Fair Values Of Assets And Liabilities (Narrative) (Detail) (USD $)										3 Months Ended											3 Months Ended
	Sep. 30, 2012		Jun. 30, 2012	Dec. 31, 2011		Sep. 30, 2011		Sep. 30, 2012 Municipal Bonds [Member]	Dec. 31, 2011 Municipal Bonds [Member]	Sep. 30, 2012 Other Real Estate Owned [Member]	Sep. 30, 2012 Other Real Estate Owned [Member] Minimum [Member]	Sep. 30, 2012 Other Real Estate Owned [Member] Maximum [Member]	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member]	Sep. 30, 2011 Fair Value, Measurements, Recurring [Member]	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member] Municipal Bonds [Member]	Sep. 30, 2011 Fair Value, Measurements, Recurring [Member] Municipal Bonds [Member]	Sep. 30, 2012 Fair Value, Measurements, Recurring [Member] Equity Securities	Sep. 30, 2011 Fair Value, Measurements, Recurring [Member] Equity Securities	Sep. 30, 2012 Fair Value, Measurements, Nonrecurring [Member]	Jun. 30, 2012 Fair Value, Inputs, Level 3 [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Equity Securities	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Equity Securities Minimum [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Equity Securities Maximum [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Mortgage Servicing Rights	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Mortgage Servicing Rights Minimum [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Mortgage Servicing Rights Maximum [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member] Municipal Bonds [Member]	Sep. 30, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member] Municipal Bonds [Member]	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member] Equity Securities	Sep. 30, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member] Equity Securities	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member] Mortgage Servicing Rights	Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2012 Fair Value [Member]	Sep. 30, 2011 Fair Value [Member]	Sep. 30, 2012 Valued Based On Underlying Collateral [Member]	Sep. 30, 2012 Valued Using Discounted Cash Flow Model [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Secured borrowings-owed to securitization investors	$ 0		$ 360,800,000	$ 600,000,000		$ 600,000,000														$ 0
Available-for-sale securities	1,256,768,000			1,291,797,000		1,267,682,000		99,384,000	60,098,000						99,384,000	62,307,000	40,717,000	43,032,000											35,755,000	25,405,000	22,255,000	30,891,000
Discount rate input										5.40%	0.00%	61.00%									2.25%	2.03%	2.41%	10.22%	10.00%	13.50%
Fair Value Inputs, Prepayment Rate																								22.31%	21.00%	26.00%
Mortgage servicing rights													6,276,000	6,740,000														6,740,000					6,276,000
Remaining contractual principal balance outstanding, mortgage loans held-for-sale																																			537,200,000	200,400,000
Mortgage loans held-for-sale	548,300,000					204,100,000							548,300,000	204,081,000													0	0
Total impaired loans	233,014,000	[1]		226,538,000	[1]	203,570,000	[1]																														148,000,000	85,000,000
Other real estate owned																			67,400,000															67,377,000
Mortgages Held for Sale Past Due 90 Days and Accruing	$ 0					$ 0

[1] Impaired loans are considered by the Company to be non-accrual loans, restructured loans or loans with principal and/or interest at risk, even if the loan is current with all payments of principal and interest.