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		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		$ (19)	$ (19)	$ (39)	$ (39)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		268	236	537	473
Recognized from accumulated other comprehensive loss	[1]	144	130	289	258
Recognized from regulatory asset		105	87	209	176
Total recognized in net periodic benefit cost		249	217	498	434
Chesapeake Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		101	88	203	176
Recognized from accumulated other comprehensive loss	[1]	101	88	203	176
Total recognized in net periodic benefit cost		101	88	203	176
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)		129	108	258	217
Recognized from accumulated other comprehensive loss	[1]	24	21	49	41
Recognized from regulatory asset		105	87	209	176
Total recognized in net periodic benefit cost		129	108	258	217
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		26	25	52	50
Recognized from accumulated other comprehensive loss	[1]	26	25	52	50
Total recognized in net periodic benefit cost		26	25	52	50
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		(19)	(19)	(39)	(39)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		12	15	24	30
Recognized from accumulated other comprehensive loss	[1]	(7)	(4)	(15)	(9)
Total recognized in net periodic benefit cost		$ (7)	$ (4)	$ (15)	$ (9)

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