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
	Mar. 31, 2012	Mar. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total net gains (losses) included in, Other noninterest expense	$ 63,291	$ 66,751
Municipal Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	17,381	22,289
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	43	169
Total net gains (losses) included in, Fixed income securities gains (losses), net		18
Total net gains (losses) included in, Other comprehensive income (loss)	(40)	(299)
Total net gains (losses) included in, Sales		(895)
Total net gains (losses) included in, Redemptions and paydowns	(275)	(2,225)
Fair value of assets, Ending balance	17,109	19,057
Trust Preferred - Banks And Insurance [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	929,356	1,241,694
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	2,553	1,477
Total net gains (losses) included in, Fixed income securities gains (losses), net	4,552	3,468
Total net gains (losses) included in, Net impairment losses on investment securities	(10,209)	(1,820)
Total net gains (losses) included in, Other comprehensive income (loss)	30,199	(51,041)
Total net gains (losses) included in, Sales		(941)
Total net gains (losses) included in, Redemptions and paydowns	(20,581)	(8,838)
Fair value of assets, Ending balance	935,870	1,183,999
Trust Preferred Securities - Real Estate Investment Trusts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	18,645	19,165
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	40
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)	(2,685)	5,977
Total net gains (losses) included in, Sales		(538)
Fair value of assets, Ending balance	16,000	19,714
Auction Rate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	70,020	109,609
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	1	8
Total net gains (losses) included in, Fixed income securities gains (losses), net	1,888	7
Total net gains (losses) included in, Other comprehensive income (loss)	789	(20)
Total net gains (losses) included in, Sales		(135)
Total net gains (losses) included in, Redemptions and paydowns	(31,825)	(225)
Fair value of assets, Ending balance	40,873	109,244
Other Asset-Backed [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	43,546	69,630
Total net gains (losses) included in, Accretion of purchase discount on securities available-for-sale	80	39
Total net gains (losses) included in, Fixed income securities gains (losses), net	(5,773)	7
Total net gains (losses) included in, Other comprehensive income (loss)	5,314	1,324
Total net gains (losses) included in, Redemptions and paydowns	(2,845)	(1,513)
Fair value of assets, Ending balance	40,322	69,487
Private Equity Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of assets, Beginning balance	128,348	141,690
Total net gains (losses) included in, Dividends and other investment income	1,739	707
Total net gains (losses) included in, Equity securities gains, net	9,461	897
Total net gains (losses) included in, Purchases	2,982	3,333
Total net gains (losses) included in, Sales	(5,654)	(3,277)
Total net gains (losses) included in, Redemptions and paydowns	(2,130)	(803)
Fair value of assets, Ending balance	134,746	142,547
Derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of liabilities, Beginning balance	(5,422)	(15,925)
Total net gains (losses) included in, Redemptions and paydowns	204	5,414
Fair value of liabilities, Ending balance	(5,218)	(10,511)
Other Liabilities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of liabilities, Beginning balance	(86)	(561)
Total net gains (losses) included in, Other noninterest expense	(119)	119
Fair value of liabilities, Ending balance	$ (205)	$ (442)