Employee Benefit Plans - Employee Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Document Period End Date			Jun. 30, 2015
Amortization of prior service cost	$ (17)	$ (15)	$ (34)	$ (30)
Amortization of net loss	249	67	496	132
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	15	16	30	33
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Amortization of net loss	2	0	3	0
Net periodic cost (benefit)	17	16	33	33
Amortization of pre-merger regulatory asset	2	2	4	4
Total periodic cost	19	18	37	37
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	11	13	22	26
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(19)	(20)	(39)	(39)
Amortization of net loss	17	17	35	33
Net periodic cost (benefit)	9	10	18	20
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	9	10	18	20
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	23	23	46	46
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	2	5	5	9
Amortization of net loss	25	12	50	24
Net periodic cost (benefit)	50	40	101	79
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	50	40	101	79
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	626	647	1,251	1,294
Expected return on plan assets	(777)	(772)	(1,554)	(1,545)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	114	0	227	0
Net periodic cost (benefit)	(37)	(125)	(76)	(251)
Amortization of pre-merger regulatory asset	191	191	381	381
Total periodic cost	154	66	305	130
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	102	106	204	213
Expected return on plan assets	(135)	(132)	(270)	(265)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	91	38	181	75
Net periodic cost (benefit)	58	12	115	23
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	$ 58	$ 12	$ 115	$ 23