Notes Payable (Details Textual) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Short-term Debt [Line Items]
Notes Payable Reduction			$ 13,600,000
Write off of Deferred Debt Issuance Cost			62,000
Unamortized Debt Issuance Expense			200,000
Debt Instrument, Interest Rate, Stated Percentage	4.00%		4.00%
Notes payable			115,800,000
Proceeds from (Repayments of) Notes Payable	(115,849,000)	0
Four Percent Convertible Debt [Member]
Short-term Debt [Line Items]
Interest Payable, Current			$ 400,000
Debt Instrument, Interest Rate, Stated Percentage			4.00%