Borrowings - Schedule of Remaining Borrowing Capacity with FHLB (Parenthetical) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Jun. 21, 2016	Dec. 31, 2015	Dec. 31, 2014	Aug. 31, 2010	Oct. 31, 2009	Jun. 30, 2009	Aug. 31, 2008	Feb. 28, 2008
Interest Rate 0.74% and 0.43% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	0.74%		0.43%
Interest Rate 0.74% and 0.43% [Member] | Maximum [Member]
Borrowings Under Repurchase Agreements [Line items]
Borrowings	$ 150,000,000
Interest Rate 4.60% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings		4.60%	4.60%	0.27%			4.60%
FHLB advances, floating rate description	3 month LIBOR + 0.16%
FHLB advances, basis spread on floating rate	0.16%
Interest Rate 4.02% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings		4.02%	4.02%						4.02%
FHLB advances, floating rate description	3 month LIBOR + 0.11%
FHLB advances, basis spread on floating rate	0.11%
Interest Rate 4.10% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings		4.10%	4.10%					4.10%
FHLB advances, floating rate description	3 month LIBOR + 0.11%.
FHLB advances, basis spread on floating rate	0.11%
Interest Rate 4.47% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings		4.47%	4.47%		4.47%
FHLB advances, floating rate description	3 month LIBOR + 0.11%
FHLB advances, basis spread on floating rate	0.11%
Interest Rate 0.83% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	0.83%
Interest Rate 3.97% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	3.97%	3.97%				3.97%
FHLB advances, floating rate description	3 month LIBOR + 0.10
FHLB advances, basis spread on floating rate	0.10%
Interest Rate 1.25% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	1.25%
Interest Rate 1.05% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	1.05%
Interest Rate 1.17% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	1.17%
Interest Rate 1.35% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	1.35%
Interest Rate 1.27% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	1.27%
Interest Rate 1.47% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	1.47%
Interest Rate 4.72% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	4.72%
Interest Rate 4.31% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	4.31%
Interest Rate 3.05% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	3.05%
Interest Rate 5.24% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	5.24%
Interest Rate 3.35% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	3.35%
Interest Rate 4.00% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	4.00%
Interest Rate 2.96% [Member]
Borrowings Under Repurchase Agreements [Line items]
Fixed rate on borrowings	2.96%