Commitments and Contingencies (Details) (Natural gas, USD $) | 1 Months Ended | 3 Months Ended | 9 Months Ended |
In Millions, unless otherwise specified | Oct. 31, 2008 | Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 |
| MMBTU |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas per year (in MMBTUs) | 334,000 | ' | ' | ' | ' |
Purchases under the gas contract | ' | $0.50 | $0.50 | $1.40 | $1.50 |
April 2011 - March 2012 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 334,207 | ' |
Price per MMBTU | ' | ' | ' | 6.5 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
April 2012 - March 2013 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 334,207 | ' |
Price per MMBTU | ' | ' | ' | 5.5 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
April 2013 - December 2014 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 556,886 | ' |
Price per MMBTU | ' | ' | ' | 4.905 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
April 2013 - September 2013 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Additional MMBTUs per month | ' | ' | ' | 5,000 | ' |
Price per MMBTU | ' | ' | ' | 4.7 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
October 2013 - March 2014 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Additional MMBTUs per month | ' | ' | ' | 5,000 | ' |
Price per MMBTU | ' | ' | ' | 4.75 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
April 2014 - December 2014 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Additional MMBTUs per month | ' | ' | ' | 5,000 | ' |
Price per MMBTU | ' | ' | ' | 4.7 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
January 2015 - March 2015 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 95,900 | ' |
Price per MMBTU | ' | ' | ' | 4.5 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
April 2015 - June 2015 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 93,600 | ' |
Price per MMBTU | ' | ' | ' | 4.3 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
July 2015 - September 2015 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 92,300 | ' |
Price per MMBTU | ' | ' | ' | 4.35 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
October 2015 - December 2015 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 91,900 | ' |
Price per MMBTU | ' | ' | ' | 4.5 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
January 2016 - March 2016 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 95,900 | ' |
Price per MMBTU | ' | ' | ' | 4.53 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
April 2016 - June 2016 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 93,600 | ' |
Price per MMBTU | ' | ' | ' | 4.17 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
July 2016 - September 2016 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 92,300 | ' |
Price per MMBTU | ' | ' | ' | 4.26 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
October 2016 - December 2016 | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Quantity of natural gas requirements (in MMBTUs) | ' | ' | ' | 91,900 | ' |
Price per MMBTU | ' | ' | ' | 4.42 | ' |
Management fee per MMBTU | ' | ' | ' | 0.07 | ' |
Minimum | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Amount under the contract as a percent of the entity's requirements | ' | ' | ' | 60.00% | ' |
Maximum | ' | ' | ' | ' | ' |
Commitments and Contingencies | ' | ' | ' | ' | ' |
Amount under the contract as a percent of the entity's requirements | ' | ' | ' | 70.00% | ' |