Accumulated Other Comprehensive Loss (Schedule of Accumulated Other Comprehensive Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Impairment loss recognized in earnings	$ (85)	$ 0	$ (246)	$ 0
Income tax expense	(23,679)	(18,158)	(67,795)	(57,915)
Total interest expense	(22,544)	(21,766)	(67,397)	(69,085)
Compensation and benefits	(66,849)	(64,862)	(198,931)	(196,680)
Net income	50,458	47,305	148,737	135,795
Available for sale and transferred securities [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Net gain on sale of investment securities	42	269	4,378	708
Impairment loss recognized in earnings	(85)	0	(246)	0
Income tax expense	7	(96)	(1,488)	(253)
Net income	(36)	173	2,644	455
Derivative Instruments [Member] | Reclassification out of accumualted comprehensive income [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	673	782	2,226	2,540
Total interest expense	(1,853)	(2,182)	(6,189)	(7,090)
Net income	(1,180)	(1,400)	(3,963)	(4,550)
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	36	295	30	882
Net income	(63)	(526)	(53)	(1,579)
Defined benefit pension and postretirement benefit plans [Member] | Reclassification out of accumualted comprehensive income [Member] | Amortization of net loss [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Compensation and benefits	(80)	(803)	(28)	(2,407)
Defined benefit pension and postretirement benefit plans [Member] | Reclassification out of accumualted comprehensive income [Member] | Prior service cost [Member]
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Compensation and benefits	$ (19)	$ (18)	$ (55)	$ (54)