Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended			28 Months Ended
	Sep. 30, 2013	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Commitments and Contingencies (Details) [Line Items]
Operating Lease, Weighted Average Remaining Lease Term		37 years 7 months 6 days
Operating Lease, Weighted Average Discount Rate, Percent		5.20%
Operating lease, rent expense		$ 1,600	$ 1,900	$ 1,500
Tax protection agreements, period (in years)					10 years
Litigation settlement, amount awarded to other party		1,400
Litigation settlement expense		$ 950
Terranomics Crossroads Associates LP Member and SARM Five Points LLC
Commitments and Contingencies (Details) [Line Items]
Tax protection agreements, period (in years)	12 years