Long-Term Debt - Summary of long term debt (Details) (Parenthetical) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Industrial Development Revenue Bonds; secured by an equivalent letter of credit from a bank with interest payable monthly at a floating rate (0.31% at June 30, 2013) (A) | Letter of credit from bank
Debt Instrument [Line Items]
Percentage of floating interest rate payable	0.31%
Secured term loan payable to a government agency; monthly payments of $1,950 including interest fixed at 3% payable through fourth quarter of 2015
Debt Instrument [Line Items]
Percentage of fixed interest rate payable	3.00%
Monthly principal payments	$ 1,950
Frequency of principal payments	Monthly