Investments and Fair Value Disclosures (Tables)

6 Months Ended

Jun. 30, 2012

Investments and Fair Value Disclosures [Abstract]

Summary of long-term investments

	June 30, 2012
	Contracted Maturity	Carrying Value
		(in thousands)
Money market funds	demand	$	53,160
Total cash equivalents		$	53,160
U.S. agency notes	30 - 382 days	$	30,708
Commercial paper	9 - 258 days		27,502
Corporate bonds	32 - 349 days		31,358
Total short-term investments		$	89,568
U.S. agency notes	368 - 514 days	$	17,991
Corporate bonds	401 days		2,414
Total long-term investments		$	20,405

Summary of carrying and fair value of the Company's financial assets and liabilities

	June 30, 2012				December 31, 2011
	Carrying Value		Fair Value		Carrying Value		Fair Value
Assets
Cash equivalents and certificates of deposit *	$	54,165	$	54,165	$	71,147	$	71,147
Short and long-term investments		109,973		109,973		97,749		97,749
Total assets	$	164,138	$	164,138	$	168,896	$	168,896
Liabilities
Convertible senior notes **	$	84,048	$	120,000	$	81,737	$	120,000
Notes payable and bank loans		923		923		1,352		1,352
Total liabilities	$	84,971	$	120,923	$	83,089	$	121,352

* Does not include $31.1 million and $23.9 million of operating cash balances as of June 30, 2012 and December 31, 2011, respectively.

** The carrying value represents the bifurcated debt component only, while the fair value is based on the principal amount of the notes, which did not separate the liability and equity components of the debt instrument.

Summary of assets and liabilities measured at fair value on a recurring basis

	June 30, 2012		Level 1		Level 2		Level 3
Money market funds	$	53,160	$	53,160	$	—	$	—
Certificates of deposit		1,005		1,005		—		—
Total cash equivalents and certificates of deposit		54,165		54,165		—		—
U.S. agency notes		48,699		—		48,699		—
Commercial paper		27,502		—		27,502		—
Corporate bonds		33,772		—		33,772		—
Total investments		109,973		—		109,973		—
Total cash equivalents, certificates of deposit and investments	$	164,138	$	54,165	$	109,973	$	—
	December  31, 2011		Level 1		Level 2		Level 3
Money market funds	$	70,142	$	70,142	$	—	$	—
Certificates of deposit		1,005		1,005		—		—
Total cash equivalents and certificates of deposit		71,147		71,147		—		—
U.S. agency notes		27,672		—		27,672		—
Commercial paper		15,735		—		15,735		—
Corporate bonds		54,342		—		54,342		—
Total investments		97,749		—		97,749		—
Total cash equivalents, certificates of deposit and investments	$	168,896	$	71,147	$	97,749	$	—