Commitments and Contingencies, Consolidated Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Consolidated Lease Expense [Abstract]
Non-cash lease expense (amortization of ROU assets)	$ 10.0	$ 11.0
Related accretion expense on lease liability balances	3.4	2.4
Total fixed lease expense	13.4	13.4
Variable lease expense	0.2	1.8
Subtotal operating lease expense	13.6	15.2
Short-term operating leases	13.2	11.8
Total operating lease expense	26.8	27.0
Cash payments for operating lease liabilities	10.1	9.9
Operating lease income	$ 3.5	$ 4.8