Employee Benefit Plans (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost		$ (19)	$ (19)
Defined Benefit Plan Actuarial Gain Loss, Net Settlement			198
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		228	217
Defined Benefit Plan Amounts Recognized Gain (Loss)		209	198
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	85	89
Defined Benefit Plan Amounts Recognized From Regulatory Asset		124	109
Defined Benefit Plan, Expected Future Benefit Payment, Remainder of Fiscal Year		700
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		100
Interest cost		34	46
Expected return on plan assets		(40)	(42)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		60	65
Net periodic cost (benefit)	[1]	54	69
Total periodic cost		54	69
Defined Benefit Plan Amounts Recognized Gain (Loss)		60	65
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	60	65
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		300
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		400
Interest cost		429	518
Expected return on plan assets		(830)	(745)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		155	135
Net periodic cost (benefit)	[1]	(246)	(92)
Amortization of pre-merger regulatory asset		0	0
Total periodic cost		(246)	(92)
Defined Benefit Plan Amounts Recognized Gain (Loss)		155	135
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	29	26
Defined Benefit Plan Amounts Recognized From Regulatory Asset		126	109
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		2,100
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		12	16
Defined Benefit Plan Actuarial Gain Loss, Net Settlement			5
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		7	5
Net periodic cost (benefit)	[1]	19	21
Total periodic cost		19	21
Defined Benefit Plan Amounts Recognized Gain (Loss)		7	5
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	7	5
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		200
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		200
Interest cost		6	8
Amortization of prior service cost		(19)	(19)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		8	12
Net periodic cost (benefit)	[1]	(5)	1
Total periodic cost		(5)	1
Defined Benefit Plan Amounts Recognized Gain (Loss)		(11)	(7)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	(11)	(7)
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		200
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		6	10
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		(2)
Net periodic cost (benefit)	[1]	4	10
Amortization of pre-merger regulatory asset		0	2
Total periodic cost		4	$ 12
Defined Benefit Plan Amounts Recognized Gain (Loss)		(2)
Defined Benefit Plan Amounts Recognized From Regulatory Asset		(2)
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		$ 100

[1] See Note 9, Stockholders' Equity.