Financial Derivative Instruments - Fuel Hedging (Details) gal in Millions	Sep. 30, 2015 gal
Fourth quarter 2015
Volume of Fuel Hedging [Line Items]
Fuel Hedged (in gallons)	0	[1]
2016
Volume of Fuel Hedging [Line Items]
Fuel Hedged (in gallons)	1,188	[2]
2017
Volume of Fuel Hedging [Line Items]
Fuel Hedged (in gallons)	1,294	[2]
2018
Volume of Fuel Hedging [Line Items]
Fuel Hedged (in gallons)	466	[2]

[1] The Company is effectively unhedged for fourth quarter 2015 at current price levels. While the Company still holds derivative contracts as of September 30, 2015, that will settle during fourth quarter 2015, the losses associated with those contracts are substantially locked in. However, if market prices were to increase or decrease significantly related to the fourth quarter 2015 positions prior to these contracts settling, the losses incurred at settlement could be slightly lower or higher than currently expected amounts during that period.

[2] Due to the types of derivatives and commodities utilized by the Company and different price levels of those contracts, this volume represents the maximum "economic" net hedge in place. The Company's average "economic" net hedge of estimated fuel consumption covered by fuel derivative contracts is lower than this maximum volume, may vary significantly as market prices fluctuate, and begins to provide hedge coverage at price levels above current market prices.