Investment Securities - Summary of Gross Unrealized Losses and Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	$ 53,468	$ 57,577
Unrealized Losses, Less Than 12 Months	1,082	1,101
Fair Value, 12 Months or More	3,851	1,635
Unrealized Losses, 12 Months or More	87	14
Total Fair Value	57,319	59,212
Total Unrealized Losses	1,169	1,115
US government agencies
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	6,503	6,508
Unrealized Losses, Less Than 12 Months	33	32
Fair Value, 12 Months or More	0	0
Unrealized Losses, 12 Months or More	0	0
Total Fair Value	6,503	6,508
Total Unrealized Losses	33	32
Residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	44,986	49,109
Unrealized Losses, Less Than 12 Months	997	1,017
Fair Value, 12 Months or More	3,851	1,635
Unrealized Losses, 12 Months or More	87	14
Total Fair Value	48,837	50,744
Total Unrealized Losses	1,084	1,031
Mutual fund
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less Than 12 Months	1,979	1,960
Unrealized Losses, Less Than 12 Months	52	52
Fair Value, 12 Months or More	0	0
Unrealized Losses, 12 Months or More	0	0
Total Fair Value	1,979	1,960
Total Unrealized Losses	$ 52	$ 52