Share-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		9 Months Ended
	May 01, 2025	Sep. 30, 2025	Sep. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		8,000	14,000
Payment, Tax Withholding, Share-based Payment Arrangement		$ 1.0	$ 1.5
Unrecognized compensation cost		7.7
Awards to non-employee directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 134.05
Granted awards (shares)	1,000
Unrecognized compensation expense related to the awards to non-employee directors		$ 0.6
Shares awarded to non-employee directors [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 134.05
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	1,000
Award to key employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Expired In Period		(26,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 125.56
Granted awards (shares)		99,000
Vesting period		3 years
Payment, Tax Withholding, Share-based Payment Arrangement		$ 1.0
Intrinsic value of the SICP awards		$ 39.0
Shares awarded to non-employee directors [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 125.56
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		99,000
Accelerated Vested Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation		8,000

CHESAPEAKE UTILITIES CORP 10-Q