FDIC Indemnification Asset (Detail) (USD $)	3 Months Ended	9 Months Ended
	Jun. 30, 2012	Sep. 30, 2012
FDIC Cash Payments Received Total		$ 13,300,000
FDIC Loss On Loans To FDIC Indemnification Asset		11,700,000
FDIC Claim		28,300,000
Increase in net interest income	472,000
Assumption Of Loss [Member] | Cape Fear [Member]
FDIC Indemnification Asset Losses		32,400,000
Cape Fear [Member]
FDIC Indemnification Asset Losses		110,000,000
FDIC Indemnification Asset Reimbursement Rate		80.00%
FDIC reimbursements Amount		32,400,000
FDIC Indemnification Asset Reimbursement Rate1		95.00%
Plantation [Member]
FDIC Indemnification Asset Losses		55,000,000
FDIC Indemnification Asset Reimbursement Rate		80.00%
FDIC reimbursements Amount		$ 65,000,000
FDIC Indemnification Asset Reimbursement Rate1		60.00%