Segment Information - Summary of Segment Information (Parenthetical) (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting [Abstract]
Taxable-equivalent adjustment	$ 6,725,000	$ 6,248,000	$ 19,579,000	$ 18,106,000