Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Expected pension and postretirement benefit costs	$ 1,600
Expected amortization of pre merger regulatory asset	769
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Unamortized balance of regulatory asset	1,900		$ 2,100
Defined Benefit Plan, Net Periodic Benefit Cost	55	$ 57
Contribution to pension plan	374
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	3,000
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	83	78
Contribution to pension plan	48
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	746
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	44	45
Contribution to pension plan	38
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	151
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	7	9
Contribution to pension plan	49
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	83
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost	13	$ 14
Contribution to pension plan	26
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year	$ 129