We define fair value to be the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, we consider the principal or most liquid market and assumptions that market participants would use when pricing the asset or liability.

We follow a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The level in the fair value hierarchy within which the fair value measurement falls is determined based on the lowest level input that is significant to the fair value measurement. The three values of the fair value hierarchy are the following:

Level 1 – Quoted prices in active markets for identical assets or liabilities

Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly

Assets and liabilities measured at fair value on a recurring basis are summarized below (in thousands):


	Fair Value Measurements at Reporting Date Using (Unaudited)
Description	September 30, 2011	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	$ 99,666	$ 99,666	$ 0	$ 0
Short-term investments available for sale:
Municipal bonds	15,441	0	15,441	0
Corporate bonds	77,181	0	77,181	0
U.S. treasuries and agencies...	11,019	0	11,019	0
Foreign government bonds	32,980	0	32,980	0
Time deposits	2,751	0	2,751	0
Derivatives	3,254	0	3,254	0
Total Assets	$ 242,292	$ 99,666	$ 142,626	$ 0

Liabilities
Derivatives	$ (3,115)	$ 0	$ (3,115)	$ 0
Total Liabilities	$ (3,115)	$ 0	$ (3,115)	$ 0


	Fair Value Measurements at Reporting Date Using
Description	December 31, 2010	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	$ 133,103	$ 133,103	$ 0	$ 0
Short-term investments available for sale:
Municipal bonds	16,861	0	16,861	0
Corporate bonds	56,110	0	56,110	0
U.S. treasuries and agencies...	23,135	0	23,135	0
Foreign government bonds	32,657	0	32,657	0
Time deposits	2,452	0	2,452	0
Derivatives	2,325	0	2,325	0
Total Assets	$ 266,643	$ 133,103	$ 133,540	$ 0

Liabilities
Derivatives	$ (3,733)	$ 0	$ (3,733)	$ 0
Total Liabilities	$ (3,733)	$ 0	$ (3,733)	$ 0

We value our available-for-sale short term investments based on pricing from third party pricing vendors, who may use quoted prices in active markets for identical assets (Level 1 inputs) or inputs other than quoted prices that are observable either directly or indirectly (Level 2 inputs) in determining fair value. We classify all of our fixed income available-for-sale securities as having Level 2 inputs. The valuation techniques used to measure the fair value of our financial instruments having Level 2 inputs were derived from non-binding market consensus prices that are corroborated by observable market data, quoted market prices for similar instruments, or pricing models, such as discounted cash flow techniques. Short-term investments available-for-sale consists of debt securities issued by states of the U.S. and political subdivisions of the U.S., corporate debt securities and debt securities issued by U.S. government corporations and agencies as well as debt securities issued by foreign governments. All short-term investments available-for-sale have contractual maturities of less than 24 months.

Derivatives include foreign currency forward and option contracts. Our foreign currency forward contracts are valued using an income approach (Level 2) based on the spot rate less the contract rate multiplied by the notional amount. Our foreign currency option contracts are valued using a market approach based on the quoted market prices which are derived from observable inputs including current and future spot rates, interest rate spreads as well as quoted market prices of similar instruments. There were not any transfers in or out of Level 1 or Level 2 during the three and nine month periods ended September 30, 2011.

Certain investments have been reclassified to conform to current year presentation.

We did not have any items that were measured at fair value on a nonrecurring basis at September 30, 2011 and December 31, 2010.