Investment Securities (Amortized Cost And Fair Value Of Available-For-Sale And Held-To-Maturity Investment Securities Portfolio) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale, Amortized Cost	$ 2,155,885	$ 2,030,801
Available-for-sale, Unrealized Gains	75,059	66,067
Available-for-sale, Unrealized Losses	(22,682)	(25,592)
Pooled trust preferred securities, Fair Value	2,208,262	2,071,276	2,202,855
Held-to-maturity, Amortized Cost	463,935	484,590	567,708
Held-to-maturity, Unrealized Gains	29,770	23,287
Held-to-maturity, Unrealized Losses	(1)	(178)
Held-to-maturity, Fair Value	493,704	507,699	574,174
U.S. Treasury [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale, Amortized Cost	15,166	65,221
Available-for-sale, Unrealized Gains	432	548
Available-for-sale, Unrealized Losses	0	0
Pooled trust preferred securities, Fair Value	15,598	65,769
U.S. Government-Sponsored Entities And Agencies [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale, Amortized Cost	345,161	171,629
Available-for-sale, Unrealized Gains	2,183	1,621
Available-for-sale, Unrealized Losses	(55)	(65)
Pooled trust preferred securities, Fair Value	347,289	173,185
Held-to-maturity, Amortized Cost	175,568	177,159
Held-to-maturity, Unrealized Gains	11,662	11,434
Held-to-maturity, Unrealized Losses	0	0
Held-to-maturity, Fair Value	187,230	188,593
Mortgage-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale, Amortized Cost	1,109,721	1,153,629
Available-for-sale, Unrealized Gains	31,384	28,687
Available-for-sale, Unrealized Losses	(163)	(61)
Pooled trust preferred securities, Fair Value	1,140,942	1,182,255
Held-to-maturity, Amortized Cost	69,537	84,075
Held-to-maturity, Unrealized Gains	2,797	3,305
Held-to-maturity, Unrealized Losses	0	0
Held-to-maturity, Fair Value	72,334	87,380
Mortgage-Backed Securities - Non-Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale, Amortized Cost	76,805	90,355
Available-for-sale, Unrealized Gains	514	418
Available-for-sale, Unrealized Losses	(3,572)	(4,873)
Pooled trust preferred securities, Fair Value	73,747	85,900
States And Political Subdivisions [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale, Amortized Cost	431,989	376,609
Available-for-sale, Unrealized Gains	30,604	26,428
Available-for-sale, Unrealized Losses	(528)	(193)
Pooled trust preferred securities, Fair Value	462,065	402,844
Held-to-maturity, Amortized Cost	215,836	216,345
Held-to-maturity, Unrealized Gains	15,311	8,548
Held-to-maturity, Unrealized Losses	(1)	(176)
Held-to-maturity, Fair Value	231,146	224,717
Pooled Trust Preferred Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale, Amortized Cost	25,294	25,461
Available-for-sale, Unrealized Gains	0	0
Available-for-sale, Unrealized Losses	(16,834)	(18,134)
Pooled trust preferred securities, Fair Value	8,460	7,327
Other Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale, Amortized Cost	151,749	147,897
Available-for-sale, Unrealized Gains	9,942	8,365
Available-for-sale, Unrealized Losses	(1,530)	(2,266)
Pooled trust preferred securities, Fair Value	160,161	153,996
Held-to-maturity, Amortized Cost	2,994	7,011
Held-to-maturity, Unrealized Gains	0	0
Held-to-maturity, Unrealized Losses	0	(2)
Held-to-maturity, Fair Value	$ 2,994	$ 7,009