Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Level 1
Fair Value
Cash and Cash Equivalents	$ 19,581	$ 30,423
Short-term Investments	131,078	192,234
Total Cash and Cash Equivalents and Investments	150,659	222,657
Other Long-term Liabilities	0	0
Total Liabilities	0	0
Fair Value, Level 2
Fair Value
Cash and Cash Equivalents	0	0
Short-term Investments	551	551
Total Cash and Cash Equivalents and Investments	551	551
Other Long-term Liabilities	0	0
Total Liabilities	0	0
Fair Value, Level 3
Fair Value
Cash and Cash Equivalents	0	0
Short-term Investments	0	0
Total Cash and Cash Equivalents and Investments	0	0
Other Long-term Liabilities	32,999	29,920
Total Liabilities	32,999	29,920
Fair Value, Total
Fair Value
Cash and Cash Equivalents	19,581	30,423
Short-term Investments	131,629	192,785
Total Cash and Cash Equivalents and Investments	151,210	223,208
Other Long-term Liabilities	32,999	29,920
Total Liabilities	$ 32,999	$ 29,920