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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		$ (20)	$ (20)	$ (39)	$ (40)
Net loss		276	270	551	541
Recognized from accumulated other comprehensive loss	[1]	150	146	300	293
Recognized from regulatory asset		106	104	212	208
Total recognized in net periodic benefit cost		256	250	512	501
Chesapeake Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0	0	0
Net loss		106	103	213	206
Recognized from accumulated other comprehensive loss	[1]	106	103	213	206
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		106	103	213	206
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0	0	0
Net loss		131	128	262	257
Recognized from accumulated other comprehensive loss	[1]	25	24	50	49
Recognized from regulatory asset		106	104	212	208
Total recognized in net periodic benefit cost		131	128	262	257
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0	0	0
Net loss		22	22	44	44
Recognized from accumulated other comprehensive loss	[1]	22	22	44	44
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		22	22	44	44
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		(20)	(20)	(39)	(40)
Net loss		17	17	32	34
Recognized from accumulated other comprehensive loss	[1]	(3)	(3)	(7)	(6)
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		(3)	(3)	(7)	(6)
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0	0	0
Net loss		0	0	0	0
Recognized from accumulated other comprehensive loss	[1]	0	0	0	0
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		$ 0	$ 0	$ 0	$ 0

[1] See Note 7, Stockholder's Equity.