Fair Value Measurements (Details Textual) $ in Millions	12 Months Ended
	Mar. 31, 2017 USD ($) $ / MWh
Level 3 Instruments [Member]
Fair Value Measurements [Abstract]
Unrealized losses related to financial instruments | $	$ (5)
Extended Electricity Swaps [Member]
Fair Value Measurements [Abstract]
Average forward price (per megawatt hour)	40
Premium over forward prices in nearby observable market (per megawatt hour)	1
Actual swap settlement price (per megawatt hour)	37
Change in valuation per a dollar per megawatt hour decline in price (less than) | $	$ 1