Employee Benefit Plans (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost		$ (19)	$ (19)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		217	268
Defined Benefit Plan Amounts Recognized Gain (Loss)		198	249
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	89	144
Defined Benefit Plan Amounts Recognized From Regulatory Asset		109	105
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		300
Interest cost		46	105
Expected return on plan assets		(42)	(127)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		65	101
Net periodic cost (benefit)	[1]	69	79
Total periodic cost		69	79
Defined Benefit Plan Amounts Recognized Gain (Loss)		65	101
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	65	101
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		3,200
Defined Benefit Plan, Plan Assets, Contributions by Employer		300
Interest cost		518	615
Expected return on plan assets		(745)	(693)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		135	129
Net periodic cost (benefit)	[1]	(92)	51
Amortization of pre-merger regulatory asset		0	190
Total periodic cost		(92)	241
Defined Benefit Plan Amounts Recognized Gain (Loss)		135	129
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	26	24
Defined Benefit Plan Amounts Recognized From Regulatory Asset		109	105
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		200
Interest cost		16	21
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		5	26
Net periodic cost (benefit)	[1]	21	47
Total periodic cost		21	47
Defined Benefit Plan Amounts Recognized Gain (Loss)		5	26
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	5	26
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		100
Interest cost		8	10
Amortization of prior service cost		(19)	(19)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		12	12
Net periodic cost (benefit)	[1]	1	3
Total periodic cost		1	3
Defined Benefit Plan Amounts Recognized Gain (Loss)		(7)	(7)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	(7)	(7)
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		100
Interest cost		10	12
Net periodic cost (benefit)	[1]	10	12
Amortization of pre-merger regulatory asset		2	2
Total periodic cost		$ 12	$ 14

[1] See Note 9, Stockholder's Equity.