Investment Securities (Summary Of Available For Sale Investment Securities By Maturity Groupings) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Investment [Line Items]
Amortized Cost	$ 9,258,525		$ 9,012,095
Fair Value	9,522,248		9,224,702
U.S. Government And Federal Agency Obligations [Member]
Investment [Line Items]
Amortized Cost	399,971		328,530
Fair Value	438,759		364,665
Weighted Average Yield	1.23%	[1]
U.S. Government And Federal Agency Obligations [Member] | Maturity After 1 But Within 5 Years [Member]
Investment [Line Items]
Amortized Cost	219,192
Fair Value	241,964
Weighted Average Yield	1.70%	[1]
U.S. Government And Federal Agency Obligations [Member] | Maturity After 5 But Within 10 Years [Member]
Investment [Line Items]
Amortized Cost	107,708
Fair Value	125,331
Weighted Average Yield	1.30%	[1]
U.S. Government And Federal Agency Obligations [Member] | Maturity After 10 Years [Member]
Investment [Line Items]
Amortized Cost	73,071
Fair Value	71,464
Weighted Average Yield	(0.30%)	[1]
Government-sponsored enterprise obligations [Member]
Investment [Line Items]
Amortized Cost	467,063		311,529
Fair Value	471,574		315,698
Weighted Average Yield	1.75%
Government-sponsored enterprise obligations [Member] | Maturity Within 1 Year [Member]
Investment [Line Items]
Amortized Cost	7,473
Fair Value	7,543
Weighted Average Yield	1.13%
Government-sponsored enterprise obligations [Member] | Maturity After 1 But Within 5 Years [Member]
Investment [Line Items]
Amortized Cost	100,794
Fair Value	104,256
Weighted Average Yield	1.79%
Government-sponsored enterprise obligations [Member] | Maturity After 5 But Within 10 Years [Member]
Investment [Line Items]
Amortized Cost	171,805
Fair Value	171,861
Weighted Average Yield	1.59%
Government-sponsored enterprise obligations [Member] | Maturity After 10 Years [Member]
Investment [Line Items]
Amortized Cost	186,991
Fair Value	187,914
Weighted Average Yield	1.90%
State and municipal obligations [Member]
Investment [Line Items]
Amortized Cost	1,585,926		1,220,840
Fair Value	1,615,707		1,245,284
Weighted Average Yield	2.47%
State and municipal obligations [Member] | Maturity Within 1 Year [Member]
Investment [Line Items]
Amortized Cost	89,091
Fair Value	89,899
Weighted Average Yield	2.23%
State and municipal obligations [Member] | Maturity After 1 But Within 5 Years [Member]
Investment [Line Items]
Amortized Cost	681,954
Fair Value	708,271
Weighted Average Yield	2.71%
State and municipal obligations [Member] | Maturity After 5 But Within 10 Years [Member]
Investment [Line Items]
Amortized Cost	537,897
Fair Value	550,026
Weighted Average Yield	2.37%
State and municipal obligations [Member] | Maturity After 10 Years [Member]
Investment [Line Items]
Amortized Cost	276,984
Fair Value	267,511
Weighted Average Yield	2.18%
Agency mortgage-backed securities [Member]
Investment [Line Items]
Amortized Cost	3,248,007		3,989,464
Fair Value	3,380,955		4,106,059
Weighted Average Yield	2.82%
Non-agency mortgage-backed securities [Member]
Investment [Line Items]
Amortized Cost	224,223		315,752
Fair Value	237,011		316,902
Weighted Average Yield	6.08%
Asset-backed securities [Member]
Investment [Line Items]
Amortized Cost	3,152,913		2,692,436
Fair Value	3,167,394		2,693,143
Weighted Average Yield	0.94%
Total mortgage and asset-backed securities [Member]
Investment [Line Items]
Amortized Cost	6,625,143		6,997,652
Fair Value	6,785,360		7,116,104
Weighted Average Yield	2.04%
Other debt securities [Member]
Investment [Line Items]
Amortized Cost	174,727		135,190
Fair Value	177,752		141,260
Other debt securities [Member] | Maturity Within 1 Year [Member]
Investment [Line Items]
Amortized Cost	45,818
Fair Value	47,014
Other debt securities [Member] | Maturity After 1 But Within 5 Years [Member]
Investment [Line Items]
Amortized Cost	41,499
Fair Value	43,121
Other debt securities [Member] | Maturity After 5 But Within 10 Years [Member]
Investment [Line Items]
Amortized Cost	78,468
Fair Value	78,603
Other debt securities [Member] | Maturity After 10 Years [Member]
Investment [Line Items]
Amortized Cost	8,942
Fair Value	9,014
Equity securities [Member]
Investment [Line Items]
Amortized Cost	5,695		18,354
Fair Value	$ 33,096		$ 41,691

[1] Rate does not reflect inflation adjustment on inflation-protected securities