Loans Receivable and Allowance for Loan Losses, Loans modified as TDRs (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) loan contract	Mar. 31, 2019 loan contract	Dec. 31, 2019 USD ($) contract
Loans modified [Abstract]
Number of modifications | loan	0	0
TDRs loans accounted under method [Abstract]
Number of modifications	36		36
Accrual status | $	$ 8,786		$ 8,858
Number of modifications	1		1
Nonaccrual status | $	$ 85		$ 85
Total number of modifications	37		37
Total balance of modifications | $	$ 8,871		$ 8,943
Number of contract, subsequent defaults	0	0
Residential Mortgage [Member]
TDRs loans accounted under method [Abstract]
Number of modifications	31		31
Accrual status | $	$ 7,615		$ 7,675
Number of modifications	1		1
Nonaccrual status | $	$ 85		$ 85
Total number of modifications	32		32
Total balance of modifications | $	$ 7,700		$ 7,760
Commercial Real Estate [Member]
TDRs loans accounted under method [Abstract]
Number of modifications	2		2
Accrual status | $	$ 974		$ 984
Total number of modifications	2		2
Total balance of modifications | $	$ 974		$ 984
ADC [Member]
TDRs loans accounted under method [Abstract]
Number of modifications	1		1
Accrual status | $	$ 129		$ 130
Total number of modifications	1		1
Total balance of modifications | $	$ 129		$ 130
Consumer [Member]
TDRs loans accounted under method [Abstract]
Number of modifications	2		2
Accrual status | $	$ 68		$ 69
Total number of modifications	2		2
Total balance of modifications | $	$ 68		$ 69