Loans and Allowance for Losses - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	$ 0	$ 17,000	$ 67,000	$ 17,000
Provision for/(release of) losses	760,000	99,000	1,074,000	92,000
Past due financing receivables	59,691,000		59,691,000		$ 26,881,000
Loans subject to removal-of-account provisions	0		0		100,000
Troubled debt restructurings, recorded investment	35,600,000		35,600,000
SEC Schedule, 12-09, Allowance, Loan and Lease Loss [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	0	17,000	67,000	17,000
Provision for/(release of) losses	760,000	99,000	1,074,000	92,000
SEC Schedule, 12-09, Reserve, Off-balance Sheet Activity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs	0	0	0	0
Provision for/(release of) losses	(137,000)	$ (102,000)	(424,000)	$ 77,000
On-balance sheet [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due financing receivables	$ 55,987,000		$ 55,987,000		$ 19,577,000