Lease Accounting (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease costs		$ 18.4	$ 30.2	$ 27.2
Mileage credits		$ 20.8	18.4	$ 24.8
Fixed lease payments per year			$ 5.2
Fixed lease interest rate per year			10.25%
Early payment received on direct finance lease	$ 41.0
Direct finance lease receivable			$ 70.0