Note 6. Leases - Summary of future lease payments (Details) $ in Millions	Dec. 31, 2019 USD ($)
Leases [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 2.2
Lessee, Operating Lease, Liability, Payments, Due Year Two	4.5
Lessee, Operating Lease, Liability, Payments, Due Year Three	4.3
Lessee, Operating Lease, Liability, Payments, Due Year Four	3.8
Lessee, Operating Lease, Liability, Payments, Due Year Five	3.1
Lessee, Operating Lease, Liability, Payments, Due after Year Five	6.2
Lessee, Operating Lease, Liability, Payments, Due	24.1
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	3.1
Operating Lease, Liability	$ 21.0