Notes Payable (Details Textual) (USD $)	9 Months Ended	12 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Short-term Debt [Line Items]
Notes Payable Reduction	$ 115,849,000	$ 0	$ 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
Four Percent Convertible Debt [Member]
Short-term Debt [Line Items]
Interest Payable, Current			$ 400,000
Debt Instrument, Interest Rate, Stated Percentage			4.00%

Contractual interest rate for funds borrowed, under the debt agreement.

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Carrying value as of the balance sheet date of [accrued] interest payable on all forms of debt, including trade payables, that has been incurred and is unpaid. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

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Carrying value as of the balance sheet date of notes payable (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

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The cash outflow for a borrowing supported by a written promise to pay an obligation.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

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