Investment Securities (Summary Of Available For Sale Investment Securities By Maturity Groupings) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Investment [Line Items]
Amortized Cost	$ 9,121,927	$ 8,874,540
Fair Value	9,282,640	8,915,680
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Amortized Cost	497,663	498,226
Fair Value	518,843	505,696
U.S. Government And Federal Agency Obligations [Member] | Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	43,443
Fair Value	44,168
U.S. Government And Federal Agency Obligations [Member] | Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	259,660
Fair Value	276,658
U.S. Government And Federal Agency Obligations [Member] | Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	141,044
Fair Value	147,856
U.S. Government And Federal Agency Obligations [Member] | Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	53,516
Fair Value	50,161
Government-Sponsored Enterprise Obligations [Member]
Investment [Line Items]
Amortized Cost	766,900	766,802
Fair Value	758,229	741,766
Government-Sponsored Enterprise Obligations [Member] | Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	32,831
Fair Value	33,057
Government-Sponsored Enterprise Obligations [Member] | Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	448,512
Fair Value	451,784
Government-Sponsored Enterprise Obligations [Member] | Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	143,551
Fair Value	137,177
Government-Sponsored Enterprise Obligations [Member] | Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	142,006
Fair Value	136,211
State And Municipal Obligations [Member]
Investment [Line Items]
Amortized Cost	1,782,128	1,624,195
Fair Value	1,803,319	1,619,171
State And Municipal Obligations [Member] | Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	167,929
Fair Value	169,519
State And Municipal Obligations [Member] | Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	710,057
Fair Value	734,237
State And Municipal Obligations [Member] | Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	728,853
Fair Value	727,635
State And Municipal Obligations [Member] | Available For Sale Maturity After10 Years [Member]
Investment [Line Items]
Amortized Cost	175,289
Fair Value	171,928
Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	2,726,315	2,743,803
Fair Value	2,795,929	2,772,338
Non-Agency Mortgage-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	289,782	236,595
Fair Value	301,661	246,983
Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	2,914,610	2,847,368
Fair Value	2,920,062	2,844,071
Total Mortgage And Asset-Backed Securities [Member]
Investment [Line Items]
Amortized Cost	5,930,707	5,827,766
Fair Value	6,017,652	5,863,392
Other Debt Securities [Member]
Investment [Line Items]
Amortized Cost	140,335	147,581
Fair Value	138,652	141,757
Other Debt Securities [Member] | Available For Sale Securities Maturity Within1 Year [Member]
Investment [Line Items]
Amortized Cost	11,939
Fair Value	12,012
Other Debt Securities [Member] | Available For Sale Securities Maturity After1 But Within5 Years [Member]
Investment [Line Items]
Amortized Cost	42,329
Fair Value	43,033
Other Debt Securities [Member] | Available For Sale Securities Maturity After5 But Within10 Years [Member]
Investment [Line Items]
Amortized Cost	86,067
Fair Value	83,607
Equity Securities [Member]
Investment [Line Items]
Amortized Cost	4,194	9,970
Fair Value	$ 45,945	$ 43,898