Commitments and Contingencies, Consolidated Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Consolidated Lease Expense [Abstract]
Non-cash lease expense (amortization of ROU assets)	$ 9.8	$ 10.7	$ 29.6	$ 32.4
Related accretion expense on lease liability balances	3.1	2.1	9.8	6.9
Total fixed lease expense	12.9	12.8	39.4	39.3
Variable lease expense	0.1	1.6	0.4	4.5
Subtotal operating lease expense	13.0	14.4	39.8	43.8
Short-term operating leases	12.3	12.4	37.3	35.9
Total operating lease expense	25.3	26.8	77.1	79.7
Cash payments for operating lease liabilities	9.8	13.0	28.1	39.4
Operating lease income	2.3	$ 3.5	8.4	$ 10.7
Operating lease commitments	$ 469.2		$ 469.2		$ 271.2