Loans - Presentation of Loans Individually Evaluated for Impairment by Class (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	$ 24,898	$ 23,081	$ 24,898	$ 23,081	$ 24,403
With no specific allowance recorded, Recorded Investment	12,859	12,886	12,859	12,886	12,340
With no specific allowance recorded, Average Recorded Investment	12,588	13,284	12,503	15,043
With no specific allowance recorded, Interest Income Recognized	20	20	61	49
With no specific allowance recorded, Cash Basis Income Recognized	20	19	51	45
With a specific allowance recorded, Unpaid Principal Balance	31,142	33,704	31,142	33,704	27,499
With a specific allowance recorded, Recorded Investment	28,765	30,968	28,765	30,968	27,319
With a specific allowance recorded, Allowance for Loan Losses Allocated	2,884	3,085	2,884	3,085	2,816
With a specific allowance recorded, Average Recorded Investment	29,534	31,549	28,795	30,668
With a specific allowance recorded, Interest Income Recognized	233	221	628	652
With a specific allowance recorded, Cash Basis Income Recognized	229	217	558	573
Total Unpaid Principal Balance	56,040	56,785	56,040	56,785	51,902
Total Recorded Investment	41,624	43,854	41,624	43,854	39,659
Total Average Recorded Investment	42,122	44,833	41,298	45,711
Total Interest Income Recognized	253	241	689	701
Total Cash Basis Income Recognized	249	236	609	618
Commercial Loans [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	13,856	14,581	13,856	14,581	13,911
With no specific allowance recorded, Recorded Investment	4,410	6,715	4,410	6,715	4,390
With no specific allowance recorded, Average Recorded Investment	4,353	6,836	4,365	8,132
With no specific allowance recorded, Interest Income Recognized	1	6	3	7
With no specific allowance recorded, Cash Basis Income Recognized	1	5	3	6
With a specific allowance recorded, Unpaid Principal Balance	11,881	9,613	11,881	9,613	5,488
With a specific allowance recorded, Recorded Investment	9,504	6,877	9,504	6,877	5,308
With a specific allowance recorded, Allowance for Loan Losses Allocated	1,015	673	1,015	673	568
With a specific allowance recorded, Average Recorded Investment	9,695	7,216	8,232	6,155
With a specific allowance recorded, Interest Income Recognized	15	38	124	76
With a specific allowance recorded, Cash Basis Income Recognized	15	34	122	72
Commercial Loans [Member] | Multifamily [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	95	109	95	109	165
With no specific allowance recorded, Average Recorded Investment		43		64
With no specific allowance recorded, Interest Income Recognized		3		3
With no specific allowance recorded, Cash Basis Income Recognized		3		3
With a specific allowance recorded, Unpaid Principal Balance		153		153
With a specific allowance recorded, Recorded Investment		85		85
With a specific allowance recorded, Allowance for Loan Losses Allocated		17		17
With a specific allowance recorded, Average Recorded Investment		43		31
Commercial Loans [Member] | Nonresidential [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	1,382	4,175	1,382	4,175	1,215
With no specific allowance recorded, Recorded Investment	326	2,431	326	2,431	306
With no specific allowance recorded, Average Recorded Investment	269	2,441	281	3,567
With no specific allowance recorded, Interest Income Recognized	1	2	3	3
With no specific allowance recorded, Cash Basis Income Recognized	1	2	3	3
With a specific allowance recorded, Unpaid Principal Balance	10,854	6,321	10,854	6,321	5,164
With a specific allowance recorded, Recorded Investment	8,571	6,141	8,571	6,141	4,984
With a specific allowance recorded, Allowance for Loan Losses Allocated	922	611	922	611	565
With a specific allowance recorded, Average Recorded Investment	8,748	6,254	7,493	4,833
With a specific allowance recorded, Interest Income Recognized	15	38	124	76
With a specific allowance recorded, Cash Basis Income Recognized	15	34	122	72
Commercial Loans [Member] | Land [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	3,922	3,922	3,922	3,922	3,922
With no specific allowance recorded, Recorded Investment	384	496	384	496	384
