Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2013

Fair Value Disclosures [Abstract]

Summary of fair value for assets measured on recurring basis

The following tables summarize our fair value hierarchy for assets and liabilities measured at fair value on a recurring basis (in thousands):

	Fair Value Measurements at Reporting Date Using
Description	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
As of September 30, 2013
Cash equivalents:
Money market funds	$	8,144	$	8,144	$	—
U.S. treasury securities	5,204		5,204		—
Total cash equivalents	13,348		13,348		—
Marketable securities:
U.S. treasury securities	35,005		35,005		—
Certificates of deposit	10,490		—		10,490
Mutual funds	466		466		—
Total marketable securities	45,961		35,471		10,490
Total	$	59,309	$	48,819	$	10,490

	Fair Value Measurements at Reporting Date Using
Description	Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)
As of December 31, 2012
Cash equivalents:
Money market funds	$	105,141	$	105,141	$	—
Certificates of deposit	1,391		—		1,391
Total cash equivalents	106,532		105,141		1,391
Marketable securities:
U.S. treasury securities	40,015		40,015		—
Certificates of deposit	11,738		—		11,738
Mutual funds	387		387		—
Total marketable securities	52,140		40,402		11,738
Total	$	158,672	$	145,543	$	13,129

Fair Value Measurements, Nonrecurring

The following table summarizes our assets and liabilities measured at fair value on a nonrecurring basis during the three and nine months ended September 30, 2013, the respective input levels based on the fair value hierarchy contained in fair value measurements and disclosures accounting guidance and the effect of the measurements on the statement of operations (in thousands):

	Fair Value Measurements at
	September 30, 2013
	using:
			Quoted Prices in
			Active Markets		Significant		Losses for the
			for Identical		Unobservable		Nine Months Ended
Description	Fair Value		Liabilities (Level 1)		Inputs (Level 3)		September 30, 2013
Facility Exit Liabilities	$	2,427	$	504	$	1,923	$	2,414
Leasehold improvements	—		—		—		1,733
Other assets	—		—		—		650

Carrying amounts and fair value of long-term obligations

The carrying amounts and fair values of our Convertible Senior Notes are as follows (in thousands):

	September 30, 2013				December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Convertible Senior Notes	$	130,000	$	124,963	$	130,000	$	156,000