Basis of Presentation - Disaggregation of Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Revenue from External Customer [Line Items]
Operating Revenue		$ 1,260.4	$ 1,198.4
LTL revenue
Revenue from External Customer [Line Items]
Operating Revenue		1,129.6	1,083.5
Other revenue
Revenue from External Customer [Line Items]
Operating Revenue	[1]	$ 130.8	$ 114.9

[1] Other revenue is primarily comprised of truckload shipments by the LTL operating companies.