Commitments and Contingencies, Consolidated Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Consolidated Lease Expense [Abstract]
Non-cash lease expense (amortization of ROU assets)	$ 9.3	$ 10.0
Related accretion expense on lease liability balances	3.1	3.4
Total fixed lease expense	12.4	13.4
Variable lease expense	0.4	0.2
Subtotal operating lease expense	12.8	13.6
Short-term operating leases	13.5	13.2
Total operating lease expense	26.3	26.8
Cash payments for operating lease liabilities	9.1	10.1
Operating lease income	$ 3.0	$ 3.5