Summary of Accounting Policies - Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Activity in allowance for doubtful accounts
Balance at the beginning of the period	$ 5.0	$ 3.1
Current period provision	(0.3)	2.4
Amounts written off	(0.8)	(0.5)
Balance at the end of the period	3.9	5.0
Operating Segments | CCM
Activity in allowance for doubtful accounts
Balance at the beginning of the period	2.4	2.1
Current period provision	0.1	0.7
Amounts written off	(0.2)	(0.4)
Balance at the end of the period	2.3	2.4
Operating Segments | CWT
Activity in allowance for doubtful accounts
Balance at the beginning of the period	2.6	1.0
Current period provision	(0.4)	1.7
Amounts written off	(0.6)	(0.1)
Balance at the end of the period	$ 1.6	$ 2.6