Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents	$ 257.3		$ 42.0
Restricted cash included in Current Assets	0.1		0.5
Total cash, cash equivalents, and restricted cash	257.4	$ 51.9	$ 42.5	$ 49.4
Accrued purchases of property and equipment	8.7	26.2
Non-cash investing and financing activities related to property acquired under other financing arrangements	0.8	1.9
Adjustments to right-of use assets including right-of-use assets obtained in exchange for new operating lease liabilities	27.8	12.1
Adjustments to right-of use assets including right-of-use assets obtained in exchange for new finance lease liabilities	26.6	25.9
Interest payments, net of amounts capitalized and including interest on vehicle inventory financing	83.5	130.6
Income tax payments, net of income tax refunds	$ 3.2	$ 76.0