Accrued Interest Receivable and Other Assets - Details of Accrued Interest Receivable and Other Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Interest Receivable and Other Assets [Abstract]
Other real estate owned	$ 1,843	$ 4,969
Accrued interest receivable	12,362	10,794
Accrued income and other receivables	3,872	7,751
Fair market value of derivative financial instruments	601	1,058
Other prepaid expenses	21,496	17,686
Net federal deferred tax assets	1,174	9,965
Other Assets	154	20
Total accrued interest and other assets	$ 41,502	$ 52,243