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		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		$ (17)	$ (14)	$ (50)	$ (44)
Net loss		249	65	745	198
Recognized from accumulated other comprehensive loss	[1]	138	51	415	154
Recognized from regulatory asset		94	0	280	0
Total recognized in net periodic benefit cost		232	51	695	154
Chesapeake Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	0	0	0
Net loss		91	37	272	112
Recognized from accumulated other comprehensive loss	[1]	91	37	272	112
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		91	37	272	112
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		114	0	341	0
Recognized from accumulated other comprehensive loss	[1]	22	0	65	0
Recognized from regulatory asset		92	0	276	0
Total recognized in net periodic benefit cost		114	0	341	0
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		2	5	8	14
Net loss		25	12	74	36
Recognized from accumulated other comprehensive loss	[1]	27	17	82	50
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		27	17	82	50
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		(19)	(19)	(58)	(58)
Net loss		17	16	53	50
Recognized from accumulated other comprehensive loss	[1]	(2)	(3)	(5)	(8)
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		(2)	(3)	(5)	(8)
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		2	0	5	0
Recognized from accumulated other comprehensive loss	[1]	0	0	1	0
Recognized from regulatory asset		2	0	4	0
Total recognized in net periodic benefit cost		$ 2	$ 0	$ 5	$ 0

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