Debt (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Interest expense on convertible debt instruments
Interest expense at coupon rate (6.0%)	$ 1,378	$ 1,462	$ 2,756	$ 2,925
Non-cash interest in accordance with ASC 470	2,725	2,322	5,450	4,645
Total interest expense recognized on convertible debt instruments	$ 4,103	$ 3,784	$ 8,206	$ 7,570