Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total interest expense	$ 23,032	$ 30,255	$ 47,319	$ 60,994	$ 3,439
Income tax expense	20,835	18,312	39,757	34,915
Net income	46,373	41,240	88,490	80,178
Net gain on sale of investment securities	333	2,537	439	2,537
Compensation and benefits	65,768	63,587	131,818	132,206
Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total interest expense	2,349	1,903	4,908
Derivative Instruments [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Total interest expense	(2,349)	(1,902)	(4,907)	(3,378)
Income tax expense	841	681	1,757	1,209
Net income	(1,508)	(1,221)	(3,150)	(2,169)
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	(119)	(888)	(157)	(888)
Net income	214	1,649	282	1,649
Net gain on sale of investment securities	333	2,537	439	2,537
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	320	336	587	735
Net income	(573)	(604)	(1,053)	(1,318)
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	(875)	(922)	(1,604)	(2,017)
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)	$ (36)	$ (36)