Convertible Notes (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2012 Notes Due 2013 [Member]	Jun. 30, 2012 Notes Due 2013 [Member]	Jul. 02, 2011 Notes Due 2011 and 2013 [Member]	Jul. 02, 2011 Notes Due 2011 and 2013 [Member]
Effective interest rate and components of interest expense
Effective interest rate	6.40%	6.40%	6.30%	6.30%
Contractual interest expense	$ 540	$ 1,080	$ 1,053	$ 2,106
Amortization of debt discount	$ 1,547	$ 3,086	$ 3,212	$ 6,409