Loans - Presentation of Age Analysis of Past-Due Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	$ 21,809	$ 22,617
Current Loans	1,467,993	1,309,976
Total loans	1,489,802	1,332,593
30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	4,913	5,383
60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,546	955
Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	15,350	16,279
Commercial Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	7,818	8,446
Current Loans	486,365	361,306
Total loans	494,183	369,752
Commercial Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	27	488
Commercial Loans [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	7,791	7,958
Commercial Loans [Member] | Multifamily [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current Loans	107,066	80,170
Total loans	107,066	80,170
Commercial Loans [Member] | Nonresidential [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	3,442	3,558
Current Loans	222,257	171,898
Total loans	225,699	175,456
Commercial Loans [Member] | Nonresidential [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	27
Commercial Loans [Member] | Nonresidential [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	3,415	3,558
Commercial Loans [Member] | Land [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	134	384
Current Loans	9,267	8,917
Total loans	9,401	9,301
Commercial Loans [Member] | Land [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	134	384
Commercial Loans [Member] | Construction [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current Loans	45,137	38,812
Total loans	45,137	38,812
Commercial Loans [Member] | Secured [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	4,242	4,504
Current Loans	92,089	58,678
Total loans	96,331	63,182
Commercial Loans [Member] | Secured [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		488
Commercial Loans [Member] | Secured [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	4,242	4,016
Commercial Loans [Member] | Unsecured [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current Loans	10,549	2,831
Total loans	10,549	2,831
Residential Mortgage Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	10,373	10,379
Current Loans	781,395	764,204
Total loans	791,768	774,583
Residential Mortgage Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	3,669	3,843
Residential Mortgage Loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,195	635
Residential Mortgage Loans [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	5,509	5,901
Residential Mortgage Loans [Member] | Construction [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Current Loans	35,875	40,898
Total loans	35,875	40,898
Residential Mortgage Loans [Member] | One-to Four-Family [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	10,373	10,379
Current Loans	745,520	723,306
Total loans	755,893	733,685
Residential Mortgage Loans [Member] | One-to Four-Family [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	3,669	3,843
Residential Mortgage Loans [Member] | One-to Four-Family [Member] | 60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,195	635
Residential Mortgage Loans [Member] | One-to Four-Family [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	5,509	5,901
Consumer Loans [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	3,618	3,792
Current Loans	200,233	184,466
Total loans	203,851	188,258
Consumer Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,217	1,052
Consumer Loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	351	320
Consumer Loans [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,050	2,420
Consumer Loans [Member] | Home Equity [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,739	3,017
Current Loans	160,240	158,321
Total loans	162,979	161,338
Consumer Loans [Member] | Home Equity [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	926	961
Consumer Loans [Member] | Home Equity [Member] | 60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	261	268
Consumer Loans [Member] | Home Equity [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,552	1,788
Consumer Loans [Member] | Automobile [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	12	15
Current Loans	28,257	11,333
Total loans	28,269	11,348
Consumer Loans [Member] | Automobile [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		5
Consumer Loans [Member] | Automobile [Member] | 60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	7
Consumer Loans [Member] | Automobile [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	5	10
Consumer Loans [Member] | Marine [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	287	168
Current Loans	1,572	2,531
Total loans	1,859	2,699
Consumer Loans [Member] | Marine [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	43
Consumer Loans [Member] | Marine [Member] | 60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		51
Consumer Loans [Member] | Marine [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	244	117
Consumer Loans [Member] | Recreational Vehicle [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	574	565
Current Loans	7,625	10,091
Total loans	8,199	10,656
Consumer Loans [Member] | Recreational Vehicle [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	246	71
Consumer Loans [Member] | Recreational Vehicle [Member] | 60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	82
Consumer Loans [Member] | Recreational Vehicle [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	246	494
Consumer Loans [Member] | Other [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	6	27
Current Loans	2,539	2,190
Total loans	2,545	2,217
Consumer Loans [Member] | Other [Member] | 30-59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2	15
Consumer Loans [Member] | Other [Member] | 60-89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1	1
Consumer Loans [Member] | Other [Member] | Greater than 90 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	$ 3	$ 11