Segment Information - Summary of Segment Information (Parenthetical) (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Taxable-equivalent adjustment	$ 6,522,000	$ 6,020,000	$ 12,854,000	$ 11,858,000
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Average assets				323,000,000
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Average assets				$ 323,000,000