Commitments and Contingent Liabilities, Consolidated Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Consolidated Lease Expense [Abstract]
Non-cash lease expense (amortization of ROU assets)	$ 10.9	$ 9.8	$ 29.5	$ 29.6
Related accretion expense on lease liability balances	3.2	3.1	9.3	9.8
Total fixed lease expense	14.1	12.9	38.8	39.4
Variable lease expense	0.2	0.1	0.8	0.4
Subtotal operating lease expense	14.3	13.0	39.6	39.8
Short-term operating leases	15.0	12.3	41.4	37.3
Total operating lease expense	29.3	25.3	81.0	77.1
Cash payments for operating lease liabilities	10.8	9.8	29.2	28.1
Operating lease income	$ 3.1	$ 2.3	$ 9.2	$ 8.4