Commitments and Contingencies, Consolidated Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Consolidated Lease Expense [Abstract]
Non-cash lease expense (amortization of ROU assets)	$ 9.8	$ 10.7	$ 19.8	$ 21.7
Related accretion expense on lease liability balances	3.3	2.4	6.7	4.8
Total fixed lease expense	13.1	13.1	26.5	26.5
Variable lease expense	0.1	1.1	0.3	2.9
Subtotal operating lease expense	13.2	14.2	26.8	29.4
Short-term operating leases	11.8	11.7	25.0	23.5
Total operating lease expense	25.0	25.9	51.8	52.9
Cash payments for operating lease liabilities	7.9	12.9	18.3	26.4
Operating lease income	$ 2.6	$ 2.4	$ 6.1	$ 7.2