ABL Credit Facility (Details) (USD $)							0 Months Ended
	Jul. 31, 2014 Letter of Credit	Jul. 31, 2014 Revolving Credit Facility	Jul. 15, 2014 Revolving Credit Facility	Jul. 14, 2014 Revolving Credit Facility	Jul. 31, 2014 4.0% Convertible Senior Notes due March 15, 2015	Jul. 15, 2014 4.0% Convertible Senior Notes due March 15, 2015 Convertible Notes Payable	Jul. 15, 2014 London Interbank Offered Rate (LIBOR) Revolving Credit Facility Minimum	Jul. 14, 2014 London Interbank Offered Rate (LIBOR) Revolving Credit Facility Minimum	Jul. 15, 2014 London Interbank Offered Rate (LIBOR) Revolving Credit Facility Maximum	Jul. 14, 2014 London Interbank Offered Rate (LIBOR) Revolving Credit Facility Maximum
Line of Credit Facility [Line Items]
Total commitment			$ 200,000,000	$ 150,000,000
Interest rate on convertible notes					4.00%	4.00%
Required minimum aggregate amount of unrestricted cash and cash equivalents			150,000,000	200,000,000
Borrowing base eligible cash			50,000,000
Letters of credit collateralized by the credit facility	56,000,000
Borrowings outstanding		$ 0
Interest basis spread on LIBOR							1.50%	2.00%	2.00%	2.50%