Loans Receivable and Allowance For Loan Losses - Aging Analysis of Past Due Loans) (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan	Jun. 30, 2019 USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 3,160	$ 4,159
Current	1,465,748	1,347,734
Total loans receivable	1,468,908	1,351,893	$ 1,296,121
REAL ESTATE LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	867,925	824,040	809,974
REAL ESTATE LOANS. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	867,925	824,040
Total real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,867	2,985
Current	866,058	821,055
Total loans receivable	867,925	824,040
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	222,265	210,749
Total loans receivable	222,265	210,749
Loans restructured or modified	53,000
Commercial Real Estate | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	222,265	210,749
Construction and development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	533
Current	183,029	179,121
Total loans receivable	183,029	179,654
Construction and development | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	183,029	179,654
Home equity.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	541	294
Current	34,541	37,873
Total loans receivable	35,082	38,167
Home equity. | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	35,082	38,167
One-to-four-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,326	2,158
Current	293,894	259,381
Total loans receivable	295,220	261,539
Loans restructured or modified	18,800
One-to-four-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	295,220	261,539
Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	132,329	133,931
Total loans receivable	132,329	133,931
Multi-family | REAL ESTATE LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	132,329	133,931
CONSUMER LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,293	1,174
Current	344,028	325,036
Total loans receivable	345,321	326,210	303,783
Loans restructured or modified	4,000
CONSUMER LOANS. | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	345,321	326,210
Indirect home improvement
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,160	1,066
Current	263,621	253,625
Total loans receivable	264,781	254,691
Indirect home improvement | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	264,781	254,691
Marine
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	85	15
Current	76,808	67,164
Total loans receivable	76,893	67,179
Marine | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	76,893	67,179
Other consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	48	93
Current	3,599	4,247
Total loans receivable	3,647	4,340
Other consumer loans | CONSUMER LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	3,647	4,340
COMMERCIAL BUSINESS LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	255,662	201,643
Total loans receivable	255,662	201,643	$ 182,364
Loans restructured or modified	24,100
COMMERCIAL BUSINESS LOANS. | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	255,662	201,643
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	213,961	140,531
Total loans receivable	213,961	140,531
Commercial and industrial | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	213,961	140,531
Warehouse lending
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	41,701	61,112
Total loans receivable	41,701	61,112
Warehouse lending | COMMERCIAL BUSINESS LOANS
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans receivable	41,701	61,112
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	619	2,314
30-59 Days Past Due | Total real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	14	1,536
30-59 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
30-59 Days Past Due | Construction and development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	533
30-59 Days Past Due | Home equity.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	14	109
30-59 Days Past Due | One-to-four-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	894
30-59 Days Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
30-59 Days Past Due | CONSUMER LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	605	778
30-59 Days Past Due | Indirect home improvement
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	568	692
30-59 Days Past Due | Marine
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	15
30-59 Days Past Due | Other consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	37	71
30-59 Days Past Due | COMMERCIAL BUSINESS LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
30-59 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
30-59 Days Past Due | Warehouse lending
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	458	343
60-89 Days Past Due | Total real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	221	114
60-89 Days Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Construction and development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Home equity.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | One-to-four-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	221	114
60-89 Days Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | CONSUMER LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	237	229
60-89 Days Past Due | Indirect home improvement
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	230	227
60-89 Days Past Due | Marine
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Other consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7	2
60-89 Days Past Due | COMMERCIAL BUSINESS LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
60-89 Days Past Due | Warehouse lending
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 2,083	$ 1,502
Number Of Loans Accruing Interest | loan	0	0
90 Days or More Past Due | Total real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 1,632	$ 1,335
90 Days or More Past Due | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
90 Days or More Past Due | Construction and development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
90 Days or More Past Due | Home equity.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	527	185
90 Days or More Past Due | One-to-four-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,105	1,150
90 Days or More Past Due | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
90 Days or More Past Due | CONSUMER LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	451	167
90 Days or More Past Due | Indirect home improvement
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	362	147
90 Days or More Past Due | Marine
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	85	0
90 Days or More Past Due | Other consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4	20
90 Days or More Past Due | COMMERCIAL BUSINESS LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
90 Days or More Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
90 Days or More Past Due | Warehouse lending
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,897	3,033
Non-Accrual | Total real estate loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,889	2,540
Non-Accrual | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,094	1,086
Current	1,100
Non-Accrual | Construction and development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual | Home equity.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	690	190
Non-Accrual | One-to-four-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,105	1,264
Non-Accrual | Multi-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Non-Accrual | CONSUMER LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	746	493
Non-Accrual | Indirect home improvement
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	657	468
Non-Accrual | Marine
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	85	0
Non-Accrual | Other consumer loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4	25
Non-Accrual | COMMERCIAL BUSINESS LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,262	0
Current	4,300
Non-Accrual | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,262	0
Non-Accrual | Warehouse lending
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	$ 0
FHA Guidelines COVID 19 [Member] | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans restructured or modified	53,000
FHA Guidelines COVID 19 [Member] | One-to-four-family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans restructured or modified	18,800
FHA Guidelines COVID 19 [Member] | CONSUMER LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans restructured or modified	4,000
FHA Guidelines COVID 19 [Member] | COMMERCIAL BUSINESS LOANS.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans restructured or modified	$ 24,100