Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Apr. 01, 2015	Dec. 02, 2013	Feb. 05, 2013	Aug. 30, 2010	Oct. 31, 2009
Goodwill [Line Items]
Goodwill		$ 14,548,000	$ 4,952,000
Amortization of intangible assets		367,000	396,000	$ 373,000
Amortization of intangible assets, 2014		355,000
Amortization of intangible assets, 2015		351,000
Amortization of intangible assets, 2016		353,000
Amortization of intangible assets, 2017		353,000
Amortization of intangible assets, 2018		353,000
Regulated Energy
Goodwill [Line Items]
Goodwill		3,353,000	3,354,000
Unregulated Energy
Goodwill [Line Items]
Goodwill		11,195,000	1,598,000
Goodwill, Impairment Loss	$ 237,000		$ 237,000
FPU | Regulated Energy
Goodwill [Line Items]
Goodwill									$ 2,500,000
Indiantown Gas Company | Regulated Energy
Goodwill [Line Items]
Goodwill								$ 170,000
Fort Meade
Goodwill [Line Items]
Goodwill						$ 714,000
Gatherco [Member]
Goodwill [Line Items]
Goodwill		9,596,000			$ 11,100,000
Gatherco [Member] | Unregulated Energy
Goodwill [Line Items]
Goodwill					$ 9,600,000
Crescent Propane Inc | Unregulated Energy
Goodwill [Line Items]
Goodwill		200,000
Sharp Energy Inc | Unregulated Energy
Goodwill [Line Items]
Goodwill		$ 674,000
Anderson Gas [Member]
Goodwill [Line Items]
Amortized period of acquired intangible assets		6 years
Glades | Unregulated Energy
Goodwill [Line Items]
Goodwill							$ 724,000
Virginia LP Gas, Inc.
Goodwill [Line Items]
Amortized period of acquired intangible assets		7 years
Virginia LP Gas, Inc. | Maximum
Goodwill [Line Items]
Amortized period of acquired intangible assets		40 years
Customer list | Minimum
Goodwill [Line Items]
Amortized period of acquired intangible assets		7 years
Customer list | Maximum
Goodwill [Line Items]
Amortized period of acquired intangible assets		12 years
Non-Compete Agreements
Goodwill [Line Items]
Impairment of Intangible Assets (Excluding Goodwill)		$ 175,000