Employee Benefit Plans (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer				$ 100
Expected Amortization Of Pre Merger Regulatory Asset				600
Amortization of prior service cost		$ (19)	$ (19)	(39)	$ (39)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		268	236	537	473
Defined Benefit Plan Amounts Recognized Gain (Loss)		249	217	498	434
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	144	130	289	258
Defined Benefit Plan Amounts Recognized From Regulatory Asset		105	87	209	176
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer				100
Interest cost		104	98	209	195
Expected return on plan assets		(127)	(138)	(254)	(276)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		101	88	203	176
Net periodic cost (benefit)	[1]	78	48	158	95
Total periodic cost		78	48	158	95
Defined Benefit Plan Amounts Recognized Gain (Loss)		101	88	203	176
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	101	88	203	176
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Contributions by Employer		400		600
Expected Amortization Of Pre Merger Regulatory Asset		200		200		$ 600
Interest cost		615	592	1,230	1,184
Expected return on plan assets		(693)	(774)	(1,386)	(1,549)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		129	108	258	217
Net periodic cost (benefit)	[1]	51	(74)	102	(148)
Amortization of pre-merger regulatory asset		191	191	381	381
Total periodic cost		242	117	483	233
Defined Benefit Plan Amounts Recognized Gain (Loss)		129	108	258	217
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	24	21	49	41
Defined Benefit Plan Amounts Recognized From Regulatory Asset		105	87	209	176
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		21	21	42	42
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		26	25	52	50
Net periodic cost (benefit)	[1]	47	46	94	92
Total periodic cost		47	46	94	92
Defined Benefit Plan Amounts Recognized Gain (Loss)		26	25	52	50
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	26	25	52	50
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		9	9	19	19
Amortization of prior service cost		(19)	(19)	(39)	(39)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		12	15	24	30
Net periodic cost (benefit)	[1]	2	5	4	10
Total periodic cost		2	5	4	10
Defined Benefit Plan Amounts Recognized Gain (Loss)		(7)	(4)	(15)	(9)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	(7)	(4)	(15)	(9)
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost		12	13	24	26
Net periodic cost (benefit)	[1]	12	13	24	26
Amortization of pre-merger regulatory asset		2	2	4	4
Total periodic cost		$ 14	$ 15	$ 28	$ 30

[1] See Note 8, Stockholder's Equity.