Segment Information - Summary of Segment Information (Parenthetical) (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Taxable-equivalent adjustment	$ 6,332,000	$ 5,838,000
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Average assets		315,000,000
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Average assets		$ 315,000,000