Available-For-Sale And Held-To-Maturity Securities (Schedule Of Amortized Cost And Fair Values Of The Available For Sale Securities And Held To Maturity Securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Available-for-sale Securities, Amortized cost	$ 1,329,751		$ 1,204,205
Available-for-sale Securities, Gross unrealized gains	22,269	[1]	18,050	[1]
Available-for-sale Securities, Gross unrealized losses	(4,485)	[1]	(8,114)	[1]
Available-for-sale securities, Estimated fair value	1,347,535		1,214,141
Held-to-maturity Securities, Amortized cost	327,447	[2]	190,484	[2]
Held-to-maturity Securities, Gross unrealized gains	7,123	[1],[2]	3,742	[1],[2]
Held-to-maturity Securities, Gross unrealized losses	(4,737)	[1],[2]	(5,155)	[1],[2]
Held-to-maturity securities, Estimated fair value	329,833	[2]	189,071	[2]
U.S. Government Securities [Member]
Available-for-sale Securities, Amortized cost	1,115		1,105
Available-for-sale Securities, Gross unrealized gains	2	[1]
Available-for-sale Securities, Gross unrealized losses	(1)	[1]	(2)	[1]
Available-for-sale securities, Estimated fair value	1,116		1,103
State And Municipal Securities [Member]
Available-for-sale Securities, Amortized cost	79,351		82,256
Available-for-sale Securities, Gross unrealized gains	4,540	[1]	4,979	[1]
Available-for-sale Securities, Gross unrealized losses	(425)	[1]	(303)	[1]
Available-for-sale securities, Estimated fair value	83,466		86,932
Agency [Member]
Available-for-sale Securities, Amortized cost	457,608		396,952
Available-for-sale Securities, Gross unrealized gains	8,687	[1]	8,469	[1]
Available-for-sale Securities, Gross unrealized losses	(413)	[1]	(759)	[1]
Available-for-sale securities, Estimated fair value	465,882		404,662
Commercial [Member]
Available-for-sale Securities, Amortized cost	283,746		270,677
Available-for-sale Securities, Gross unrealized gains	3,664	[1]	1,811	[1]
Available-for-sale Securities, Gross unrealized losses	(542)	[1]	(978)	[1]
Available-for-sale securities, Estimated fair value	286,868		271,510
Non-Agency [Member]
Available-for-sale Securities, Amortized cost	16,458		17,701
Available-for-sale Securities, Gross unrealized gains	231	[1]	135	[1]
Available-for-sale Securities, Gross unrealized losses			(376)	[1]
Available-for-sale securities, Estimated fair value	16,689		17,460
Corporate Fixed Income Securities [Member]
Available-for-sale Securities, Amortized cost	466,221		409,503
Available-for-sale Securities, Gross unrealized gains	4,647	[1]	2,108	[1]
Available-for-sale Securities, Gross unrealized losses	(2,771)	[1]	(5,626)	[1]
Available-for-sale securities, Estimated fair value	468,097		405,985
Held-to-maturity Securities, Amortized cost	55,519	[2]	55,544	[2]
Held-to-maturity Securities, Gross unrealized gains	56	[1],[2]	56	[1],[2]
Held-to-maturity Securities, Gross unrealized losses	(1,331)	[1],[2]	(2,016)	[1],[2]
Held-to-maturity securities, Estimated fair value	54,244	[2]	53,584	[2]
Asset-Backed Securities [Member]
Available-for-sale Securities, Amortized cost	25,252		26,011
Available-for-sale Securities, Gross unrealized gains	498	[1]	548	[1]
Available-for-sale Securities, Gross unrealized losses	(333)	[1]	(70)	[1]
Available-for-sale securities, Estimated fair value	25,417		26,489
Held-to-maturity Securities, Amortized cost	251,832	[2]	122,148	[2]
Held-to-maturity Securities, Gross unrealized gains	6,221	[1],[2]	2,953	[1],[2]
Held-to-maturity Securities, Gross unrealized losses	(2,681)	[1],[2]	(3,138)	[1],[2]
Held-to-maturity securities, Estimated fair value	255,372	[2]	121,963	[2]
Municipal Auction Rate Securities [Member]
Held-to-maturity Securities, Amortized cost	20,096	[2]	12,792	[2]
Held-to-maturity Securities, Gross unrealized gains	846	[1],[2]	733	[1],[2]
Held-to-maturity Securities, Gross unrealized losses	(725)	[1],[2]	(1)	[1],[2]
Held-to-maturity securities, Estimated fair value	$ 20,217	[2]	$ 13,524	[2]

[1] Unrealized gains/(losses) related to available-for-sale securities are reported in accumulated other comprehensive loss.

[2] Held-to-maturity securities are carried in the consolidated statements of financial condition at amortized cost, and the changes in the value of these securities, other than impairment charges, are not reported on the consolidated financial statements.