Commitments and Contingencies - Schedule of Commitments (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total unfunded off-balance sheet credit risk	$ 955,476	$ 739,472
Commitments to extend credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total unfunded off-balance sheet credit risk	953,576	737,572
Plexus Capital - Fund II Investment Commitment | Short-term Debt
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total unfunded off-balance sheet credit risk	100	100
Plexus Capital - Fund III Investment Commitment | Short-term Debt
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total unfunded off-balance sheet credit risk	300	300
Five Points Mezzanine Fund III Commitment | Short-term Debt
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Total unfunded off-balance sheet credit risk	$ 1,500	$ 1,500