Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investment [Line Items]
Less than 12 months, Fair Value	$ 155,244	$ 1,398,179
Less than 12 months, Unrealized Losses	822	6,971
12 months or longer, Fair Value	227,335	317,003
12 months or longer, Unrealized Losses	13,784	18,929
Total, Fair Value	382,579	1,715,182
Total, Unrealized Losses	14,606	25,900
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	9,979
Less than 12 months, Unrealized Losses	13
12 months or longer, Fair Value	0
12 months or longer, Unrealized Losses	0
Total, Fair Value	9,979
Total, Unrealized Losses	13
State And Municipal Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	16,548	65,962
Less than 12 months, Unrealized Losses	34	712
12 months or longer, Fair Value	98,242	110,807
12 months or longer, Unrealized Losses	13,087	10,507
Total, Fair Value	114,790	176,769
Total, Unrealized Losses	13,121	11,219
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	6,072	72,019
Less than 12 months, Unrealized Losses	5	493
12 months or longer, Fair Value	19,145	0
12 months or longer, Unrealized Losses	48	0
Total, Fair Value	25,217	72,019
Total, Unrealized Losses	53	493
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	0	23,672
Less than 12 months, Unrealized Losses	0	784
12 months or longer, Fair Value	19,445	118,972
12 months or longer, Unrealized Losses	183	7,028
Total, Fair Value	19,445	142,644
Total, Unrealized Losses	183	7,812
Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	122,645	1,236,526
Less than 12 months, Unrealized Losses	770	4,982
12 months or longer, Fair Value	90,503	87,224
12 months or longer, Unrealized Losses	466	1,394
Total, Fair Value	213,148	1,323,750
Total, Unrealized Losses	1,236	6,376
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	128,717	1,332,217
Less than 12 months, Unrealized Losses	775	6,259
12 months or longer, Fair Value	129,093	206,196
12 months or longer, Unrealized Losses	697	8,422
Total, Fair Value	257,810	1,538,413
Total, Unrealized Losses	$ 1,472	$ 14,681