Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions		Total		Florida City Gas	Common Stock [Member]		Common Stock [Member] Florida City Gas	[1]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Florida City Gas	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Deferred Compensation [Member]	Treasury Stock, Common
Shares, Issued	[1],[2]				17,655,000
Stockholders' Equity Attributable to Parent		$ 774.2	[2]		$ 8.6	[1]			$ 371.2		$ 393.1	$ 1.3	$ 7.2	$ (7.2)
Net Income		89.8									89.8
Other comprehensive loss		(2.7)										(2.7)
Dividends		(37.4)									(37.4)
Stock Issued, Value, During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan	[1],[3]				$ 0.0
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan	[1],[2],[3]				39,000
Stock Issued During The Period Value Retirement Savings Plan And Dividend Reinvestment Plan	[3]	5.3							5.3
Share-based compensation, shares	[1],[2],[4],[5]				47,000
Share-based compensation	[4],[5]	3.5			$ 0.0	[1]			3.5					0.0
Treasury stock activities	[2]	$ 0.0											(0.1)	0.1
Common Stock, Dividends, Per Share, Declared		$ 2.0850
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		22,000
Shares, Issued	[1],[2]				17,741,000
Stockholders' Equity Attributable to Parent		$ 832.7	[2]		$ 8.6	[1]			380.0		445.5	(1.4)	7.1	(7.1)
Net Income		87.2									87.2
Stock Issued During Period, Value, Acquisitions				$ 366.5			$ 2.2			$ 364.3
Other comprehensive loss		(1.4)										(1.4)
Dividends		(44.0)									(44.0)
Share-based compensation, shares	[1],[2],[4],[5]				55,000
Share-based compensation	[4],[5]	5.1			$ 0.0	[1]			5.1
Treasury stock activities	[2]	$ 0.0											2.0	(2.0)
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	[1],[2]			4,439,000
Common Stock, Dividends, Per Share, Declared		$ 2.3050
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		20,000
Shares, Issued	[1],[2]				22,235,000
Stockholders' Equity Attributable to Parent		$ 1,246.1			$ 10.8	[1]			749.4		488.7	(2.8)	9.1	(9.1)
Preferred Stock, Shares Authorized		2,000,000
Net Income		$ 118.6									118.6
Other comprehensive loss		1.1										1.1
Dividends		(57.0)									(57.0)
Stock Issued, Value, During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan	[3]	74.5			$ 0.3	[1]			74.2
Stock Issued During The Period Shares Retirement Savings Plan And Dividend Reinvestment Plan	[1],[2],[3]				627,000
Share-based compensation, shares	[1],[2],[4],[5]				37,000
Share-based compensation	[4],[5]	6.9			$ 0.0	[1]			6.9
Treasury stock activities	[2]	$ 0.0											0.7	(0.7)
Common Stock, Dividends, Per Share, Declared		$ 2.5100
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		14,000
Shares, Issued	[1],[2]				22,899,000
Stockholders' Equity Attributable to Parent		$ 1,390.2			$ 11.1	[1]			$ 830.5		$ 550.3	$ (1.7)	$ 9.8	$ (9.8)
Preferred Stock, Shares Authorized		2,000,000.0

[1] 2.0 million shares of preferred stock at $0.01 par value per share have been authorized. No preferred shares have been issued or are outstanding; accordingly, no information has been included in the Consolidated Statements of Stockholders’ Equity.

[2] Includes 114 thousand, 108 thousand and 108 thousand shares at December 31, 2024, 2023 and 2022, respectively, held in a Rabbi Trust related to our Non-Qualified Deferred Compensation Plan

[3] Includes shares issued under the Retirement Savings Plan, DRIP and/or ATM, as applicable.

[4] Includes amounts for shares issued for directors’ compensation.

[5] The shares issued under the SICP are net of shares withheld for employee taxes. For 2024, 2023 and 2022, we withheld 14 thousand, 20 thousand and 22 thousand shares, respectively, for taxes.