Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2011

Fair Value Measurements

Schedule of fair value of assets and liabilities measured on a recurring basis

			Fair Value Measurements at Reporting Date Using
	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Money Market Funds(1)	$	40,197	$	40,197	$	—	$	—
US government debt securities(2)		11,323		11,323		—		—
Corporate debt securities(3)		52,605		—		52,605		—
Foreign government debt securities(4)		8,432		—		8,432		—
Total	$	112,557	$	51,520	$	61,037	$	—

(1)

Included in cash and cash equivalents on the Company's consoldiated balance sheet.

(2)

Included in short-term and long-term marketable securities on the Company's consolidated balance sheet.

(3)

Included in short-term marketable securities on the Company's consolidated balance sheet.

(4)

Included in cash and cash equivalents, and short-term marketable securities on the Company's consolidated balance sheet.