Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts Receivable
Valuation and Qualifying Accounts and Reserves
Balance at beginning of period	$ 8.8	$ 8.7	$ 8.8
Charged to costs and expenses	0.1	0.1
Deductions/Applications	(0.2)		(0.1)
Balance at end of period	8.7	8.8	8.7
Notes issued under par
Valuation and Qualifying Accounts and Reserves
Balance at beginning of period	63.4	65.6	67.6
Charged to costs and expenses	2.1	2.2	2.0
Balance at end of period	61.3	63.4	65.6
Valuation allowance
Valuation and Qualifying Accounts and Reserves
Balance at beginning of period	2,053.7	1,820.0	1,343.2
Charged to costs and expenses	248.0	233.7	476.8
Balance at end of period	$ 2,301.7	$ 2,053.7	$ 1,820.0