Securities - Fair Value of Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Dec. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	$ 504,855	$ 445,839
Gross Unrealized Gains	3,883	922
Gross Unrealized Losses	(3,687)	(6,929)
Available for sale Securities, Fair Value	505,051	439,831
Held to maturity, Amortized Cost	199,474	193,194
Held to maturity, Gross Unrealized Gains	5,086	3,628
Held to maturity, Gross Unrealized Losses	(1,018)	(2,736)
Held to maturity, Fair Value	203,542	194,086	$ 194,086
State and Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	136,539	117,327
Gross Unrealized Gains	2,454	324
Gross Unrealized Losses	(507)	(1,059)
Available for sale Securities, Fair Value	138,486	116,592
Held to maturity, Amortized Cost	177,781	165,607
Held to maturity, Gross Unrealized Gains	4,683	2,700
Held to maturity, Gross Unrealized Losses	(930)	(2,485)
Held to maturity, Fair Value	181,534	165,822
Federal Agency Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	133,038	139,040
Gross Unrealized Gains	213	254
Gross Unrealized Losses	(1,337)	(2,099)
Available for sale Securities, Fair Value	131,914	137,195
Held to maturity, Amortized Cost	6,102	6,530
Held to maturity, Gross Unrealized Gains	39	31
Held to maturity, Gross Unrealized Losses	(27)	(71)
Held to maturity, Fair Value	6,114	6,490
Federal Agency Mortgage-backed Pools [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	212,154	180,183
Gross Unrealized Gains	509	251
Gross Unrealized Losses	(1,782)	(3,707)
Available for sale Securities, Fair Value	210,881	176,726
Held to maturity, Amortized Cost	15,591	21,057
Held to maturity, Gross Unrealized Gains	364	897
Held to maturity, Gross Unrealized Losses	(61)	(180)
Held to maturity, Fair Value	15,894	21,774
U.S. Treasury and Federal Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	20,020	8,051
Gross Unrealized Gains	4	2
Gross Unrealized Losses	(58)	(64)
Available for sale Securities, Fair Value	19,966	7,989
Private Labeled Mortgage-backed Pools [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	1,871
Gross Unrealized Losses	(3)
Available for sale Securities, Fair Value	1,868
Corporate Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available for sale investment securities, Amortized Cost	1,233	1,238
Gross Unrealized Gains	703	91
Available for sale Securities, Fair Value	$ 1,936	$ 1,329

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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