Loans Receivable and Allowance for Loan Losses - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	$ 36,047	$ 31,658
Recorded Investment, With No Allocated Allowance	67,960	82,691
Allowance on Impaired Loans	(4,791)	(5,323)
Impaired Loans, net of allowance	99,216	109,026
Impaired Financing Receivable, Recorded Investment	104,007	114,349
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	39,560	39,604
Unpaid Contractual Principal Balance, With No Related Allowance	93,141	96,817
Impaired Financing Receivable, Unpaid Principal Balance	132,701	136,421
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	41,952	45,077	$ 70,958
Average Recorded Investment, With No Related Allowance	70,012	75,236	65,752
Average Recorded Investment, Total	111,964	120,313	136,710
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	996	1,162	2,412
Interest Income Recognized during Impairment, With No Related Allowance	1,931	2,279	2,174
Interest Income Recognized during Impairment, Total	2,927	3,441	4,586
Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	8,474	3,003
Recorded Investment, With No Allocated Allowance	19,605	34,124
Allowance on Impaired Loans	(391)	(1,100)
Impaired Financing Receivable, Recorded Investment	28,079	37,127
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	10,566	4,598
Unpaid Contractual Principal Balance, With No Related Allowance	26,593	39,468
Impaired Financing Receivable, Unpaid Principal Balance	37,159	44,066
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	10,299	2,790	2,677
Average Recorded Investment, With No Related Allowance	20,857	21,959	17,003
Average Recorded Investment, Total	31,156	24,749	19,680
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	396	70	30
Interest Income Recognized during Impairment, With No Related Allowance	591	921	641
Interest Income Recognized during Impairment, Total	987	991	671
WIthout charge-offs
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	35,365	28,614
Recorded Investment, With No Allocated Allowance	59,607	77,533
With charge-offs
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	681	3,044
Recorded Investment, With No Allocated Allowance	8,354	5,158
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	50	0	0
Average Recorded Investment, With No Related Allowance	0	1,105	712
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	119
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	50	0	0
Average Recorded Investment, With No Related Allowance	0	235	136
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	0	1,300
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	1,441
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	0	0
Average Recorded Investment, With No Related Allowance	520	1,611	1,322
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	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	0	0
Average Recorded Investment, With No Related Allowance	0	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	22,203	18,330
Recorded Investment, With No Allocated Allowance	13,155	31,725
Allowance on Impaired Loans	(4,351)	(3,661)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	23,928	22,757
Unpaid Contractual Principal Balance, With No Related Allowance	17,850	33,207
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	23,146	23,695	32,626
Average Recorded Investment, With No Related Allowance	18,041	16,312	10,559
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	511	631	988
Interest Income Recognized during Impairment, With No Related Allowance	531	697	203
Commercial Business \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	4,064	1,987
Recorded Investment, With No Allocated Allowance	1,670	16,746
Allowance on Impaired Loans	(130)	(854)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	5,041	2,903
Unpaid Contractual Principal Balance, With No Related Allowance	2,681	16,926
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	5,380	1,111	448
Average Recorded Investment, With No Related Allowance	4,658	5,794	580
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	162	47	5
Interest Income Recognized during Impairment, With No Related Allowance	92	182	2
Trade Finance
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	3,861
Recorded Investment, With No Allocated Allowance	9,011	3,074
Allowance on Impaired Loans	0	(3)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	0	3,861
Unpaid Contractual Principal Balance, With No Related Allowance	9,011	3,091
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	2,143	2,842	7,134
Average Recorded Investment, With No Related Allowance	5,405	2,994	1,674
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	217	25
Interest Income Recognized during Impairment, With No Related Allowance	487	253	208
Trade Finance \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	0
Recorded Investment, With No Allocated Allowance	3,124	2,984
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	3,124	3,001
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	0	0
Average Recorded Investment, With No Related Allowance	3,134	1,274	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	189	248	0
Consumer and Other
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	575	523
Recorded Investment, With No Allocated Allowance	1,007	1,556
Allowance on Impaired Loans	(3)	(35)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	575	524
Unpaid Contractual Principal Balance, With No Related Allowance	1,156	1,676
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	710	240	289
Average Recorded Investment, With No Related Allowance	1,457	1,225	1,026
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	7	4	4
Interest Income Recognized during Impairment, With No Related Allowance	0	25	29
Consumer and Other \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	144	0
Recorded Investment, With No Allocated Allowance	997	1,171
Allowance on Impaired Loans	0	0
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	144	0
Unpaid Contractual Principal Balance, With No Related Allowance	1,144	1,291
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	89	0	32
Average Recorded Investment, With No Related Allowance	1,298	645	453
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	7	0	0
Interest Income Recognized during Impairment, With No Related Allowance	0	7	9
Real estate-Commercial
Impaired Loans, Recorded Investment
Allowance on Impaired Loans	(437)	(1,624)
Real estate-Commercial \| Retail
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	1,375	532
Recorded Investment, With No Allocated Allowance	8,005	11,792
Allowance on Impaired Loans	(156)	(131)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	1,487	531
Unpaid Contractual Principal Balance, With No Related Allowance	11,234	13,923
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	3,554	1,120	1,788
Average Recorded Investment, With No Related Allowance	9,913	12,288	10,745
