Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Investment [Line Items]
Less than 12 months, Fair Value	$ 544,737	$ 1,398,179
Less than 12 months, Unrealized Losses	2,564	6,971
12 months or longer, Fair Value	251,951	317,003
12 months or longer, Unrealized Losses	18,304	18,929
Total, Fair Value	796,688	1,715,182
Total, Unrealized Losses	20,868	25,900
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	32,357
Less than 12 months, Unrealized Losses	128
12 months or longer, Fair Value	0
12 months or longer, Unrealized Losses	0
Total, Fair Value	32,357
Total, Unrealized Losses	128
State And Municipal Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	130,356	65,962
Less than 12 months, Unrealized Losses	940	712
12 months or longer, Fair Value	87,238	110,807
12 months or longer, Unrealized Losses	15,292	10,507
Total, Fair Value	217,594	176,769
Total, Unrealized Losses	16,232	11,219
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	7,292	72,019
Less than 12 months, Unrealized Losses	8	493
12 months or longer, Fair Value	19,737	0
12 months or longer, Unrealized Losses	128	0
Total, Fair Value	27,029	72,019
Total, Unrealized Losses	136	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	74,614	118,972
12 months or longer, Unrealized Losses	2,402	7,028
Total, Fair Value	74,614	142,644
Total, Unrealized Losses	2,402	7,812
Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	374,732	1,236,526
Less than 12 months, Unrealized Losses	1,488	4,982
12 months or longer, Fair Value	70,362	87,224
12 months or longer, Unrealized Losses	482	1,394
Total, Fair Value	445,094	1,323,750
Total, Unrealized Losses	1,970	6,376
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	382,024	1,332,217
Less than 12 months, Unrealized Losses	1,496	6,259
12 months or longer, Fair Value	164,713	206,196
12 months or longer, Unrealized Losses	3,012	8,422
Total, Fair Value	546,737	1,538,413
Total, Unrealized Losses	$ 4,508	$ 14,681