With no specific allowance recorded, Average Recorded Investment	384	514	384	523
Commercial Loans [Member] | Construction [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	3,594	1,126	3,594	1,126	3,593
With no specific allowance recorded, Recorded Investment		88		88
With no specific allowance recorded, Average Recorded Investment		138		276
With a specific allowance recorded, Unpaid Principal Balance		2,815		2,815
With a specific allowance recorded, Recorded Investment		327		327
With a specific allowance recorded, Allowance for Loan Losses Allocated		42		42
With a specific allowance recorded, Average Recorded Investment		595		967
Commercial Loans [Member] | Secured [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	3,745	3,892	3,745	3,892	3,884
With no specific allowance recorded, Recorded Investment	3,700	3,700	3,700	3,700	3,700
With no specific allowance recorded, Average Recorded Investment	3,700	3,700	3,700	3,702
With a specific allowance recorded, Unpaid Principal Balance	1,027	324	1,027	324	324
With a specific allowance recorded, Recorded Investment	933	324	933	324	324
With a specific allowance recorded, Allowance for Loan Losses Allocated	93	3	93	3	3
With a specific allowance recorded, Average Recorded Investment	947	324	739	324
Commercial Loans [Member] | Unsecured [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	1,118	1,357	1,118	1,357	1,132
With no specific allowance recorded, Interest Income Recognized		1		1
Residential Mortgage Loans [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	8,102	5,925	8,102	5,925	7,607
With no specific allowance recorded, Recorded Investment	6,522	4,411	6,522	4,411	5,866
With no specific allowance recorded, Average Recorded Investment	6,302	4,530	6,156	4,939
With no specific allowance recorded, Interest Income Recognized	17	12	52	30
With no specific allowance recorded, Cash Basis Income Recognized	17	12	42	27
With a specific allowance recorded, Unpaid Principal Balance	12,033	14,828	12,033	14,828	13,482
With a specific allowance recorded, Recorded Investment	12,033	14,828	12,033	14,828	13,482
With a specific allowance recorded, Allowance for Loan Losses Allocated	1,333	1,651	1,333	1,651	1,541
With a specific allowance recorded, Average Recorded Investment	12,372	14,712	12,742	14,524
With a specific allowance recorded, Interest Income Recognized	124	104	297	331
With a specific allowance recorded, Cash Basis Income Recognized	122	104	251	280
Residential Mortgage Loans [Member] | One-to Four-Family [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	8,102	5,925	8,102	5,925	7,607
With no specific allowance recorded, Recorded Investment	6,522	4,411	6,522	4,411	5,866
With no specific allowance recorded, Average Recorded Investment	6,302	4,530	6,156	4,939
With no specific allowance recorded, Interest Income Recognized	17	12	52	30
With no specific allowance recorded, Cash Basis Income Recognized	17	12	42	27
With a specific allowance recorded, Unpaid Principal Balance	12,033	14,828	12,033	14,828	13,482
With a specific allowance recorded, Recorded Investment	12,033	14,828	12,033	14,828	13,482
With a specific allowance recorded, Allowance for Loan Losses Allocated	1,333	1,651	1,333	1,651	1,541
With a specific allowance recorded, Average Recorded Investment	12,372	14,712	12,742	14,524
With a specific allowance recorded, Interest Income Recognized	124	104	297	331
With a specific allowance recorded, Cash Basis Income Recognized	122	104	251	280
Consumer Loans [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	2,940	2,575	2,940	2,575	2,885
With no specific allowance recorded, Recorded Investment	1,927	1,760	1,927	1,760	2,084
With no specific allowance recorded, Average Recorded Investment	1,933	1,918	1,982	1,972
With no specific allowance recorded, Interest Income Recognized	2	2	6	12
With no specific allowance recorded, Cash Basis Income Recognized	2	2	6	12
With a specific allowance recorded, Unpaid Principal Balance	7,228	9,263	7,228	9,263	8,529
With a specific allowance recorded, Recorded Investment	7,228	9,263	7,228	9,263	8,529
