Commitments And Contingencies (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012 item	Sep. 30, 2011	Sep. 30, 2012 loan item	Sep. 30, 2011	Dec. 31, 2011
Loss Contingencies [Line Items]
Number of non-cancelable operating leases	141		141
Rent expense	$ 4,200,000	$ 4,200,000	$ 12,800,000	$ 12,300,000
Rent income	248,000	286,000	856,000	758,000
Losses in connection with standby letters of credit	0	110,000	0	110,000
Standby letters of credit that expire within one year	28,600,000		28,600,000
Standby letters of credit that expire thereafter	30,100,000		30,100,000
Litigation settlement other company owned stock	4,400,000,000		4,400,000,000
Fair value of guarantee with standby letters of credit	254,000		254,000
Number of loans repurchased due to deficiencies in underwriting or loan documentation			20
Concentration risk, percentage			78.00%		79.00%
Visa Inc [Member]
Loss Contingencies [Line Items]
Other company stock owned shares	468,659		468,659
Conversion ratio from Class B shares into Class A shares			42.06%
Value of the Class A shares	$ 134.28		$ 134.28
Unredeemed Class A equivalent shares owned			$ 26,500,000