Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Fair Value, by Balance Sheet Grouping [Table Text Block]

	Assets and Liabilities at Fair Value
	As of December 31, 2012
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash and cash equivalents	$	30,423	$	—	$	—	$	30,423
Short-term investments	192,785		—		—		192,785
Total cash and cash equivalents and investments	$	223,208	$	—	$	—	$	223,208
Liabilities
Other long-term liabilities	$	—	$	—	$	29,920	$	29,920
Total liabilities	$	—	$	—	$	29,920	$	29,920

	Assets and Liabilities at Fair Value
	As of December 31, 2011
	Level 1		Level 2		Level 3		Total
	(in thousands)
Assets
Cash and cash equivalents	$	186,309	$	—	$	—	$	186,309
Short-term investments	95,383		—		—		95,383
Total cash and cash equivalents and investments	$	281,692	$	—	$	—	$	281,692
Liabilities
Other long-term liabilities	$	—	$	—	$	55,033	$	55,033
Total liabilities	$	—	$	—	$	55,033	$	55,033

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	Short-term Investments
	(in thousands)
Balance at December 31, 2009	$	56,034
Unrealized gains included in earnings as gain on investments, net	141
Net sales and settlements	(56,175		)
Balance at December 31, 2010	$	—

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	Other Long-term Liabilities
	(in thousands)
Balance at December 31, 2009	$	—
Purchase consideration liability resulting from the Symphony Icon acquisition	45,557
Change in valuation of purchase consideration payable to former Symphony Icon stockholders	2,710
Balance at December 31, 2010	48,267
Change in valuation of purchase consideration payable to former Symphony Icon stockholders	6,766
Balance at December 31, 2011	55,033
Change in valuation of purchase consideration payable to former Symphony Icon stockholders	9,887
Payment of base payment obligation with common stock	(35,000		)
Balance at December 31, 2012	$	29,920