With a specific allowance recorded, Allowance for Loan Losses Allocated	536	761	536	761	707
With a specific allowance recorded, Average Recorded Investment	7,467	9,621	7,821	9,989
With a specific allowance recorded, Interest Income Recognized	94	79	207	245
With a specific allowance recorded, Cash Basis Income Recognized	92	79	185	221
Consumer Loans [Member] | Home Equity [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	1,858	1,940	1,858	1,940	2,245
With no specific allowance recorded, Recorded Investment	1,339	1,388	1,339	1,388	1,718
With no specific allowance recorded, Average Recorded Investment	1,336	1,534	1,463	1,586
With no specific allowance recorded, Interest Income Recognized	1	2	4	9
With no specific allowance recorded, Cash Basis Income Recognized	1	2	4	9
With a specific allowance recorded, Unpaid Principal Balance	6,279	8,554	6,279	8,554	7,236
With a specific allowance recorded, Recorded Investment	6,279	8,554	6,279	8,554	7,236
With a specific allowance recorded, Allowance for Loan Losses Allocated	447	646	447	646	522
With a specific allowance recorded, Average Recorded Investment	6,568	8,905	6,791	9,260
With a specific allowance recorded, Interest Income Recognized	84	79	188	234
With a specific allowance recorded, Cash Basis Income Recognized	82	79	167	211
Consumer Loans [Member] | Auto [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	16	30	16	30	20
With no specific allowance recorded, Recorded Investment	9	22	9	22	14
With no specific allowance recorded, Average Recorded Investment	9	27	11	47
With a specific allowance recorded, Unpaid Principal Balance		4		4
With a specific allowance recorded, Recorded Investment		4		4
With a specific allowance recorded, Average Recorded Investment		5		6
Consumer Loans [Member] | Marine [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	544	510	544	510	496
With no specific allowance recorded, Recorded Investment	302	284	302	284	271
With no specific allowance recorded, Average Recorded Investment	303	289	292	221
With no specific allowance recorded, Interest Income Recognized				2
With no specific allowance recorded, Cash Basis Income Recognized				2
With a specific allowance recorded, Unpaid Principal Balance	156		156		163
With a specific allowance recorded, Recorded Investment	156		156		163
With a specific allowance recorded, Allowance for Loan Losses Allocated	4		4		3
With a specific allowance recorded, Average Recorded Investment	158		159
With a specific allowance recorded, Interest Income Recognized	2		4
With a specific allowance recorded, Cash Basis Income Recognized	2		4
Consumer Loans [Member] | Recreational Vehicle [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	518	95	518	95	121
With no specific allowance recorded, Recorded Investment	273	66	273	66	78
With no specific allowance recorded, Average Recorded Investment	281	68	213	117
With no specific allowance recorded, Interest Income Recognized	1		2	1
With no specific allowance recorded, Cash Basis Income Recognized	1		2	1
With a specific allowance recorded, Unpaid Principal Balance	793	705	793	705	1,122
With a specific allowance recorded, Recorded Investment	793	705	793	705	1,122
With a specific allowance recorded, Allowance for Loan Losses Allocated	85	115	85	115	181
With a specific allowance recorded, Average Recorded Investment	741	$ 711	868	723
With a specific allowance recorded, Interest Income Recognized	8		15	11
With a specific allowance recorded, Cash Basis Income Recognized	8		14	10
Consumer Loans [Member] | Other [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	4		4		3
With no specific allowance recorded, Recorded Investment	4		4		3
With no specific allowance recorded, Average Recorded Investment	$ 4		3	$ 1
With a specific allowance recorded, Unpaid Principal Balance					8
With a specific allowance recorded, Recorded Investment					8
With a specific allowance recorded, Allowance for Loan Losses Allocated					$ 1
With a specific allowance recorded, Average Recorded Investment			$ 3