Fair Value - Fair Value Measurements (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assumed Gain (Loss) From Loan Sale	$ (2,176)
Interest Rate Movement Effect	4,754
Servicing Rights Value	626
Security Price Change	(4,731)
Total Fair Value Measurement Gain/(Loss)	(1,527)
Mortgage Banking [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Rate lock commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional or Principal Amount	218,933
Assumed Gain (Loss) From Loan Sale	(1,353)
Interest Rate Movement Effect	2,883
Servicing Rights Value	398
Total Fair Value Measurement Gain/(Loss)	1,928
Mortgage Banking [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Forward sales contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional or Principal Amount	306,062
Security Price Change	(4,731)
Total Fair Value Measurement Gain/(Loss)	(4,731)
Mortgage Banking [Member] | Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgages held for sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional or Principal Amount	127,176
Assumed Gain (Loss) From Loan Sale	(823)
Interest Rate Movement Effect	1,871
Servicing Rights Value	228
Total Fair Value Measurement Gain/(Loss)	$ 1,276