Loans Receivable and Allowance for Loan Losses - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	$ 36,797	$ 36,047
Recorded Investment, With No Allocated Allowance	53,697	67,960
Allowance on Impaired Loans	(3,402)	(4,791)
Impaired Loans, net of allowance	87,092	99,216
Impaired Financing Receivable, Recorded Investment	90,494	104,007
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	44,509	39,560
Unpaid Contractual Principal Balance, With No Related Allowance	76,217	93,141
Impaired Financing Receivable, Unpaid Principal Balance	120,726	132,701
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	37,858	41,952	$ 45,077
Average Recorded Investment, With No Related Allowance	64,119	70,012	75,236
Average Recorded Investment, Total	101,977	111,964	120,313
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	1,100	996	1,162
Interest Income Recognized during Impairment, With No Related Allowance	962	1,931	2,279
Interest Income Recognized during Impairment, Total	2,062	2,927	3,441
Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	7,394	8,474
Recorded Investment, With No Allocated Allowance	24,533	19,605
Allowance on Impaired Loans	(991)	(391)
Impaired Financing Receivable, Recorded Investment	31,927	28,079
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	8,815	10,566
Unpaid Contractual Principal Balance, With No Related Allowance	35,073	26,593
Impaired Financing Receivable, Unpaid Principal Balance	43,888	37,159
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	6,195	10,299	2,790
Average Recorded Investment, With No Related Allowance	21,838	20,857	21,959
Average Recorded Investment, Total	28,033	31,156	24,749
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	290	396	70
Interest Income Recognized during Impairment, With No Related Allowance	432	591	921
Interest Income Recognized during Impairment, Total	722	987	991
WIthout charge-offs
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	33,344	35,365
Recorded Investment, With No Allocated Allowance	41,904	59,607
With charge-offs
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	3,453	681
Recorded Investment, With No Allocated Allowance	11,793	8,354
Real estate-Residential
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	0
Recorded Investment, With No Allocated Allowance	0	0
Allowance on Impaired Loans	0	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	0	0
Unpaid Contractual Principal Balance, With No Related Allowance	0	0
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	50	0
Average Recorded Investment, With No Related Allowance	0	0	1,105
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	0	0
Real estate-Residential | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	0
Recorded Investment, With No Allocated Allowance	0	0
Allowance on Impaired Loans	0	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	0	0
Unpaid Contractual Principal Balance, With No Related Allowance	0	0
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	50	0
Average Recorded Investment, With No Related Allowance	0	0	235
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	0	0
Real estate-Construction
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	0
Recorded Investment, With No Allocated Allowance	10,165	0
Allowance on Impaired Loans	0	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	0	0
Unpaid Contractual Principal Balance, With No Related Allowance	10,165	0
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	0	0
Average Recorded Investment, With No Related Allowance	2,033	520	1,611
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	0	0
Real estate-Construction | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	0
Recorded Investment, With No Allocated Allowance	10,165	0
Allowance on Impaired Loans	0	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	0	0
Unpaid Contractual Principal Balance, With No Related Allowance	10,165	0
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	0	0
Average Recorded Investment, With No Related Allowance	2,033	0	0
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	0	0
Commercial Business
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	19,254	22,203
Recorded Investment, With No Allocated Allowance	3,485	13,155
Allowance on Impaired Loans	(3,073)	(4,351)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	20,849	23,928
Unpaid Contractual Principal Balance, With No Related Allowance	8,628	17,850
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	21,814	23,146	23,695
Average Recorded Investment, With No Related Allowance	8,545	18,041	16,312
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	601	511	631
Interest Income Recognized during Impairment, With No Related Allowance	126	531	697
Commercial Business | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	3,575	4,064
Recorded Investment, With No Allocated Allowance	120	1,670
Allowance on Impaired Loans	(875)	(130)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	3,795	5,041
Unpaid Contractual Principal Balance, With No Related Allowance	1,413	2,681
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	3,490	5,380	1,111
Average Recorded Investment, With No Related Allowance	1,034	4,658	5,794
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	213	162	47
Interest Income Recognized during Impairment, With No Related Allowance	0	92	182
Trade Finance
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	103	0
Recorded Investment, With No Allocated Allowance	0	9,011
Allowance on Impaired Loans	0	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	103	0
Unpaid Contractual Principal Balance, With No Related Allowance	0	9,011
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	606	2,143	2,842
Average Recorded Investment, With No Related Allowance	4,127	5,405	2,994
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	2	0	217
Interest Income Recognized during Impairment, With No Related Allowance	0	487	253
Trade Finance | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	0
Recorded Investment, With No Allocated Allowance	0	3,124
Allowance on Impaired Loans	0	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	0	0
Unpaid Contractual Principal Balance, With No Related Allowance	0	3,124
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	0	0
Average Recorded Investment, With No Related Allowance	1,902	3,134	1,274
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	189	248
Consumer and Other
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	1,501	575
Recorded Investment, With No Allocated Allowance	1,553	1,007
Allowance on Impaired Loans	(17)	(3)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	1,581	575
Unpaid Contractual Principal Balance, With No Related Allowance	1,577	1,156
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	1,010	710	240
Average Recorded Investment, With No Related Allowance	1,515	1,457	1,225
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	4	7	4
Interest Income Recognized during Impairment, With No Related Allowance	0	0	25
Consumer and Other | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	738	144
Recorded Investment, With No Allocated Allowance	114	997
Allowance on Impaired Loans	(6)	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	781	144
Unpaid Contractual Principal Balance, With No Related Allowance	137	1,144
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	255	89	0
