Loans and Allowance for Credit Losses - Schedule of Accretable Difference on Purchased Loans (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning, Balance	$ 31,579
New loans purchased
Accretion of income	(8,946)
Reclassifications from (to) nonaccretable difference	3,253
Disposals/other adjustments	(467)
Ending, Balance	25,419
Monroe Bancorp [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning, Balance	11,834
New loans purchased
Accretion of income	(2,634)
Reclassifications from (to) nonaccretable difference	(258)
Disposals/other adjustments	(305)
Ending, Balance	8,637
Integra Noncovered [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning, Balance	3,575
New loans purchased
Accretion of income	(729)
Reclassifications from (to) nonaccretable difference	(12)
Disposals/other adjustments	(49)
Ending, Balance	2,785
IBT [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning, Balance	16,170
New loans purchased
Accretion of income	(5,583)
Reclassifications from (to) nonaccretable difference	3,523
Disposals/other adjustments	(113)
Ending, Balance	$ 13,997