Fair Value (Schedule Of Assets And Liabilities Measured At Fair Value By Class On A Recurring Basis Using Level 3 Inputs) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total net gains (losses) included in, Other noninterest expense	$ 67,648	$ 69,776	$ 198,365	$ 209,300
Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	16,360	18,862	17,381	22,289
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	18	21	82	211
Total net gains (losses) included in, Fixed income securities gains (losses), net		19		37
Total net gains (losses) included in, Other comprehensive income (loss)	136	(530)	(499)	(1,045)
Total net gains (losses) included in, Sales				(895)
Total net gains (losses) included in, Redemptions and paydowns	(200)	(200)	(650)	(2,425)
Fair value of assets, Ending balance	16,323	18,172	16,323	18,172
Trust Preferred - Banks And Insurance [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	926,450	1,097,917	929,356	1,241,694
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	1,239	1,127	6,267	4,017
Total net gains (losses) included in, Fixed income securities gains (losses), net	3,004	11,771	10,780	18,834
Total net gains (losses) included in, Net impairment losses on investment securities	(2,079)	(10,647)	(19,255)	(15,513)
Total net gains (losses) included in, Other comprehensive income (loss)	55,962	(123,705)	89,695	(181,598)
Total net gains (losses) included in, Sales				(72,881)
Total net gains (losses) included in, Redemptions and paydowns	(19,472)	(48,836)	(51,739)	(66,926)
Fair value of assets, Ending balance	965,104	927,627	965,104	927,627
Trust Preferred Securities - Real Estate Investment Trusts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	14,431	19,131	18,645	19,165
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	61		162
Total net gains (losses) included in, Fixed income securities gains (losses), net				(3,605)
Total net gains (losses) included in, Net impairment losses on investment securities				(1,285)
Total net gains (losses) included in, Other comprehensive income (loss)	915	355	(3,400)	5,749
Total net gains (losses) included in, Sales				(538)
Fair value of assets, Ending balance	15,407	19,486	15,407	19,486
Auction Rate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	7,166	91,104	70,020	109,609
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	1	1	3	10
Total net gains (losses) included in, Fixed income securities gains (losses), net		1,018	4,134	1,900
Total net gains (losses) included in, Other comprehensive income (loss)	(4)	(522)	1,331	(583)
Total net gains (losses) included in, Sales				(135)
Total net gains (losses) included in, Redemptions and paydowns	(50)	(20,950)	(68,375)	(40,150)
Fair value of assets, Ending balance	7,113	70,651	7,113	70,651
Other Asset-Backed [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	40,666	45,376	43,546	69,630
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	53	66	213	139
Total net gains (losses) included in, Fixed income securities gains (losses), net	11	10	(5,762)	(6,918)
Total net gains (losses) included in, Net impairment losses on investment securities	(1,919)			(4,031)
Total net gains (losses) included in, Other comprehensive income (loss)	2,418	2,832	8,301	9,232
Total net gains (losses) included in, Sales				(19,310)
Total net gains (losses) included in, Redemptions and paydowns	(2,994)	(2,170)	(6,144)	(4,547)
Fair value of assets, Ending balance	40,154	44,195	40,154	44,195
Private Equity Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	121,488	136,079	128,348	141,690
Total net gains (losses) included in, Dividends and other investment income	5,382	1,735	13,941	7,300
Total net gains (losses) included in, Equity securities gains, net	12,254		11,629	(738)
Total net gains (losses) included in, Purchases	5,659	3,127	13,038	15,926
Total net gains (losses) included in, Sales	(3,548)	(9,331)	(18,266)	(16,617)
Total net gains (losses) included in, Redemptions and paydowns	(12,944)	(1,410)	(20,399)	(17,361)
Fair value of assets, Ending balance	128,291	130,200	128,291	130,200
Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of liabilities, Beginning balance	(5,337)	(5,420)	(5,422)	(15,925)
Total net gains (losses) included, in Redemptions and paydowns, Liabilities	(289)	150	374	10,655
Fair value of liabilities, Ending balance	(5,048)	(5,270)	(5,048)	(5,270)
Other Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of liabilities, Beginning balance	(121)	(442)	(86)	(561)
Total net gains (losses) included in, Other noninterest expense	(7)	384	(42)	503
Fair value of liabilities, Ending balance	$ (128)	$ (58)	$ (128)	$ (58)