Subsequent Events Subsequent Events (Details) (USD $)	3 Months Ended			0 Months Ended	1 Months Ended			0 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Jan. 25, 2013 Convertible Senior Subordinated Notes	Jan. 24, 2013 Convertible Senior Subordinated Notes	Mar. 31, 2014 Convertible Senior Subordinated Notes	Jan. 24, 2013 Early Conversion Payment Convertible Senior Subordinated Notes	Apr. 02, 2014 Subsequent Event	Oct. 02, 2014 Subsequent Event Convertible Senior Subordinated Notes	Apr. 02, 2014 Subsequent Event Convertible Senior Subordinated Notes	Apr. 02, 2014 Subsequent Event Early Conversion Payment Convertible Senior Subordinated Notes
Subsequent Event [Line Items]
Aggregate principal amount of debt					$ 125,000,000					$ 149,500,000
Debt instrument, fixed interest rate					6.00%					5.00%
Interest payment, beginning date				Aug. 01, 2013					Oct. 01, 2014
Net proceeds from Note offering	0	119,750,000			119,200,000					143,500,000
Conversion rate					121.1240					75.7576
Principal amount of convertible notes, denominator					1,000	1,000	1,000			1,000	1,000
Conversion price of per share					$ 8.26					$ 13.20
Conversion Of Stock Conversion Price							$ 83.33				$ 83.33
Common stock, shares issued	70,203,216		68,744,534					5,750,000
Common stock, par value	$ 0.001		$ 0.001					$ 0.001
Share Price								$ 11.00
Proceeds from the issuance of common stock, net of repurchases	$ 4,914,000	$ 260,000						$ 59,300,000