Investment Securities (Amortized Cost And Estimated Fair Value By Contractual Maturity Of Investment Securities Available For Sale) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	$ 42,087
1 to 5 Years, Amortized Cost	545,782
5 to 10 Years, Amortized Cost	1,124,016
More Than 10 years, Amortized Cost	1,791,664
No Stated Maturity, Amortized Cost	3,647
Total, Amortized Cost	3,507,196
Within One Year, Fair Value	43,917
1 to 5 Years, Fair Value	550,165
5 to 10 Years, Fair Value	1,136,793
More Than 10 years, Fair Value	1,835,785
No Stated Maturity, Fair Value	3,686
Total, Fair Value	3,570,346
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	200
1 to 5 Years, Amortized Cost	107
5 to 10 Years, Amortized Cost	0
More Than 10 years, Amortized Cost	0
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	307
Within One Year, Fair Value	200
1 to 5 Years, Fair Value	107
5 to 10 Years, Fair Value	0
More Than 10 years, Fair Value	0
No Stated Maturity, Fair Value	0
Total, Fair Value	307
U.S. Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	0
1 to 5 Years, Amortized Cost	272
5 to 10 Years, Amortized Cost	29,969
More Than 10 years, Amortized Cost	6,997
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	37,238
Within One Year, Fair Value	0
1 to 5 Years, Fair Value	272
5 to 10 Years, Fair Value	31,504
More Than 10 years, Fair Value	7,904
No Stated Maturity, Fair Value	0
Total, Fair Value	39,680
Securities Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	37,444
1 to 5 Years, Amortized Cost	521,862
5 to 10 Years, Amortized Cost	0
More Than 10 years, Amortized Cost	0
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	559,306
Within One Year, Fair Value	39,206
1 to 5 Years, Fair Value	525,320
5 to 10 Years, Fair Value	0
More Than 10 years, Fair Value	0
No Stated Maturity, Fair Value	0
Total, Fair Value	564,526
Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	0
1 to 5 Years, Amortized Cost	198
5 to 10 Years, Amortized Cost	182
More Than 10 years, Amortized Cost	272,433
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	272,813
Within One Year, Fair Value	0
1 to 5 Years, Fair Value	208
5 to 10 Years, Fair Value	195
More Than 10 years, Fair Value	279,642
No Stated Maturity, Fair Value	0
Total, Fair Value	280,045
Mortgage-Backed Securities Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	643
1 to 5 Years, Amortized Cost	14,551
5 to 10 Years, Amortized Cost	1,089,339
More Than 10 years, Amortized Cost	901,865
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	2,006,398
Within One Year, Fair Value	676
1 to 5 Years, Fair Value	15,180
5 to 10 Years, Fair Value	1,100,429
More Than 10 years, Fair Value	940,342
No Stated Maturity, Fair Value	0
Total, Fair Value	2,056,627
Collateralized Mortgage-Backed Securities Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	0
1 to 5 Years, Amortized Cost	53
5 to 10 Years, Amortized Cost	0
More Than 10 years, Amortized Cost	602,056
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	602,109
Within One Year, Fair Value	0
1 to 5 Years, Fair Value	53
5 to 10 Years, Fair Value	0
More Than 10 years, Fair Value	600,113
No Stated Maturity, Fair Value	0
Total, Fair Value	600,166
State And Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	2,800
1 to 5 Years, Amortized Cost	8,739
5 to 10 Years, Amortized Cost	4,526
More Than 10 years, Amortized Cost	4,313
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	20,378
Within One Year, Fair Value	2,833
1 to 5 Years, Fair Value	9,025
5 to 10 Years, Fair Value	4,665
More Than 10 years, Fair Value	4,574
No Stated Maturity, Fair Value	0
Total, Fair Value	21,097
Other Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	1,000
1 to 5 Years, Amortized Cost	0
5 to 10 Years, Amortized Cost	0
More Than 10 years, Amortized Cost	4,000
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	5,000
Within One Year, Fair Value	1,002
1 to 5 Years, Fair Value	0
5 to 10 Years, Fair Value	0
More Than 10 years, Fair Value	3,210
No Stated Maturity, Fair Value	0
Total, Fair Value	4,212
Securities With No Stated Maturity (Equity Securities) [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	0
1 to 5 Years, Amortized Cost	0
5 to 10 Years, Amortized Cost	0
More Than 10 years, Amortized Cost	0
No Stated Maturity, Amortized Cost	3,647
Total, Amortized Cost	3,647
Within One Year, Fair Value	0
1 to 5 Years, Fair Value	0
5 to 10 Years, Fair Value	0
More Than 10 years, Fair Value	0
No Stated Maturity, Fair Value	3,686
Total, Fair Value	$ 3,686