Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Net income	$ 24.7	$ 26.6	$ 156.2	$ 143.9
Other comprehensive income (loss), net of tax:
Reclassification adjustments of benefit plan liability - net loss (net of tax of $0.0, $0.0, $0.0, and $0.0, respectively)	0.0	0.0	0.1	0.0
Net unrealized gains (losses) on commodity derivatives (net of tax of $0.0, $0.0, $0.0, and $0.2, respectively)	0.0	0.1	(0.2)	(0.7)
Other comprehensive income, net of tax	1.0	1.0	3.5	2.3
Comprehensive income	25.7	27.6	159.7	146.2
Less: comprehensive income attributable to non-controlling interest	(1.9)	(3.5)	(5.6)	(6.8)
Comprehensive income available for common stock	23.8	24.1	154.1	139.4
Interest rate swaps
Other comprehensive income (loss), net of tax:
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, after tax	0.6	0.5	1.1	1.1
Commodity derivatives
Other comprehensive income (loss), net of tax:
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, after tax	$ 0.4	$ 0.4	$ 2.5	$ 1.9