Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost		$ (19)	$ (19)	$ (57)	$ (57)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		230	217	690	651
Defined Benefit Plan Amounts Recognized Gain (Loss)		211	198	633	594
Recognized from accumulated other comprehensive loss	[1]	87	89	260	267
Recognized from regulatory asset		124	109	373	327
Defined Benefit Plan Actuarial Gain Loss, Net Settlement			198		594
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan		500		1,300
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		2,100		2,100
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		155	135	465	405
Defined Benefit Plan Amounts Recognized Gain (Loss)		155	135	465	405
Recognized from accumulated other comprehensive loss	[1]	29	26	87	78
Recognized from regulatory asset		126	109	378	327
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan		200		300
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		60	65	180	195
Defined Benefit Plan Amounts Recognized Gain (Loss)		60	65	180	195
Recognized from accumulated other comprehensive loss	[1]	60	65	180	195
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan		100
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		200		200
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		7	5	21	15
Defined Benefit Plan Amounts Recognized Gain (Loss)		7	5	21	15
Recognized from accumulated other comprehensive loss	[1]	7	5	21	15
Defined Benefit Plan Actuarial Gain Loss, Net Settlement			5		15
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan				200
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		200		200
Amortization of prior service cost		(19)	(19)	(57)	(57)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		10	12	30	36
Defined Benefit Plan Amounts Recognized Gain (Loss)		(9)	(7)	(27)	(21)
Recognized from accumulated other comprehensive loss	[1]	(9)	$ (7)	(27)	$ (21)
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan				100
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		100		100
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		(2)		(6)
Defined Benefit Plan Amounts Recognized Gain (Loss)		(2)		(6)
Recognized from accumulated other comprehensive loss	[1]			(1)
Recognized from regulatory asset		$ (2)		$ (5)

[1] See Note 9, Stockholders' Equity.