Assets Acquired in FDIC-Assisted Acquisitions - Loans Receivable at Acquisition Date for Loans with Deterioration in Credit Quality (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2012
Schedule of Covered Loans with Deterioration of Credit Quality [Line Items]
Contractually required principal payments receivable		$ 137,407
Non-accretable difference		53,603
Present value of cash flows expected to be collected		83,804
Accretable difference		10,390
Fair value of loans acquired with deterioration of credit quality	67,165	73,414
Central Bank of Georgia (CBG) [Member]
Schedule of Covered Loans with Deterioration of Credit Quality [Line Items]
Contractually required principal payments receivable		137,407
Non-accretable difference		53,603
Present value of cash flows expected to be collected		83,804
Accretable difference		10,390
Fair value of loans acquired with deterioration of credit quality		$ 73,414