Loans Receivable and Allowance for Loan Losses - Summary of Recorded Investment Net Charge-Offs, Unpaid Principal Balance and Related Allowance for Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Recorded Investment Net of Charge offs
Recorded Investment Net of Charge Offs, Total	$ 37,629		$ 37,629		$ 38,435
Unpaid Principal Balance
Unpaid Principal Balance, Total	38,905		38,905		39,089
Related Allowance	1,381		1,381		1,451
Average Recorded Investment
Average Recorded Investment, Total	36,045	$ 35,422	36,841	$ 33,419
Interest Income Recognized
Interest Income Recognized, Total	222	249	380	511
Multi-family
Recorded Investment Net of Charge offs
Recorded Investment Net of Charge Offs, With no related allowance recorded	1,343		1,343
Unpaid Principal Balance
Unpaid Principal Balance, With no related allowance recorded	1,343		1,343
Average Recorded Investment
Average Recorded Investment, With no related allowance recorded	672		448
Interest Income Recognized
Interest Income Recognized, With no related allowance recorded	8		8
Commercial and industrial
Recorded Investment Net of Charge offs
Recorded Investment Net of Charge Offs, With no related allowance recorded	5,642		5,642		9,138
Recorded Investment Net of Charge Offs, With an allowance recorded	8,108		8,108		8,323
Unpaid Principal Balance
Unpaid Principal Balance, With no related allowance recorded	5,889		5,889		9,287
Unpaid Principal Balance, With an allowance recorded	8,292		8,292		8,506
Related Allowance	1,062		1,062		650
Average Recorded Investment
Average Recorded Investment, With no related allowance recorded	5,736	6,678	6,870	5,251
Average Recorded Investment, With an allowance recorded	8,283	7,209	8,296	6,846
Interest Income Recognized
Interest Income Recognized, With no related allowance recorded	2	46	2	96
Interest Income Recognized, With an allowance recorded	11	0	12	22
Commercial real estate - owner occupied
Recorded Investment Net of Charge offs
Recorded Investment Net of Charge Offs, With no related allowance recorded	718		718		806
Recorded Investment Net of Charge Offs, With an allowance recorded	41		41		642
Unpaid Principal Balance
Unpaid Principal Balance, With no related allowance recorded	1,201		1,201		806
Unpaid Principal Balance, With an allowance recorded	41		41		642
Related Allowance	1		1		642
Average Recorded Investment
Average Recorded Investment, With no related allowance recorded	664	1,739	713	1,563
Average Recorded Investment, With an allowance recorded	455	839	517	839
Interest Income Recognized
Interest Income Recognized, With no related allowance recorded	0	0	0	3
Interest Income Recognized, With an allowance recorded	1	1	2	2
Commercial real estate - non-owner occupied
Recorded Investment Net of Charge offs
Recorded Investment Net of Charge Offs, With no related allowance recorded	2,536		2,536		160
Recorded Investment Net of Charge Offs, With an allowance recorded					0
Unpaid Principal Balance
Unpaid Principal Balance, With no related allowance recorded	2,648		2,648		272
Unpaid Principal Balance, With an allowance recorded					0
Related Allowance					0
Average Recorded Investment
Average Recorded Investment, With no related allowance recorded	1,390	884	980	1,257
Average Recorded Investment, With an allowance recorded		114		126
Interest Income Recognized
Interest Income Recognized, With no related allowance recorded	8	0	8	2
Interest Income Recognized, With an allowance recorded		0		0
Other
Recorded Investment Net of Charge offs
Recorded Investment Net of Charge Offs, With no related allowance recorded	94		94		30
Unpaid Principal Balance
Unpaid Principal Balance, With no related allowance recorded	94		94		30
Average Recorded Investment
Average Recorded Investment, With no related allowance recorded	96	56	74	56
Interest Income Recognized
Interest Income Recognized, With no related allowance recorded	0	0	0	0
Residential real estate
Recorded Investment Net of Charge offs
Recorded Investment Net of Charge Offs, With no related allowance recorded	4,301		4,301		3,628
Recorded Investment Net of Charge Offs, With an allowance recorded	4,474		4,474		5,619
Unpaid Principal Balance
Unpaid Principal Balance, With no related allowance recorded	4,546		4,546		3,801
Unpaid Principal Balance, With an allowance recorded	4,479		4,479		5,656
Related Allowance	313		313		155
Average Recorded Investment
Average Recorded Investment, With no related allowance recorded	3,959	2,660	3,849	4,001
Average Recorded Investment, With an allowance recorded	4,550	4,953	4,906	3,399
Interest Income Recognized
Interest Income Recognized, With no related allowance recorded	2	0	2	1
Interest Income Recognized, With an allowance recorded	38	45	63	84
Manufactured housing
Recorded Investment Net of Charge offs
Recorded Investment Net of Charge Offs, With no related allowance recorded	10,144		10,144		9,865
Recorded Investment Net of Charge Offs, With an allowance recorded	228		228		224
Unpaid Principal Balance
Unpaid Principal Balance, With no related allowance recorded	10,144		10,144		9,865
Unpaid Principal Balance, With an allowance recorded	228		228		224
Related Allowance	5		5		$ 4
Average Recorded Investment
Average Recorded Investment, With no related allowance recorded	10,015	10,074	9,963	9,937
Average Recorded Investment, With an allowance recorded	225	216	225	144
Interest Income Recognized
Interest Income Recognized, With no related allowance recorded	146	152	277	293
Interest Income Recognized, With an allowance recorded	$ 6	$ 5	$ 6	$ 8