Commitments and Contingences (Maturity analysis of operating lease liabilities) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Within one year	$ 704
After one but within two years	616
After two but within three years	608
After three but within four years	616
After four but within five years	634
After five years	8,450
Total undiscounted cash flows	11,628
Discount on cash flows	3,332
Total lease liability	$ 8,296	$ 8,495
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term	18 years 6 months	18 years 9 months 18 days
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year 2 months 12 days	0 years
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	25 years	25 years