Regulatory Matters (Details) - USD ($)			12 Months Ended
	Mar. 13, 2017	Oct. 11, 2016	Dec. 31, 2016
Distribution Modernization Rider		$ 145,000,000
Distribution Modernization Rider Period		7 years
Regulatory Assets, Renewable Energy Recovery		$ 10,500,000
Energy Reduction Riders		0
Non-bypassable DMR	$ 105,000,000
Service stability rider per year			$ 110,000,000
Subsidiaries [Member]
Distribution Modernization Rider		$ 145,000,000
Distribution Modernization Rider Period		7 years
Regulatory Assets, Renewable Energy Recovery		$ 10,500,000
Energy Reduction Riders		$ 0
Non-bypassable DMR	$ 105,000,000
Service stability rider per year			$ 110,000,000