising during the period	0	0	(2)
Less: Reclassification adjustment for net cash flow hedge gains included in net income	0	0	(1)
Change in net cash flow hedge gains before income taxes	0	0	(3)
Total other comprehensive income (loss) before income taxes	33	(89)	51
Provision (benefit) for income taxes	11	(32)	18
Total other comprehensive income (loss), net of tax	22	(57)	33
Comprehensive Income	$ 563	$ 464	$ 426