Leases - Lease Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Leases
Minimum rental expense	$ 110,000	$ 110,000
Lease costs:
Operating lease costs	3,130,000
Short-term lease costs	57,000
Variable lease costs	129,000
Total lease costs	3,316,000
Rental expense, minimum rentals	$ 15,178,000	$ 3,100,000