Convertible Subordinated Notes (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2011
Convertible Subordinated Notes (Textual) [Abstract]
Notes conversion rate	46.4727
Principal amount of convertible Note	$ 1,000
Conversion Price	$ 21.52
Debt instrument convertible terms of redemption	We may redeem the Notes in whole or in part for cash at a redemption price equal to 100% of the principal amount of the Notes plus any accrued but unpaid interest if the closing price of the common stock has exceeded 150% of the conversion price for at least 20 days in any consecutive 30 day trading period.
Percentage of principal amount	100.00%
Percentage of conversion price	150.00%
Closing price of common stock exceeding conversion price period	20 days
Consecutive trading period	30 days
3.25% Notes due September 2012 [Member]
Debt Instrument [Line Items]
Percentage interest rate of convertible subordinated notes due	3.25%