CAPITAL CONSTRUCTION FUND - Summary of the activities within the CCF Assigned Accounts Receivable account (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
CAPITAL CONSTRUCTION FUND
CCF assigned accounts receivable balance at beginning of period	$ 218.1	$ 9.9
Assigned accounts receivable		200.0
Interest earned on assigned accounts receivable	10.2	3.3
CCF assigned accounts receivable balance at end of period	$ 228.3	$ 213.2