Loans - Presentation of Loans Individually Evaluated for Impairment by Class (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	$ 20,623	$ 24,562	$ 22,728
With no specific allowance recorded, Recorded Investment	8,587	12,313	10,444
With no specific allowance recorded, Average Recorded Investment	9,518	12,328
With no specific allowance recorded, Interest Income Recognized	117	25
With no specific allowance recorded, Cash Basis Income Recognized	108	18
With a specific allowance recorded, Unpaid Principal Balance	19,499	32,816	24,114
With a specific allowance recorded, Recorded Investment	19,252	30,298	21,104
With a specific allowance recorded, Allowance for Loan Losses Allocated	1,732	3,022	3,016
With a specific allowance recorded, Average Recorded Investment	20,180	28,809
With a specific allowance recorded, Interest Income Recognized	301	417
With a specific allowance recorded, Cash Basis Income Recognized	241	342
Total Unpaid Principal Balance	40,122	57,378	46,842
Total Recorded Investment	27,839	42,611	31,548
Total Average Recorded Investment	29,698	41,137
Total Interest Income Recognized	418	442
Total Cash Basis Income Recognized	349	360
Commercial Loans [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	9,578	13,638	10,804
With no specific allowance recorded, Recorded Investment	783	4,296	1,713
With no specific allowance recorded, Average Recorded Investment	1,250	4,343
With no specific allowance recorded, Interest Income Recognized	48	1
With no specific allowance recorded, Cash Basis Income Recognized	48	1
With a specific allowance recorded, Unpaid Principal Balance	1,946	12,402	7,167
With a specific allowance recorded, Recorded Investment	1,902	9,884	4,305
With a specific allowance recorded, Allowance for Loan Losses Allocated	19	1,029	1,271
With a specific allowance recorded, Average Recorded Investment	3,104	7,596
With a specific allowance recorded, Interest Income Recognized	35	109
With a specific allowance recorded, Cash Basis Income Recognized	33	107
Commercial Loans [Member] | Multifamily [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	476	97	55
With no specific allowance recorded, Recorded Investment	419
With no specific allowance recorded, Average Recorded Investment	210
With no specific allowance recorded, Interest Income Recognized	9
With no specific allowance recorded, Cash Basis Income Recognized	9
Commercial Loans [Member] | Nonresidential [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	738	1,042	2,278
With no specific allowance recorded, Recorded Investment	166	212	1,489
With no specific allowance recorded, Average Recorded Investment	828	259
With no specific allowance recorded, Interest Income Recognized	22	1
With no specific allowance recorded, Cash Basis Income Recognized	22	1
With a specific allowance recorded, Unpaid Principal Balance	1,946	11,348	6,930
With a specific allowance recorded, Recorded Investment	1,902	8,924	4,133
With a specific allowance recorded, Allowance for Loan Losses Allocated	19	936	1,193
With a specific allowance recorded, Average Recorded Investment	3,018	6,954
With a specific allowance recorded, Interest Income Recognized	35	109
With a specific allowance recorded, Cash Basis Income Recognized	33	107
Commercial Loans [Member] | Land [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	3,922	3,922	3,922
With no specific allowance recorded, Recorded Investment	9	384	34
With no specific allowance recorded, Average Recorded Investment	22	384
Commercial Loans [Member] | Construction [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	3,593	3,593	3,594
Commercial Loans [Member] | Secured [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	242	3,860	242
With no specific allowance recorded, Recorded Investment	189	3,700	190
With no specific allowance recorded, Average Recorded Investment	190	3,700
With a specific allowance recorded, Unpaid Principal Balance		1,054	237
With a specific allowance recorded, Recorded Investment		960	172
With a specific allowance recorded, Allowance for Loan Losses Allocated		93	78
With a specific allowance recorded, Average Recorded Investment	86	642
Commercial Loans [Member] | Unsecured [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	607	1,124	713
With no specific allowance recorded, Interest Income Recognized	17
With no specific allowance recorded, Cash Basis Income Recognized	17
Residential Mortgage Loans [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	7,584	7,875	8,736
With no specific allowance recorded, Recorded Investment	5,764	6,081	6,758
With no specific allowance recorded, Average Recorded Investment	6,261	5,974
With no specific allowance recorded, Interest Income Recognized	53	20
With no specific allowance recorded, Cash Basis Income Recognized	46	14
With a specific allowance recorded, Unpaid Principal Balance	11,252	12,710	10,810
With a specific allowance recorded, Recorded Investment	11,138	12,710	10,727
With a specific allowance recorded, Allowance for Loan Losses Allocated	1,231	1,407	1,245
