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	Sep. 30, 2013		Dec. 31, 2012
Available-for-sale Securities, Amortized cost	$ 1,236,110		$ 1,601,102
Available for sale securities, unrealized gains	13,608	[1]	27,460	[1]
Available-for-sale Securities, Gross unrealized losses	(18,147)	[1]	(3,394)	[1]
Available-for-sale securities, Estimated fair value	1,231,571		1,625,168
Held-to-maturity Securities, Amortized cost	1,723,482		708,008	[2]
Held-to-maturity Securities, Gross unrealized gains	15,820	[1]	10,776	[1],[2]
Held-to-maturity Securities, Gross unrealized losses	(6,768)	[1]	(3,510)	[1],[2]
Held-to-maturity securities, Estimated fair value	1,732,534		715,274	[2]
U.S. Government Agency Securities [Member]
Available-for-sale Securities, Amortized cost	1,229		1,114
Available for sale securities, unrealized gains		[1]	1	[1]
Available-for-sale Securities, Gross unrealized losses	(3)	[1]	(2)	[1]
Available-for-sale securities, Estimated fair value	1,226		1,113
State And Municipal Securities [Member]
Available-for-sale Securities, Amortized cost	169,799		153,885
Available for sale securities, unrealized gains	1,939	[1]	4,648	[1]
Available-for-sale Securities, Gross unrealized losses	(8,324)	[1]	(1,113)	[1]
Available-for-sale securities, Estimated fair value	163,414		157,420
Agency [Member]
Available-for-sale Securities, Amortized cost	176,024		676,861
Available for sale securities, unrealized gains	2,976	[1]	8,140	[1]
Available-for-sale Securities, Gross unrealized losses	(2,067)	[1]	(153)	[1]
Available-for-sale securities, Estimated fair value	176,933		684,848
Held-to-maturity Securities, Amortized cost	977,514	[2]
Held-to-maturity Securities, Gross unrealized gains	8,006	[1],[2]
Held-to-maturity Securities, Gross unrealized losses	(420)	[1],[2]
Held-to-maturity securities, Estimated fair value	985,100	[2]
Commercial [Member]
Available-for-sale Securities, Amortized cost	229,962		255,255
Available for sale securities, unrealized gains	3,273	[1]	5,902	[1]
Available-for-sale Securities, Gross unrealized losses	(1,526)	[1]	(183)	[1]
Available-for-sale securities, Estimated fair value	231,709		260,974
Held-to-maturity Securities, Amortized cost	59,390	[2]
Held-to-maturity Securities, Gross unrealized gains	87	[1],[2]
Held-to-maturity Securities, Gross unrealized losses		[1],[2]
Held-to-maturity securities, Estimated fair value	59,477	[2]
Non-Agency [Member]
Available-for-sale Securities, Amortized cost	4,746		13,077
Available for sale securities, unrealized gains	92	[1]	801	[1]
Available-for-sale Securities, Gross unrealized losses		[1]
Available-for-sale securities, Estimated fair value	4,838		13,878
Corporate Fixed Income Securities [Member]
Available-for-sale Securities, Amortized cost	498,966		474,338
Available for sale securities, unrealized gains	5,088	[1]	7,590	[1]
Available-for-sale Securities, Gross unrealized losses	(4,088)	[1]	(1,746)	[1]
Available-for-sale securities, Estimated fair value	499,966		480,182
Held-to-maturity Securities, Amortized cost	55,352		55,420	[2]
Held-to-maturity Securities, Gross unrealized gains		[1]	36	[1],[2]
Held-to-maturity Securities, Gross unrealized losses	(2,702)	[1]	(519)	[1],[2]
Held-to-maturity securities, Estimated fair value	52,650		54,937	[2]
Asset-Backed Securities [Member]
Available-for-sale Securities, Amortized cost	155,384		26,572
Available for sale securities, unrealized gains	240	[1]	378	[1]
Available-for-sale Securities, Gross unrealized losses	(2,139)	[1]	(197)	[1]
Available-for-sale securities, Estimated fair value	153,485		26,753
Held-to-maturity Securities, Amortized cost	609,978	[2]	630,279	[2]
Held-to-maturity Securities, Gross unrealized gains	6,704	[1],[2]	9,364	[1],[2]
Held-to-maturity Securities, Gross unrealized losses	(3,646)	[1],[2]	(2,971)	[1],[2]
Held-to-maturity securities, Estimated fair value	613,036	[2]	636,672	[2]
Municipal Auction Rate Securities [Member]
Held-to-maturity Securities, Amortized cost	21,248		22,309	[2]
Held-to-maturity Securities, Gross unrealized gains	1,023	[1]	1,376	[1],[2]
Held-to-maturity Securities, Gross unrealized losses		[1]	(20)	[1],[2]
Held-to-maturity securities, Estimated fair value	$ 22,271		$ 23,665	[2]

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

[2] Held-to-maturity securities are carried at historical cost or at fair value at the time of transfer from the available-for-sale to held-to-maturity category, adjusted for amortization of premiums and accretion of discounts and credit-related other-than-temporary impairment.