Share-based Payments - Employee Stock Purchase Plans (Details) - Employee Stock Purchase Plan - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Employee Stock Purchase Plans
Shares purchased under ESPP plan	20,128	23,789
Plan compensation expense	$ 9	$ 10

Number of shares issued during the period as a result of an employee stock purchase plan.

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Name:	us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration