Fair Value Measurement

The valuation hierarchy for disclosure of assets and liabilities reported at fair value prioritizes the inputs for such valuations into three broad levels:


•	Level 1: quoted prices (unadjusted) in active markets for identical assets or liabilities;


•	Level 2: quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument; or


•	Level 3: unobservable inputs based on the Company's own assumptions used to measure assets and liabilities at fair value.

A financial asset's or liability's classification within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement.

The following tables provide the assets and liabilities carried at fair value and measured on a recurring basis:



			Fair Value Measurements at Reporting Date Using:
(in thousands)	March 31, 2016		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Cash equivalents	$	342,402	$	342,402	$	—	$	—
Short-term investments	$	442	$	—	$	442	$	—



				Fair Value Measurements at Reporting Date Using:
(in thousands)	December 31, 2015			Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Cash equivalents	$	356,924		$	356,924	$	—	$	—
Short-term investments	$	446		$	—	$	446	$	—
Liabilities
Contingent consideration	$	(1,376	)	$	—	$	—	$	(1,376	)

The cash equivalents in the preceding tables represent money market mutual funds.

The short-term investments in the preceding tables represent deposits held by certain foreign subsidiaries of the Company. The deposits have fixed interest rates with maturity dates ranging from three months to one year.

The contingent consideration in the table above represents the final payment related to the 2013 acquisition of EVEN - Evolutionary Engineering AG ("EVEN"). The net present value calculation for the contingent consideration, which was paid during the quarter ended March 31, 2016, included significant unobservable inputs as of December 31, 2015 in the assumption that the remaining payment would be made, and, therefore, the liability was classified as Level 3 in the fair value hierarchy.

The following tables present the changes in the Company’s Level 3 liabilities that are measured at fair value on a recurring basis during the three months ended March 31, 2016 and 2015:



	Fair Value Measurement Using Significant Unobservable Inputs
(in thousands)	Contingent Consideration
Balance as of January 1, 2016	$	1,376
Contingent payment	(1,448		)
Interest expense and foreign exchange activity included in earnings	72
Balance as of March 31, 2016	$	—



	Fair Value Measurement Using Significant Unobservable Inputs
(in thousands)	Contingent Consideration
Balance as of January 1, 2015	$	2,621
Interest expense and foreign exchange activity included in earnings	122
Balance as of March 31, 2015	$	2,743

The carrying values of cash, accounts receivable, accounts payable, accrued expenses, other accrued liabilities and short-term obligations approximate their fair values because of their short-term nature.