Summary of Significant Accounting Policies - Assets Held for Sale (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Long Lived Assets Held-for-sale
Impairment on assets held for sale	$ 0.0	$ 4.3	$ 14.3
Assets held for sale	0.7	18.8
Truckload
Long Lived Assets Held-for-sale
Assets held for sale	0.5	16.9
Intermodal
Long Lived Assets Held-for-sale
Assets held for sale	$ 0.2	1.9
FTFM service offering shutdown
Long Lived Assets Held-for-sale
Impairment on assets held for sale			28.1
Assets held for sale		1.6
Bulk sale of tractors
Long Lived Assets Held-for-sale
Impairment on assets held for sale			11.5
Non FTFM Shutdown and FTFM Shutdown
Long Lived Assets Held-for-sale
Impairment on assets held for sale		$ 4.7	$ 42.4