Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total interest expense	$ 21,766	$ 27,326	$ 69,085	$ 88,320
Income tax expense	18,158	19,489	57,915	54,404
Net gain on sale of investment securities	269	810	708	3,347
Compensation and benefits	64,862	66,126	196,680	198,332
Net income	47,305	44,993	135,795	125,171
Derivative Instruments [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total interest expense	(2,182)	(1,053)	(7,090)	(4,431)
Income tax expense	782	377	2,540	1,586
Net income	(1,400)	(676)	(4,550)	(2,845)
Available for sale and transferred securities [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	(96)	(283)	(253)	(1,171)
Net gain on sale of investment securities	269	810	708	3,347
Net income	173	527	455	2,176
Defined benefit pension and postretirement benefit plans [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	295	368	882	1,103
Net income	(526)	(659)	(1,579)	(1,977)
Amortization of net loss [Member] | Defined benefit pension and postretirement benefit plans [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Compensation and benefits	(803)	(1,009)	(2,407)	(3,026)
Prior service cost [Member] | Defined benefit pension and postretirement benefit plans [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Compensation and benefits	$ (18)	$ (18)	$ (54)	$ (54)