Other Assets - Additional Information (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Dec. 10, 2014
Other Assets [Line Items]
Deferred costs recoverable in future years	$ 23,793,000	$ 23,793,000
Sharyland Distribution & Transmission Services
Other Assets [Line Items]
Credit facility, maximum borrowing capacity	196,000,000
Revolving Credit Facility | Sharyland Distribution & Transmission Services
Other Assets [Line Items]
Credit facility, maximum borrowing capacity			$ 250,000,000
Senior Secured Notes, 8.50%
Other Assets [Line Items]
Long-term debt, face amount	$ 25,000,000
Long-term debt, stated interest rate	8.50%	8.50%
Senior Notes | Senior Secured Notes, 8.50%
Other Assets [Line Items]
Long-term debt, stated interest rate	8.50%