Assets and Liabilities of SCB Recorded at Provisional Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Feb. 10, 2012 SCB Bank [Member]	Feb. 10, 2012 SCB Bank [Member] Commercial	Feb. 10, 2012 SCB Bank [Member] Residential Mortgage	Feb. 10, 2012 SCB Bank [Member] Installment Loans	Feb. 10, 2012 SCB Bank [Member] Non Interest Bearing Deposits	Feb. 10, 2012 SCB Bank [Member] Negotiable Order of Withdrawal Accounts	Feb. 10, 2012 SCB Bank [Member] Money Market Funds	Feb. 10, 2012 SCB Bank [Member] Certificates of Deposit
Business Acquisition [Line Items]
Cash and due from banks			$ 29,113
Investment securities, available for sale			18,896
Federal Home Loan Bank stock			1,761
Loans			93,793	51,042	11,181	31,570
Premises			1,516
Core deposit intangible			484
Other assets			560
Total Assets Purchased			146,123
Deposits			125,909				13,715	14,746	25,843	71,605
Federal Home Loan Bank advances			10,286
Other liabilities			804
Total Liabilities Assumed			136,999
Net Gain on Acquisition		$ 9,124	$ 9,124