With a specific allowance recorded, Average Recorded Investment	10,933	13,096
With a specific allowance recorded, Interest Income Recognized	162	189
With a specific allowance recorded, Cash Basis Income Recognized	122	136
Residential Mortgage Loans [Member] | One-to Four-Family [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	7,584	7,875	8,736
With no specific allowance recorded, Recorded Investment	5,764	6,081	6,758
With no specific allowance recorded, Average Recorded Investment	6,261	5,974
With no specific allowance recorded, Interest Income Recognized	53	20
With no specific allowance recorded, Cash Basis Income Recognized	46	14
With a specific allowance recorded, Unpaid Principal Balance	11,252	12,710	10,810
With a specific allowance recorded, Recorded Investment	11,138	12,710	10,727
With a specific allowance recorded, Allowance for Loan Losses Allocated	1,231	1,407	1,245
With a specific allowance recorded, Average Recorded Investment	10,933	13,096
With a specific allowance recorded, Interest Income Recognized	162	189
With a specific allowance recorded, Cash Basis Income Recognized	122	136
Consumer Loans [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	3,461	3,049	3,188
With no specific allowance recorded, Recorded Investment	2,040	1,936	1,973
With no specific allowance recorded, Average Recorded Investment	2,007	2,011
With no specific allowance recorded, Interest Income Recognized	16	4
With no specific allowance recorded, Cash Basis Income Recognized	14	3
With a specific allowance recorded, Unpaid Principal Balance	6,301	7,704	6,137
With a specific allowance recorded, Recorded Investment	6,212	7,704	6,072
With a specific allowance recorded, Allowance for Loan Losses Allocated	482	586	500
With a specific allowance recorded, Average Recorded Investment	6,143	8,117
With a specific allowance recorded, Interest Income Recognized	104	119
With a specific allowance recorded, Cash Basis Income Recognized	86	99
Consumer Loans [Member] | Home Equity [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	2,179	1,951	2,159
With no specific allowance recorded, Recorded Investment	1,612	1,332	1,583
With no specific allowance recorded, Average Recorded Investment	1,598	1,525
With no specific allowance recorded, Interest Income Recognized	12	3
With no specific allowance recorded, Cash Basis Income Recognized	11	2
With a specific allowance recorded, Unpaid Principal Balance	5,461	6,857	5,390
With a specific allowance recorded, Recorded Investment	5,382	6,857	5,335
With a specific allowance recorded, Allowance for Loan Losses Allocated	409	497	426
With a specific allowance recorded, Average Recorded Investment	5,359	7,047
With a specific allowance recorded, Interest Income Recognized	92	110
With a specific allowance recorded, Cash Basis Income Recognized	76	90
Consumer Loans [Member] | Auto [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	24	15	11
With no specific allowance recorded, Recorded Investment	13	9	3
With no specific allowance recorded, Average Recorded Investment	8	12
Consumer Loans [Member] | Marine [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	584	546	585
With no specific allowance recorded, Recorded Investment	195	303	267
With no specific allowance recorded, Average Recorded Investment	231	287
With no specific allowance recorded, Interest Income Recognized	1
With no specific allowance recorded, Cash Basis Income Recognized	1
With a specific allowance recorded, Unpaid Principal Balance	106	159	108
With a specific allowance recorded, Recorded Investment	106	159	108
With a specific allowance recorded, Allowance for Loan Losses Allocated	1	3	1
With a specific allowance recorded, Average Recorded Investment	107	161
With a specific allowance recorded, Interest Income Recognized	2	2
With a specific allowance recorded, Cash Basis Income Recognized	1	2
Consumer Loans [Member] | Recreational Vehicle [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance	674	534	433
With no specific allowance recorded, Recorded Investment	220	289	120
With no specific allowance recorded, Average Recorded Investment	170	184
With no specific allowance recorded, Interest Income Recognized	3	1
With no specific allowance recorded, Cash Basis Income Recognized	2	1
With a specific allowance recorded, Unpaid Principal Balance	734	688	639
With a specific allowance recorded, Recorded Investment	724	688	629
With a specific allowance recorded, Allowance for Loan Losses Allocated	72	86	$ 73
With a specific allowance recorded, Average Recorded Investment	677	905
With a specific allowance recorded, Interest Income Recognized	10	7
With a specific allowance recorded, Cash Basis Income Recognized	$ 9	7
Consumer Loans [Member] | Other [Member]
Financing Receivable Impaired [Line Items]
With no specific allowance recorded, Unpaid Principal Balance		3
With no specific allowance recorded, Recorded Investment		3
With no specific allowance recorded, Average Recorded Investment		3
With a specific allowance recorded, Average Recorded Investment		$ 4