Leases - Operating lease maturities - Supplemental Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) item
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 1.1
Lease assets obtained in exchange for new lease liabilities (non-cash):
Operating	$ 0.1
Weighted average items:
Weighted average remaining lease term (in years), Operating leases	2 years 8 months 12 days
Weighted average remaining lease term (in years), Finance leases	1 year 4 months 24 days
Weighted average discount rate - operating leases	3.90%
Weighted average discount rate - finance leases	4.10%
Number of lease transactions with related parties | item	0