Credit Facilities (Details) (USD $)	0 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended	13 Months Ended			19 Months Ended	6 Months Ended					1 Months Ended		19 Months Ended	6 Months Ended
	Dec. 31, 2012	Dec. 21, 2011	Mar. 31, 2012	Mar. 31, 2013 letter_of_credit	Dec. 31, 2012	Dec. 21, 2011	Sep. 30, 2012	Nov. 11, 2010	Jun. 14, 2012 July 1, 2012	Dec. 31, 2012 January 1, 2013	Dec. 28, 2012 Before March 31, 2013	Dec. 28, 2012 After March 31, 2013	Mar. 31, 2013 December 31, 2012	Mar. 31, 2013 June 30, 2013	Dec. 31, 2011 Revolving Credit Facility	Mar. 31, 2013 Revolving Credit Facility letter_of_credit	Jun. 14, 2012 Revolving Credit Facility July 1, 2012	Dec. 31, 2012 Revolving Credit Facility January 1, 2013	Mar. 31, 2013 Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, term (in years)								3 years
Line of credit facility, maximum borrowing capacity								$ 35,000,000			$ 7,600,000	$ 5,000,000				$ 35,000,000
Line of credit facility, monthly reduction amount											101,000	91,000
Line of credit facility, covenant terms	3,500,000	7,500,000			3,500,000	7,500,000
Excess availability financial covenant requirement, revised amount															3,500,000
Increase in eligible borrowing base			10,000,000												10,000,000
Line of credit facility, borrowing base formula adjustment, percentage of appraised value of equipment			85.00%
Line of credit facility borrowing base formula adjustment addition to borrowing base			50.00%
Debt instrument, basis spread on variable rate																			4.00%
Credit facility amendment condition, upon receipt of flood-related insurance proceeds in excess of this amount				30,000,000											30,000,000
Line of credit facility, automatic borrowing base reduction, first amendment									8,100,000	3,100,000							8,100,000	3,100,000
Line of credit facility, automatic borrowing base reduction, second amendment									5,000,000	0							5,000,000	0
Borrowings from credit facility				20,779,000			19,316,000
Credit facility, interest rate on outstanding balance																3.40%
Standby letters of credit, total amount outstanding				2,400,000
Number of standby letters of credit outstanding				6												6
Line of credit facility, expected amount of credit to be available under credit facility, percent of total amount credit				70.00%
Line of credit facility, minimum cash balance and excess liquidity requirement				3,500,000
Line of credit facility, increase in minimum cash balance and excess liquidity requirement													$ 7,500,000	$ 1,000,000