Available-For-Sale Securities (Summary of the Available-for-Sale Securities Portfolio) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 1,785,113		$ 1,284,733
Gross unrealized gains	20,556		22,402
Gross unrealized losses	(9,593)		(15,338)
Total available-for-sale securities, fair value	1,796,076		1,291,797
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	220,226		16,028
Gross unrealized gains	198		145
Gross unrealized losses	(937)		0
Total available-for-sale securities, fair value	219,487		16,173
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	986,186		760,533
Gross unrealized gains	4,839		5,596
Gross unrealized losses	(986)		(213)
Total available-for-sale securities, fair value	990,039		765,916
Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	107,868		57,962
Gross unrealized gains	2,899		2,159
Gross unrealized losses	(296)		(23)
Total available-for-sale securities, fair value	110,471		60,098
Corporate Notes And Other, Financial Issuers [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	142,205		149,229
Gross unrealized gains	2,452		1,914
Gross unrealized losses	(3,982)		(8,499)
Total available-for-sale securities, fair value	140,675		142,644
Corporate Notes And Other, Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,911		27,070
Gross unrealized gains	220		287
Gross unrealized losses	0		(65)
Total available-for-sale securities, fair value	14,131		27,292
Mortgage-Backed, Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	188,485	[1]	206,549	[1]
Gross unrealized gains	8,805	[1]	12,078	[1]
Gross unrealized losses	(30)	[1]	(15)	[1]
Total available-for-sale securities, fair value	197,260	[1]	218,612	[1]
Mortgage-Backed, Non-Agency CMOs [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	73,386	[1]	29,767	[1]
Gross unrealized gains	928	[1]	175	[1]
Gross unrealized losses	0	[1]	(3)	[1]
Total available-for-sale securities, fair value	74,314	[1]	29,939	[1]
Other Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	52,846		37,595
Gross unrealized gains	215		48
Gross unrealized losses	(3,362)		(6,520)
Total available-for-sale securities, fair value	$ 49,699		$ 31,123

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