Average Recorded Investment, With No Related Allowance	649	1,298	645
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	7	0
Interest Income Recognized during Impairment, With No Related Allowance	0	0	7
Real estate-Commercial
Impaired Loans, Recorded Investment
Allowance on Impaired Loans	(312)	(437)
Real estate-Commercial | Retail
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	2,593	1,375
Recorded Investment, With No Allocated Allowance	4,557	8,005
Allowance on Impaired Loans	(66)	(156)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	2,904	1,487
Unpaid Contractual Principal Balance, With No Related Allowance	5,027	11,234
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	2,105	3,554	1,120
Average Recorded Investment, With No Related Allowance	10,657	9,913	12,288
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	48	30	0
Interest Income Recognized during Impairment, With No Related Allowance	172	143	434
Real estate-Commercial | Retail | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	759	198
Recorded Investment, With No Allocated Allowance	3,635	3,285
Allowance on Impaired Loans	(20)	(118)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	833	220
Unpaid Contractual Principal Balance, With No Related Allowance	3,833	4,151
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	646	510	851
Average Recorded Investment, With No Related Allowance	4,913	3,202	2,866
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	172	123	141
Real estate-Commercial | Hotel & Motel
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	1,877	1,949
Recorded Investment, With No Allocated Allowance	9,024	10,877
Allowance on Impaired Loans	(65)	(119)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	5,925	2,310
Unpaid Contractual Principal Balance, With No Related Allowance	16,831	22,590
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	1,723	2,700	4,050
Average Recorded Investment, With No Related Allowance	9,917	6,085	7,245
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	67
Interest Income Recognized during Impairment, With No Related Allowance	0	0	0
Real estate-Commercial | Hotel & Motel | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	54	72
Recorded Investment, With No Allocated Allowance	5,003	5,428
Allowance on Impaired Loans	(1)	(4)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	345	345
Unpaid Contractual Principal Balance, With No Related Allowance	6,681	6,874
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	65	78	105
Average Recorded Investment, With No Related Allowance	5,287	2,685	3,086
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	0	0
Real estate-Commercial | Gas Station & Car Wash
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	54	0
Recorded Investment, With No Allocated Allowance	217	545
Allowance on Impaired Loans	(2)	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	55	0
Unpaid Contractual Principal Balance, With No Related Allowance	2,671	3,653
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	35	0	43
Average Recorded Investment, With No Related Allowance	433	520	3,168
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	19	0
Real estate-Commercial | Gas Station & Car Wash | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	54	0
Recorded Investment, With No Allocated Allowance	217	247
Allowance on Impaired Loans	(2)	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	55	0
Unpaid Contractual Principal Balance, With No Related Allowance	2,671	2,673
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	35	0	0
Average Recorded Investment, With No Related Allowance	215	176	619
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	0	0
Real estate-Commercial | Mixed Use
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	611	881
Recorded Investment, With No Allocated Allowance	3,229	7,048
Allowance on Impaired Loans	(10)	(43)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	709	947
Unpaid Contractual Principal Balance, With No Related Allowance	3,246	7,058
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	763	2,032	245
Average Recorded Investment, With No Related Allowance	4,844	3,404	3,496
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	6	6	6
Interest Income Recognized during Impairment, With No Related Allowance	198	347	0
Real estate-Commercial | Mixed Use | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	273	312
Recorded Investment, With No Allocated Allowance	0	3,722
Allowance on Impaired Loans	(9)	(38)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	282	312
Unpaid Contractual Principal Balance, With No Related Allowance	0	3,726
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	293	1,813	179
Average Recorded Investment, With No Related Allowance	1,564	789	2,191
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	6	6	6
Interest Income Recognized during Impairment, With No Related Allowance	0	148	0
Real estate-Commercial | Industrial & Warehouse
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	8,168	1,305
Recorded Investment, With No Allocated Allowance	12,757	12,343
Allowance on Impaired Loans	(155)	(93)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	9,481	2,139
Unpaid Contractual Principal Balance, With No Related Allowance	14,261	13,467
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	6,465	1,579	1,135
Average Recorded Investment, With No Related Allowance	11,168	11,560	8,676
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	351	70	0
Interest Income Recognized during Impairment, With No Related Allowance	206	298	262
Real estate-Commercial | Industrial & Warehouse | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	229	230
Recorded Investment, With No Allocated Allowance	93	119
Allowance on Impaired Loans	(74)	(88)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	1,012	1,050
Unpaid Contractual Principal Balance, With No Related Allowance	894	894
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	269	246	225
Average Recorded Investment, With No Related Allowance	61	253	59
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	0	3
Real estate-Commercial | Other
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	2,636	7,759
Recorded Investment, With No Allocated Allowance	8,710	5,969
Allowance on Impaired Loans	(14)	(26)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	2,902	8,174
Unpaid Contractual Principal Balance, With No Related Allowance	13,811	7,122
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	3,337	6,038	11,707
Average Recorded Investment, With No Related Allowance	10,880	13,107	17,116
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	88	372	237
Interest Income Recognized during Impairment, With No Related Allowance	260	106	608
Real estate-Commercial | Other | Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	1,712	3,454
Recorded Investment, With No Allocated Allowance	5,186	1,013
Allowance on Impaired Loans	(4)	(13)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	1,712	3,454
Unpaid Contractual Principal Balance, With No Related Allowance	9,279	1,326
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	1,142	2,133	319
Average Recorded Investment, With No Related Allowance	4,180	4,662	5,190
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	71	221	17
Interest Income Recognized during Impairment, With No Related Allowance	$ 260	$ 39	$ 340