Available-For-Sale Securities (Summary Of The Available-For-Sale Securities Portfolio) (Details) (USD $) In Thousands	Sep. 30, 2011		Dec. 31, 2010		Sep. 30, 2010
Amortized Cost	$ 1,249,551		$ 1,491,913
Gross unrealized gains	23,138		17,025
Gross unrealized losses	(5,007)		(12,636)
Fair Value	1,267,682		1,496,302		1,324,179
U.S. Treasury [Member]
Amortized Cost	16,034		104,418
Gross unrealized gains	169
Gross unrealized losses			(8,321)
Fair Value	16,203		96,097		2,015
U.S. Government Agencies [Member]
Amortized Cost	682,221		882,095
Gross unrealized gains	4,959		2,682
Gross unrealized losses	(224)		(722)
Fair Value	686,956		884,055		874,327
Municipal Securities [Member]
Amortized Cost	61,146		51,493
Gross unrealized gains	1,179		896
Gross unrealized losses	(18)		(86)
Fair Value	62,307		52,303		54,641
Corporate Notes And Other, Financial Issuers [Member]
Amortized Cost	160,341		186,931
Gross unrealized gains	2,440		3,048
Gross unrealized losses	(4,638)		(2,972)
Fair Value	158,143		187,007
Corporate Notes And Other, Other [Member]
Amortized Cost	28,221		74,629
Gross unrealized gains	332		330
Gross unrealized losses	(59)		(51)
Fair Value	28,494		74,908
Agency [Member]
Amortized Cost	226,423	[1]	148,693	[1]
Gross unrealized gains	13,638	[1]	9,963	[1]
Gross unrealized losses	(1)	[1]	(3)	[1]
Fair Value	240,060	[1]	158,653	[1]
Non-Agency CMOs [Member]
Amortized Cost	32,182	[1]	3,018	[1]
Gross unrealized gains	312	[1]	10	[1]
Gross unrealized losses	(7)	[1]
Fair Value	32,487	[1]	3,028	[1]
Other Equity Securities [Member]
Amortized Cost	42,983	[1]	40,636	[1]
Gross unrealized gains	109	[1]	96	[1]
Gross unrealized losses	(60)	[1]	(481)	[1]
Fair Value	$ 43,032	[1]	$ 40,251	[1]

[1] Consisting entirely of residential mortgage-backed securities, none of which are subprime.