Employee Benefit Plans - Amounts Included in Regulatory Asset and Accumulated Other Comprehensive Income/Loss Recognized as Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		$ (19)	$ (19)	$ (58)	$ (58)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		257	208	793	680
Recognized from accumulated other comprehensive loss	[1]	134	119	422	377
Recognized from regulatory asset		104	70	313	245
Total recognized in net periodic benefit cost		238	189	735	622
Chesapeake Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		101	82	304	258
Recognized from accumulated other comprehensive loss	[1]	101	82	304	258
Total recognized in net periodic benefit cost		101	82	304	258
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		128	86	386	302
Recognized from accumulated other comprehensive loss	[1]	24	16	73	57
Recognized from regulatory asset		104	70	313	245
Total recognized in net periodic benefit cost		128	86	386	302
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		17	25	68	75
Recognized from accumulated other comprehensive loss	[1]	17	25	68	75
Total recognized in net periodic benefit cost		17	25	68	75
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		(19)	(19)	(58)	(58)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		11	15	35	45
Recognized from accumulated other comprehensive loss	[1]	(8)	(4)	(23)	(13)
Total recognized in net periodic benefit cost		$ (8)	$ (4)	$ (23)	$ (13)

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