Investment Securities (Summary Of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Investment [Line Items]
Held-to-maturity, fair value	$ 602,355	$ 677,196
Held-to-maturity, Amortized cost	590,950	686,951
Held To Maturity Securities Gross Unrealized Gains Losses 1		0
Held To Maturity Securities Gross Unrealized Losses		39,699
Held-to-maturity, Carrying value	590,950	647,252
Available-for-sale Debt Securities, Amortized Cost Basis	4,430,090	3,819,297
Available-For-Sale Debt Securities, Gross Unrealized Gains, Recognized In O C I	35,140	31,603
Available-For-Sale Debt Securities, Gross Unrealized Losses, Recognized In O C I	167,418	142,275
Available-For-Sale Securities, Debt Securities, Net Carrying Amount	4,297,812
Available-for-sale debt securities, Estimated fair value	4,297,812	3,708,625
Available-for-sale Securities, Gross Unrealized Gain	35,241	31,679
Available-for-sale equity securities, Carrying value		3,708,625
Available-for-sale, Amortized cost	4,583,325	3,955,888
Available-for-sale, Gross unrealized losses, Recognized in OCI	168,064	143,319
Carrying value	4,450,502	3,844,248
Available-for-sale securities, Estimated fair value	4,450,502	3,844,248
Held-to-maturity Securities, Unrecognized Holding Gain		31,411
Held-to-maturity Securities, Unrecognized Holding Loss		1,467
amortized cost of investment securities	5,174,275	4,642,839
Gross Unrealized Gains of Investment Securities Recognized in OCI	47,449	31,679
Gross Unrealized Losses of Investment Securities Recognized in OCI	168,867	183,018
Carrying Value of Investment Securities	5,052,857	4,491,500
Estimated Fair Value of Investment Securities		4,521,444
Municipal Securities [Member]
Investment [Line Items]
Held-to-maturity, fair value		619,889
Held-to-maturity, Amortized cost	590,950	607,675
Held To Maturity Securities Gross Unrealized Gains Losses 1		0
Held To Maturity Securities Gross Unrealized Losses		0
Held-to-maturity, Carrying value	602,355	607,675
Available-for-sale Debt Securities, Amortized Cost Basis	175,017	189,059
Available-For-Sale Debt Securities, Gross Unrealized Gains, Recognized In O C I	1,282	1,143
Available-For-Sale Debt Securities, Gross Unrealized Losses, Recognized In O C I	689	945
Available-For-Sale Securities, Debt Securities, Net Carrying Amount	175,610	189,257
Available-for-sale debt securities, Estimated fair value		189,257
Held-to-maturity Securities, Unrecognized Holding Gain	12,208	13,018
Held-to-maturity Securities, Unrecognized Holding Loss	803	804
Trust Preferred Securities - Banks And Insurance [Member] | Asset-backed Securities [Member]
Investment [Line Items]
Held-to-maturity, fair value		57,307
Held-to-maturity, Amortized cost		79,276
Held To Maturity Securities Gross Unrealized Gains Losses 1		0
Held To Maturity Securities Gross Unrealized Losses		39,699
Held-to-maturity, Carrying value		39,577
Available-for-sale Debt Securities, Amortized Cost Basis	611,836
Available-For-Sale Debt Securities, Gross Unrealized Gains, Recognized In O C I	99	103
Available-For-Sale Debt Securities, Gross Unrealized Losses, Recognized In O C I	150,418	121,984
Available-For-Sale Securities, Debt Securities, Net Carrying Amount	461,517
Available-for-sale equity securities, Carrying value		415,708
Available-for-sale, Amortized cost		537,589
Available-for-sale securities, Estimated fair value		415,708
Held-to-maturity Securities, Unrecognized Holding Gain		18,393
Held-to-maturity Securities, Unrecognized Holding Loss		663
Agency Securities [Member]
Investment [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	631,603	607,523
Available-For-Sale Debt Securities, Gross Unrealized Gains, Recognized In O C I	1,406	1,572
Available-For-Sale Debt Securities, Gross Unrealized Losses, Recognized In O C I	7,139	8,343
Available-For-Sale Securities, Debt Securities, Net Carrying Amount	625,870	600,752
Available-for-sale debt securities, Estimated fair value		600,752
Agency Guaranteed Mortgage-Backed Securities [Member]
Investment [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,417,843	935,164
Available-For-Sale Debt Securities, Gross Unrealized Gains, Recognized In O C I	16,441	12,132
Available-For-Sale Debt Securities, Gross Unrealized Losses, Recognized In O C I	614	2,105
Available-For-Sale Securities, Debt Securities, Net Carrying Amount	1,433,670	945,191
Available-for-sale debt securities, Estimated fair value		945,191
Small Business Administration Loan-Backed Securities [Member]
Investment [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,588,562	1,544,710
Available-For-Sale Debt Securities, Gross Unrealized Gains, Recognized In O C I	15,677	16,446
Available-For-Sale Debt Securities, Gross Unrealized Losses, Recognized In O C I	8,558	8,891
Available-For-Sale Securities, Debt Securities, Net Carrying Amount	1,595,681	1,552,265
Available-for-sale debt securities, Estimated fair value		1,552,265
Auction Rate Securities [Member] | Asset-backed Securities [Member]
Investment [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	5,229
Available-For-Sale Debt Securities, Gross Unrealized Gains, Recognized In O C I	235	207
Available-For-Sale Debt Securities, Gross Unrealized Losses, Recognized In O C I	0	7
Available-For-Sale Securities, Debt Securities, Net Carrying Amount	5,464
Available-for-sale equity securities, Carrying value		5,452
Available-for-sale, Amortized cost		5,252
Available-for-sale securities, Estimated fair value		5,452
Mutual Funds And Other [Member]
Investment [Line Items]
Available-for-sale Securities, Gross Unrealized Gain		76
Available-for-sale, Amortized cost		136,591
Available-for-sale, Gross unrealized losses, Recognized in OCI		1,044
Carrying value		135,623
Available-for-sale securities, Estimated fair value		135,623
Mutual Funds And Stock [Member]
Investment [Line Items]
Available-for-sale Securities, Gross Unrealized Gain	101
Available-for-sale, Amortized cost	153,235
Available-for-sale, Gross unrealized losses, Recognized in OCI	646
Carrying value	$ 152,690