Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Investment [Line Items]
Less than 12 months, Fair Value	$ 1,003,618	$ 1,398,179
Less than 12 months, Unrealized Losses	7,713	6,971
12 months or longer, Fair Value	255,705	317,003
12 months or longer, Unrealized Losses	21,291	18,929
Total, Fair Value	1,259,323	1,715,182
Total, Unrealized Losses	29,004	25,900
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	82,149
Less than 12 months, Unrealized Losses	768
Total, Fair Value	82,149
Total, Unrealized Losses	768
State And Municipal Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	148,038	65,962
Less than 12 months, Unrealized Losses	1,582	712
12 months or longer, Fair Value	87,350	110,807
12 months or longer, Unrealized Losses	16,268	10,507
Total, Fair Value	235,388	176,769
Total, Unrealized Losses	17,850	11,219
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	60,464	72,019
Less than 12 months, Unrealized Losses	351	493
Total, Fair Value	60,464	72,019
Total, Unrealized Losses	351	493
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	4,602	23,672
Less than 12 months, Unrealized Losses	115	784
12 months or longer, Fair Value	72,198	118,972
12 months or longer, Unrealized Losses	3,327	7,028
Total, Fair Value	76,800	142,644
Total, Unrealized Losses	3,442	7,812
Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	708,365	1,236,526
Less than 12 months, Unrealized Losses	4,897	4,982
12 months or longer, Fair Value	96,157	87,224
12 months or longer, Unrealized Losses	1,696	1,394
Total, Fair Value	804,522	1,323,750
Total, Unrealized Losses	6,593	6,376
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	773,431	1,332,217
Less than 12 months, Unrealized Losses	5,363	6,259
12 months or longer, Fair Value	168,355	206,196
12 months or longer, Unrealized Losses	5,023	8,422
Total, Fair Value	941,786	1,538,413
Total, Unrealized Losses	$ 10,386	$ 14,681