Employee Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service cost	$ (19)	$ (20)
Amortization of net loss	276	272
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	103	105
Expected return on plan assets	(127)	(131)
Amortization of prior service cost	0	0
Amortization of net loss	107	104
Net periodic cost (benefit)	83	78
Amortization of pre-merger regulatory asset	0	0
Total periodic cost	83	78
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	623	630
Expected return on plan assets	(699)	(701)
Amortization of prior service cost	0	0
Amortization of net loss	131	128
Net periodic cost (benefit)	55	57
Amortization of pre-merger regulatory asset	191	191
Total periodic cost	246	248
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	22	23
Expected return on plan assets	0	0
Amortization of prior service cost	0	0
Amortization of net loss	22	22
Net periodic cost (benefit)	44	45
Amortization of pre-merger regulatory asset	0	0
Total periodic cost	44	45
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	10	11
Expected return on plan assets	0	0
Amortization of prior service cost	(19)	(20)
Amortization of net loss	16	18
Net periodic cost (benefit)	7	9
Amortization of pre-merger regulatory asset	0	0
Total periodic cost	7	9
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	13	14
Expected return on plan assets	0	0
Amortization of prior service cost	0	0
Amortization of net loss	0	0
Net periodic cost (benefit)	13	14
Amortization of pre-merger regulatory asset	2	2
Total periodic cost	$ 15	$ 16