Other Comprehensive Income (Schedule of Reclassifications from AOCI) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on sale of investment securities	$ 4	$ 269	$ 333	$ 106	$ 0	$ 810	$ 2,537	$ 0	$ 712	$ 3,347	$ 3,823
Income tax expense	(18,755)	(18,158)	(20,835)	(18,922)	(20,261)	(19,489)	(18,312)	(16,603)	(76,670)	(74,665)	(57,951)
Net of tax	43,754	47,305	46,373	42,117	48,526	44,993	41,240	38,938	179,549	173,697	151,379
Total interest expense	(21,827)	(21,766)	(23,032)	(24,287)	(26,274)	(27,326)	(30,255)	(30,739)	(90,912)	(114,594)	(135,955)
Compensation and benefits									(264,835)	(264,101)	(262,647)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Available for sale and transferred securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gain on sale of investment securities									712	3,347	3,823
Impairment loss recognized in earnings									(7,277)	0	0
Income tax expense									2,351	(1,171)	(1,338)
Net of tax									(4,214)	2,176	2,485
Reclassification out of Accumulated Other Comprehensive Income [Member] | Derivative Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense									3,320	2,350	(5,194)
Net of tax									(5,952)	(4,225)	8,548
Total interest expense									(9,272)	(6,575)	13,742
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Pension and Postretirement Benefit Plans [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense									1,161	1,471	167
Net of tax									(2,081)	(2,644)	(298)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Pension and Postretirement Benefit Plans [Member] | Prior Service Cost [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Compensation and benefits									(73)	(73)	(73)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined Benefit Pension and Postretirement Benefit Plans [Member] | Amortization of Gain (loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Compensation and benefits									$ (3,169)	$ (4,042)	$ (392)