Capital (Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended					9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2011 Net Unrealized Gains (Losses) on Hedging Activities [Member]	Sep. 30, 2012 Net Unrealized Gains (Losses) on Hedging Activities [Member]	Dec. 31, 2011 Net Unrealized Gains (Losses) on Hedging Activities [Member]	Sep. 30, 2012 Pension and Post Retirement Plans [Member]	Sep. 30, 2011 Pension and Post Retirement Plans [Member]	Sep. 30, 2012 Total AOCI [Member]	Sep. 30, 2011 Total AOCI [Member]	Sep. 30, 2012 Held-to-maturity Securities [Member] Noncredit OTTI Gains(Losses) [Member]	Sep. 30, 2011 Held-to-maturity Securities [Member] Noncredit OTTI Gains(Losses) [Member]	Sep. 30, 2012 Available-for-sale Securities [Member] Net Unrealized Gains(Losses) on AFS [Member]	Sep. 30, 2011 Available-for-sale Securities [Member] Net Unrealized Gains(Losses) on AFS [Member]	Sep. 30, 2012 Available-for-sale Securities [Member] Noncredit OTTI Gains(Losses) [Member]	Sep. 30, 2011 Available-for-sale Securities [Member] Noncredit OTTI Gains(Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total AOCI (loss), Beginning of period			$ (162,365)		$ 270	$ 286	$ 286	$ (428)	$ (116)	$ (162,365)	$ (223,341)	$ 0	$ 0	$ 5,891	$ (962)	$ (168,114)	$ (222,533)
Net unrealized gains (losses)										64,153	11,632			29,792	4,186	34,361	7,446
Net change in fair value of OTTI securities	62,497	(12,159)	117,751	47,643						117,751	47,643					117,751	47,643
Noncredit component of OTTI losses	0	0	(662)	(2,697)						(662)	(2,783)	(662)	(2,697)				(86)
Reclassification adjustment of noncredit OTTI losses included in net income	186	6,155	9,495	37,089						9,495	37,089					9,495	37,089
Noncredit OTTI losses transferred from HTM to AFS												662	2,697			(662)	(2,697)
Reclassifications included in net income					18						(7,260)						(7,278)
Pension and post-retirement benefits	29	(4)	54	(12)				54	(12)	54	(12)
Total AOCI (loss), End of period	$ 28,426		$ 28,426		$ 288	$ 286	$ 286	$ (374)	$ (128)	$ 28,426	$ (137,032)	$ 0	$ 0	$ 35,683	$ 3,224	$ (7,169)	$ (140,416)