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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		$ (19)	$ (19)	$ (38)	$ (39)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		217	268	434	537
Recognized from accumulated other comprehensive loss	[1]	89	144	178	289
Recognized from regulatory asset		109	105	218	209
Total recognized in net periodic benefit cost		198	249	396	498
Chesapeake Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		65	101	130	203
Recognized from accumulated other comprehensive loss	[1]	65	101	130	203
Total recognized in net periodic benefit cost		65	101	130	203
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)		135	129	270	258
Recognized from accumulated other comprehensive loss	[1]	26	24	52	49
Recognized from regulatory asset		109	105	218	209
Total recognized in net periodic benefit cost		135	129	270	258
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		5	26	10	52
Recognized from accumulated other comprehensive loss	[1]	5	26	10	52
Total recognized in net periodic benefit cost		5	26	10	52
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		(19)	(19)	(38)	(39)
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)		12	12	24	24
Recognized from accumulated other comprehensive loss	[1]	(7)	(7)	(14)	(15)
Total recognized in net periodic benefit cost		$ (7)	$ (7)	$ (14)	$ (15)

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