Employee Benefit Plans (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost		$ (19)	$ (19)	$ (57)	$ (58)
Defined Benefit Plan Actuarial Gain Loss, Net Settlement			128
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		217	257	651	683
Defined Benefit Plan, Benefit Obligation, Payment for Settlement			(58)		(58)
Defined Benefit Plan Amounts Recognized Gain (Loss)		198	238	594	625
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	89	24	267	312
Defined Benefit Plan Amounts Recognized From Regulatory Asset		109	104	327	313
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		100		300
Interest cost		46	104	138	314
Expected return on plan assets		(42)	(127)	(126)	(381)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		65	101	195	304
Net periodic cost (benefit)	[1]	69	78	207	237
Total periodic cost		69	78	207	237
Defined Benefit Plan Amounts Recognized Gain (Loss)		65	101	195	304
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	65	101	195	304
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		500		2,600
Interest cost		518	614	1,554	1,844
Expected return on plan assets		(745)	(693)	(2,235)	(2,079)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		135	128	405	386
Net periodic cost (benefit)	[1]	(92)	49	(276)	151
Amortization of pre-merger regulatory asset		0	162	0	543
Total periodic cost		(92)	211	(276)	694
Defined Benefit Plan Amounts Recognized Gain (Loss)		135	128	405	386
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	26	24	78	73
Defined Benefit Plan Amounts Recognized From Regulatory Asset		109	104	327	313
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		16	16	48	58
Defined Benefit Plan Actuarial Gain Loss, Net Settlement			(93)		(68)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		5	17	15	(42)
Net periodic cost (benefit)	[1]	21	33	63	126
Total periodic cost		21	91	63	184
Defined Benefit Plan Amounts Recognized Gain (Loss)		5	17	15	(42)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	5	(93)	15	(42)
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		8	10	24	29
Amortization of prior service cost		(19)	(19)	(57)	(58)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		12	11	36	35
Net periodic cost (benefit)	[1]	1	2	3	6
Total periodic cost		1	2	3	6
Defined Benefit Plan Amounts Recognized Gain (Loss)		(7)	(8)	(21)	(23)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	(7)	(8)	(21)	(23)
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		10	12	30	36
Net periodic cost (benefit)	[1]	10	12	30	36
Amortization of pre-merger regulatory asset		2	2	6	6
Total periodic cost		$ 12	$ 14	$ 36	$ 42

[1] See Note 9, Stockholders' Equity.