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, 2016		Jun. 30, 2015		Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	$ (20)		$ (17)		$ (40)	$ (34)
Net loss	270		249		541	496
Recognized from accumulated other comprehensive loss	146	[1]	138	[1]	293	276	[1]
Recognized from regulatory asset	104		94		208	186
Total recognized in net periodic benefit cost	250		232		501	462
Chesapeake Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	0		0		0	0
Net loss	103		91		206	181
Recognized from accumulated other comprehensive loss	103	[1]	91	[1]	206	181	[1]
Recognized from regulatory asset	0		0		0	0
Total recognized in net periodic benefit cost	103		91		206	181
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	128		114		257	227
Recognized from accumulated other comprehensive loss	24	[1]	22	[1]	49	43	[1]
Recognized from regulatory asset	104		92		208	184
Total recognized in net periodic benefit cost	128		114		257	227
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	0		2		0	5
Net loss	22		25		44	50
Recognized from accumulated other comprehensive loss	22	[1]	27	[1]	44	55	[1]
Recognized from regulatory asset	0		0		0	0
Total recognized in net periodic benefit cost	22		27		44	55
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)	(20)		(19)		(40)	(39)
Net loss	17		17		34	35
Recognized from accumulated other comprehensive loss	(3)	[1]	(2)	[1]	(6)	(4)	[1]
Recognized from regulatory asset	0		0		0	0
Total recognized in net periodic benefit cost	(3)		(2)		(6)	(4)
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		2		0	3
Recognized from accumulated other comprehensive loss	0	[1]	0	[1]	0	1	[1]
Recognized from regulatory asset	0		2		0	2
Total recognized in net periodic benefit cost	$ 0		$ 2		$ 0	$ 3

[1] (1) See Note 8, Accumulated Other Comprehensive Loss.