Investment Securities (Amortized Cost And Estimated Fair Value By Contractual Maturity Of Investment Securities Available For Sale) (Details) $ in Thousands	Jun. 30, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	$ 69,005
1 to 5 Years, Amortized Cost	62,400
5 to 10 Years, Amortized Cost	1,291,901
More Than 10 years, Amortized Cost	2,092,447
No Stated Maturity, Amortized Cost	6,438
Total, Amortized Cost	3,522,191
Within One Year, Fair Value	69,059
1 to 5 Years, Fair Value	63,684
5 to 10 Years, Fair Value	1,308,032
More Than 10 years, Fair Value	2,127,684
No Stated Maturity, Fair Value	11,900
Total, Fair Value	3,580,359
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	18,758
1 to 5 Years, Amortized Cost	54,983
5 to 10 Years, Amortized Cost	0
More Than 10 years, Amortized Cost	0
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	73,741
Within One Year, Fair Value	18,758
1 to 5 Years, Fair Value	56,065
5 to 10 Years, Fair Value	0
More Than 10 years, Fair Value	0
No Stated Maturity, Fair Value	0
Total, Fair Value	74,823
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	6,613
5 to 10 Years, Amortized Cost	6,393
More Than 10 years, Amortized Cost	0
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	13,006
Within One Year, Fair Value	0
1 to 5 Years, Fair Value	6,800
5 to 10 Years, Fair Value	6,649
More Than 10 years, Fair Value	0
No Stated Maturity, Fair Value	0
Total, Fair Value	13,449
Securities Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	50,063
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	0
Total, Amortized Cost	50,063
Within One Year, Fair Value	50,117
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	0
Total, Fair Value	50,117
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	0
5 to 10 Years, Amortized Cost	16,261
More Than 10 years, Amortized Cost	173,020
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	189,281
Within One Year, Fair Value	0
1 to 5 Years, Fair Value	0
5 to 10 Years, Fair Value	16,653
More Than 10 years, Fair Value	176,130
No Stated Maturity, Fair Value	0
Total, Fair Value	192,783
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	0
1 to 5 Years, Amortized Cost	454
5 to 10 Years, Amortized Cost	1,254,247
More Than 10 years, Amortized Cost	1,289,503
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	2,544,204
Within One Year, Fair Value	0
1 to 5 Years, Fair Value	469
5 to 10 Years, Fair Value	1,269,397
More Than 10 years, Fair Value	1,311,803
No Stated Maturity, Fair Value	0
Total, Fair Value	2,581,669
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	0
5 to 10 Years, Amortized Cost	0
More Than 10 years, Amortized Cost	625,458
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	625,458
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	635,614
No Stated Maturity, Fair Value	0
Total, Fair Value	635,614
State And Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Within One year, Amortized Cost	184
1 to 5 Years, Amortized Cost	350
5 to 10 Years, Amortized Cost	0
More Than 10 years, Amortized Cost	2,466
No Stated Maturity, Amortized Cost	0
Total, Amortized Cost	3,000
Within One Year, Fair Value	184
1 to 5 Years, Fair Value	350
5 to 10 Years, Fair Value	0
More Than 10 years, Fair Value	2,512
No Stated Maturity, Fair Value	0
Total, Fair Value	3,046
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	3,228
Total, Amortized Cost	3,228
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	8,731
Total, Fair Value	8,731
Other Investments [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	15,000
More Than 10 years, Amortized Cost	2,000
No Stated Maturity, Amortized Cost	3,210
Total, Amortized Cost	20,210
Within One Year, Fair Value	0
1 to 5 Years, Fair Value	0
5 to 10 Years, Fair Value	15,333
More Than 10 years, Fair Value	1,625
No Stated Maturity, Fair Value	3,169
Total, Fair Value	$ 20,127