Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Document Period End Date			Sep. 30, 2015
Expected pension and postretirement benefit costs			$ 1,200
Expected amortization of pre merger regulatory asset			769
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	$ 17	$ 17	50	$ 50
Contribution to pension plan	47		163
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			207
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	9	10	28	31
Contribution to pension plan	14		42
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			79
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	50	40	150	119
Contribution to pension plan	38		109
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			151
Consolidated [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost			(381)
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	58	11	173	34
Contribution to pension plan	127		346
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			475
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Unamortized balance of regulatory asset	3,100		3,100		$ 3,600
Defined Benefit Plan, Net Periodic Benefit Cost	(37)	$ (126)	(112)	$ (377)
Contribution to pension plan	$ 402		1,100
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year			$ 1,600