Employee Benefit Plans - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Expected pension and postretirement benefit costs	$ 1,310
Expected amortization of pre merger regulatory asset	543
Florida Public Utilities Company Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Unamortized balance of regulatory asset	351
Contribution to pension plan	233
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	1,200
Chesapeake Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan	33
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	163
Chesapeake Pension SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan	38
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	383
Chesapeake Postretirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan	1
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	96
Florida Public Utilities Company Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contribution to pension plan	6
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	$ 94