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	30	0	0
Interest Income Recognized during Impairment, With No Related Allowance	143	434	451
Real estate-Commercial \| Retail \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	198	262
Recorded Investment, With No Allocated Allowance	3,285	3,412
Allowance on Impaired Loans	(118)	(126)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	220	261
Unpaid Contractual Principal Balance, With No Related Allowance	4,151	4,099
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	510	851	1,387
Average Recorded Investment, With No Related Allowance	3,202	2,866	2,496
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	123	141	152
Real estate-Commercial \| Hotel & Motel
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	1,949	2,931
Recorded Investment, With No Allocated Allowance	10,877	2,841
Allowance on Impaired Loans	(119)	(284)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	2,310	5,090
Unpaid Contractual Principal Balance, With No Related Allowance	22,590	5,288
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	2,700	4,050	3,650
Average Recorded Investment, With No Related Allowance	6,085	7,245	8,275
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	0	67	332
Interest Income Recognized during Impairment, With No Related Allowance	0	0	14
Real estate-Commercial \| Hotel & Motel \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	72	85
Recorded Investment, With No Allocated Allowance	5,428	482
Allowance on Impaired Loans	(4)	(2)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	345	86
Unpaid Contractual Principal Balance, With No Related Allowance	6,874	1,887
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	78	105	0
Average Recorded Investment, With No Related Allowance	2,685	3,086	5,700
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	14
Real estate-Commercial \| Gas Station & Car Wash
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	0
Recorded Investment, With No Allocated Allowance	545	591
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	3,653	1,764
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	43	884
Average Recorded Investment, With No Related Allowance	520	3,168	4,817
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	19	0	39
Real estate-Commercial \| Gas Station & Car Wash \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	0	0
Recorded Investment, With No Allocated Allowance	247	1
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	2,673	28
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	0	0	203
Average Recorded Investment, With No Related Allowance	176	619	1,506
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	39
Real estate-Commercial \| Mixed Use
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	881	312
Recorded Investment, With No Allocated Allowance	7,048	1,101
Allowance on Impaired Loans	(43)	(4)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	947	958
Unpaid Contractual Principal Balance, With No Related Allowance	7,058	3,490
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	2,032	245	350
Average Recorded Investment, With No Related Allowance	3,404	3,496	3,284
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	6	6	7
Interest Income Recognized during Impairment, With No Related Allowance	347	0	282
Real estate-Commercial \| Mixed Use \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	312	129
Recorded Investment, With No Allocated Allowance	3,722	152
Allowance on Impaired Loans	(38)	(1)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	312	129
Unpaid Contractual Principal Balance, With No Related Allowance	3,726	2,240
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	1,813	179	280
Average Recorded Investment, With No Related Allowance	789	2,191	1,238
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	6	6	7
Interest Income Recognized during Impairment, With No Related Allowance	148	0	245
Real estate-Commercial \| Industrial & Warehouse
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	1,305	772
Recorded Investment, With No Allocated Allowance	12,343	8,429
Allowance on Impaired Loans	(93)	(96)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	2,139	1,482
Unpaid Contractual Principal Balance, With No Related Allowance	13,467	8,525
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	1,579	1,135	547
Average Recorded Investment, With No Related Allowance	11,560	8,676	10,252
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	70	0	23
Interest Income Recognized during Impairment, With No Related Allowance	298	262	350
Real estate-Commercial \| Industrial & Warehouse \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	230	221
Recorded Investment, With No Allocated Allowance	119	45
Allowance on Impaired Loans	(88)	(96)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	1,050	896
Unpaid Contractual Principal Balance, With No Related Allowance	894	45
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	246	225	0
Average Recorded Investment, With No Related Allowance	253	59	873
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	3	3
Real estate-Commercial \| Other
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	7,759	4,397
Recorded Investment, With No Allocated Allowance	5,969	20,282
Allowance on Impaired Loans	(26)	(1,109)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	8,174	4,401
Unpaid Contractual Principal Balance, With No Related Allowance	7,122	24,412
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	6,038	11,707	23,690
Average Recorded Investment, With No Related Allowance	13,107	17,116	13,086
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	372	237	1,033
Interest Income Recognized during Impairment, With No Related Allowance	106	608	479
Real estate-Commercial \| Other \| Acquired
Impaired Loans, Recorded Investment
Recorded Investment, With Allocated Allowance	3,454	319
Recorded Investment, With No Allocated Allowance	1,013	9,131
Allowance on Impaired Loans	(13)	(21)
Impaired Loans, Unpaid Principal Balance
Unpaid Contractual Principal Balance, With Related Allowance	3,454	323
Unpaid Contractual Principal Balance, With No Related Allowance	1,326	9,951
Impaired Loans, Average Recorded Investment
Average Recorded Investment, With Related Allowance	2,133	319	327
Average Recorded Investment, With No Related Allowance	4,662	5,190	4,021
Impaired Loans, Interest Income Recognized during Impairment
Interest Income Recognized during Impairment, With Related Allowance	221	17	18
Interest Income Recognized during Impairment, With No Related Allowance	$ 39	$ 340	$ 177

Loans Receivable and Allowance for Loan Losses - Impaired Financing Receivables (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Impaired Loans, Recorded Investment

Recorded Investment, With Allocated Allowance

$ 36,047

$ 31,658

Recorded Investment, With No Allocated Allowance

67,960

82,691