Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Investment [Line Items]
Less than 12 months, Fair Value	$ 1,134,254	$ 3,012,123
Less than 12 months, Unrealized Losses	4,047	75,636
12 months or longer, Fair Value	1,296,175	421,202
12 months or longer, Unrealized Losses	45,835	42,542
Total, Fair Value	2,430,429	3,433,325
Total, Unrealized Losses	49,882	118,178
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	47,683	96,172
Less than 12 months, Unrealized Losses	240	243
12 months or longer, Fair Value	31,645	59,677
12 months or longer, Unrealized Losses	4,917	12,901
Total, Fair Value	79,328	155,849
Total, Unrealized Losses	5,157	13,144
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	184,019	487,317
Less than 12 months, Unrealized Losses	849	18,155
12 months or longer, Fair Value	269,271	93,654
12 months or longer, Unrealized Losses	11,009	9,126
Total, Fair Value	453,290	580,971
Total, Unrealized Losses	11,858	27,281
State And Municipal Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	104,018	478,818
Less than 12 months, Unrealized Losses	1,007	15,520
12 months or longer, Fair Value	289,162	178,150
12 months or longer, Unrealized Losses	9,549	17,825
Total, Fair Value	393,180	656,968
Total, Unrealized Losses	10,556	33,345
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	136,246	717,778
Less than 12 months, Unrealized Losses	410	26,124
12 months or longer, Fair Value	385,117	0
12 months or longer, Unrealized Losses	12,588	0
Total, Fair Value	521,363	717,778
Total, Unrealized Losses	12,998	26,124
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	77,052	53,454
Less than 12 months, Unrealized Losses	325	918
12 months or longer, Fair Value	43,537	22,289
12 months or longer, Unrealized Losses	808	702
Total, Fair Value	120,589	75,743
Total, Unrealized Losses	1,133	1,620
Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	572,812	1,088,556
Less than 12 months, Unrealized Losses	1,148	9,072
12 months or longer, Fair Value	194,011	58,398
12 months or longer, Unrealized Losses	4,147	1,097
Total, Fair Value	766,823	1,146,954
Total, Unrealized Losses	5,295	10,169
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	786,110	1,859,788
Less than 12 months, Unrealized Losses	1,883	36,114
12 months or longer, Fair Value	622,665	80,687
12 months or longer, Unrealized Losses	17,543	1,799
Total, Fair Value	1,408,775	1,940,475
Total, Unrealized Losses	19,426	37,913
Debt Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	12,424	90,028
Less than 12 months, Unrealized Losses	68	5,604
12 months or longer, Fair Value	83,432	9,034
12 months or longer, Unrealized Losses	2,817	891
Total, Fair Value	95,856	99,062
Total, Unrealized Losses	$ 2,885	$ 6,495