Employee Benefit Plans (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Expected Amortization Of Pre Merger Regulatory Asset				$ 600
Amortization of prior service cost		$ (19)	$ (19)	(58)	$ (58)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		257	208	793	680
Defined Benefit Plan Amounts Recognized Gain (Loss)		238	189	735	622
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	134	119	422	377
Defined Benefit Plan Amounts Recognized From Regulatory Asset		104	70	313	245
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer				1,100
Interest cost		104	94	314	288
Expected return on plan assets		(127)	(131)	(381)	(406)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		101	82	304	258
Net periodic cost (benefit)	[1]	78	45	237	140
Total periodic cost		78	45	237	140
Defined Benefit Plan Amounts Recognized Gain (Loss)		101	82	304	258
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	101	82	304	258
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		300		900
Expected Amortization Of Pre Merger Regulatory Asset						$ 600
Interest cost		614	570	1,844	1,754
Expected return on plan assets		(693)	(770)	(2,079)	(2,318)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		128	86	386	302
Net periodic cost (benefit)	[1]	49	(114)	151	(262)
Amortization of pre-merger regulatory asset		162	191	543	571
Total periodic cost		211	77	694	309
Defined Benefit Plan Amounts Recognized Gain (Loss)		128	86	386	302
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	24	16	73	57
Defined Benefit Plan Amounts Recognized From Regulatory Asset		104	70	313	245
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		16	21	58	63
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		17	25	68	75
Net periodic cost (benefit)	[1]	33	46	126	138
Defined Benefit Plan, Benefit Obligation, Payment for Settlement		58		58
Total periodic cost		91	46	184	138
Defined Benefit Plan Amounts Recognized Gain (Loss)		17	25	68	75
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	17	25	68	75
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		10	10	29	29
Amortization of prior service cost		(19)	(19)	(58)	(58)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		11	15	35	45
Net periodic cost (benefit)	[1]	2	6	6	16
Total periodic cost		2	6	6	16
Defined Benefit Plan Amounts Recognized Gain (Loss)		(8)	(4)	(23)	(13)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	(8)	(4)	(23)	(13)
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		12	12	36	38
Net periodic cost (benefit)	[1]	12	12	36	38
Amortization of pre-merger regulatory asset		2	2	6	6
Total periodic cost		$ 14	$ 14	$ 42	$ 44

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