Fair Value Measurements

9 Months Ended

Sep. 30, 2011

Fair Value Measurements [Abstract]

Fair Value Measurements

5. Fair Value Measurements

The following table sets forth the financial assets and liabilities that were measured at fair value on a recurring basis at September 30, 2011, by level within the fair value hierarchy. The assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement.

The Company’s short-term and long-term investments have been classified as Level 2, which have been initially valued at the transaction price and subsequently revalued, at the end of each reporting period, utilizing a third party pricing service. The pricing service utilizes industry standard valuation models and observable market inputs to determine value that include surveying the bond dealer community, obtaining benchmark quotes, incorporating relevant trade data, and updating spreads daily.

There have been no transfers of assets or liabilities between the fair value measurement classifications.

			Quoted prices in
			active markets for		Significant other		Significant
			identical assets		observable inputs		unobservable inputs
September 30, 2011	Total		(Level 1)		(Level 2)		(Level 3)
Cash equivalents	$	14,560,266	$	9,994,350	$	4,565,916	$	—
Short-term investments available-for-sale		36,702,869		—		36,702,869		—
Long-term investments available-for-sale		999,870		—		999,870		—
Total	$	52,263,005	$	9,994,350	$	42,268,655	$	—

Cash equivalents primarily consist of money market funds and commercial paper. Short-term investments consist of debt securities of U.S. government agencies, commercial paper and corporate debt notes classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of maturity. Long-term investments consist of debt securities of U.S. government agencies with maturities over 365 days from the date of maturity.

The Company has had no realized gains or losses from the sale of investments for the three months and nine months ended September 30, 2011. The following table shows the unrealized gains and losses and fair values for those investments as of September 30, 2011 and December 31, 2010 aggregated by major security type:

			Unrealized		Unrealized
September 30, 2011	At Cost		Gains		(Losses)			At Fair Value
Short-term
Money market funds	$	9,994,350	$	—	$	—		$	9,994,350
Debt securities of U.S. government agencies		7,250,253		216		(914	)		7,249,555
Commercial paper		14,338,423		14,786		(474	)		14,352,735
Corporate debt		19,712,985		—		(46,490	)		19,666,495
Long-term
Debt securities of U.S. government agencies		1,000,000		—		(130	)		999,870
Total	$	52,296,011	$	15,002	$	(48,008	)	$	52,263,005

			Unrealized		Unrealized
December 31, 2010	At Cost		Gains		(Losses)			At Fair Value
Short-term
Money market funds	$	7,932,606	$	—	$	—		$	7,932,606
Commercial paper		6,494,842		2,713		—			6,497,555
Corporate debt		4,519,363		221		(2,392	)		4,517,192
Total	$	18,946,811	$	2,934	$	(2,392	)	$	18,947,353

As of September 30, 2011, the Company had investments in an unrealized loss position. The Company has determined that the unrealized losses on these investments at September 30, 2011 are temporary in nature and expects the securities to mature at their stated principal. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized costs bases, which may be maturity.