Convertible Notes - Debt Instruments (Details) (USD $)	12 Months Ended			3 Months Ended	12 Months Ended				12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Convertible Subordinated Debt [Member]	Dec. 31, 2013 Convertible Subordinated Debt [Member]	Dec. 31, 2012 Convertible Subordinated Debt [Member]	Dec. 31, 2011 Convertible Subordinated Debt [Member]	Dec. 31, 2013 Convertible Subordinated Debt [Member]	Dec. 31, 2013 Converted Into Cash [Member]
Debt Instrument [Line Items]
Convertible notes, issuance date					May 19, 2006
Convertible notes, face amount at issuance					$ 115,000,000
Convertible notes, stated interest rate								2.875%
Convertible notes, maturity date					Jun. 01, 2013
Convertible notes, issuance costs at time of issuance					3,100,000
Convertible notes, amortization of issuance costs				100,000
Convertible notes, amount						1,000	1,000
Shares issued during period for debt conversion	3,000,000					34	34
Convertible notes, amount converted	89,000,000								100,000
Convertible notes, noncash amount converted	$ 88,937,000	$ 0	$ 0