Credit Facilities (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Credit Facilities (Textual) [Abstract]
Maximum borrowing capacity under the bank line of credit facility	$ 10.0
Amounts outstanding under the bank line of credit facility	0	0
Borrowings under the bank line of credit facility	$ 0	$ 0
Line of credit facility financial covenant terms	3.41 to 1
Interest rate	3.25%
Unrestricted Cash Cash Equivalents and Short Term Investments to Current Liabilities Ratio	maintain unrestricted cash, accounts receivable and short-term investments to current liabilities of at least 1.75 to 1.00
Annualized rate of LIBOR	0.28%
Percentage added to LIBOR to facilitate line of credit.	1.75%