Employee Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost	$ (20)	$ (17)	$ (40)	$ (34)
Amortization of net loss	270	249	541	496
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	105	102	210	204
Expected return on plan assets	(131)	(135)	(261)	(270)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	103	91	206	181
Net periodic cost (benefit)	77	58	155	115
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	77	58	155	115
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	630	626	1,259	1,251
Expected return on plan assets	(701)	(777)	(1,402)	(1,554)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	128	114	257	227
Net periodic cost (benefit)	57	(37)	114	(76)
Amortization of pre-merger regulatory asset	191	191	381	381
Total periodic cost	248	154	495	305
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	0	2	0	5
Amortization of net loss	22	25	44	50
Net periodic cost (benefit)	45	50	90	101
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	45	50	90	101
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	11	11	21	22
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(20)	(19)	(40)	(39)
Amortization of net loss	17	17	34	35
Net periodic cost (benefit)	8	9	15	18
Amortization of pre-merger regulatory asset	0	0	0	0
Total periodic cost	8	9	15	18
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	14	15	28	30
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	0	0	0
Amortization of net loss	0	2	0	3
Net periodic cost (benefit)	14	17	28	33
Amortization of pre-merger regulatory asset	2	2	4	4
Total periodic cost	$ 16	$ 19	$ 32	$ 37