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
		Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		$ (19)	$ (20)
Net loss		276	272
Recognized from accumulated other comprehensive loss	[1]	151	148
Recognized from regulatory asset		106	104
Total recognized in net periodic benefit cost		257	252
Chesapeake Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0
Net loss		107	104
Recognized from accumulated other comprehensive loss	[1]	107	104
Recognized from regulatory asset		0	0
Total recognized in net periodic benefit cost		107	104
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0
Net loss		131	128
Recognized from accumulated other comprehensive loss	[1]	25	24
Recognized from regulatory asset		106	104
Total recognized in net periodic benefit cost		131	128
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0
Net loss		22	22
Recognized from accumulated other comprehensive loss	[1]	22	22
Recognized from regulatory asset		0	0
Total recognized in net periodic benefit cost		22	22
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		(19)	(20)
Net loss		16	18
Recognized from accumulated other comprehensive loss	[1]	(3)	(2)
Recognized from regulatory asset		0	0
Total recognized in net periodic benefit cost		(3)	(2)
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0
Net loss		0	0
Recognized from accumulated other comprehensive loss	[1]	0	0
Recognized from regulatory asset		0	0
Total recognized in net periodic benefit cost		$ 0	$ 0

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