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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		$ (20)	$ (17)	$ (60)	$ (50)
Net loss		274	249	815	745
Recognized from accumulated other comprehensive loss	[1]	146	138	440	415
Recognized from regulatory asset		108	94	315	280
Total recognized in net periodic benefit cost		254	232	755	695
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	309	272
Recognized from accumulated other comprehensive loss	[1]	103	91	309	272
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		103	91	309	272
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		133	114	389	341
Recognized from accumulated other comprehensive loss	[1]	25	22	74	65
Recognized from regulatory asset		108	92	315	276
Total recognized in net periodic benefit cost		133	114	389	341
Chesapeake Pension SERP [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		0	2	0	8
Net loss		22	25	66	74
Recognized from accumulated other comprehensive loss	[1]	22	27	66	82
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		22	27	66	82
Chesapeake Postretirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Prior service cost (credit)		(20)	(19)	(60)	(58)
Net loss		16	17	51	53
Recognized from accumulated other comprehensive loss	[1]	(4)	(2)	(9)	(5)
Recognized from regulatory asset		0	0	0	0
Total recognized in net periodic benefit cost		(4)	(2)	(9)	(5)
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	5
Recognized from accumulated other comprehensive loss	[1]	0	0	0	1
Recognized from regulatory asset		0	2	0	4
Total recognized in net periodic benefit cost		$ 0	$ 2	$ 0	$ 5

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