Investment Securities (Securities With Unrealized Losses And Length Of Impairment Period) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Investment [Line Items]
Less than 12 months, Fair Value	$ 2,326,948	$ 2,125,723
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	15,806	5,488
12 months or longer, Fair Value	852,554	1,137,135
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	25,881	29,896
Total, Fair Value	3,179,502	3,262,858
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	41,687	35,384
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	24,495	90,261
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	482	818
12 months or longer, Fair Value	31,984	32,077
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3,870	4,206
Total, Fair Value	56,479	122,338
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	4,352	5,024
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	193,644	224,808
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	882	922
12 months or longer, Fair Value	157,187	224,779
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,349	7,118
Total, Fair Value	350,831	449,587
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	6,231	8,040
State And Municipal Obligations [Member]
Investment [Line Items]
Less than 12 months, Fair Value	515,521	172,980
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	5,907	646
12 months or longer, Fair Value	124,227	215,702
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	7,276	7,708
Total, Fair Value	639,748	388,682
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	13,183	8,354
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	214,715	55,128
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,417	429
12 months or longer, Fair Value	315,002	381,617
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,338	5,163
Total, Fair Value	529,717	436,745
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	6,755	5,592
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	369,784	141,655
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,861	609
12 months or longer, Fair Value	54,265	43,659
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	394	619
Total, Fair Value	424,049	185,314
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,255	1,228
Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	806,300	1,424,457
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,259	2,009
12 months or longer, Fair Value	144,478	159,098
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,550	3,094
Total, Fair Value	950,778	1,583,555
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	3,809	5,103
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	1,390,799	1,621,240
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4,537	3,047
12 months or longer, Fair Value	513,745	584,374
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	8,282	8,876
Total, Fair Value	1,904,544	2,205,614
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	12,819	11,923
Debt Securities [Member]
Investment [Line Items]
Less than 12 months, Fair Value	202,489	16,434
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3,998	55
12 months or longer, Fair Value	25,411	80,203
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,104	1,988
Total, Fair Value	227,900	96,637
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 5,102	$ 2,043