Debt Security Investments

3 Months Ended

Mar. 31, 2012

Debt Security Investments [Abstract]

Debt Security Investments

3. Debt Security Investments

The Company's debt security investments are held in United States Treasury securities. The Company has classified these investments as held-to-maturity as the Company has the intent and ability to hold these securities to maturity. Investments with original maturities of greater than 90 days and current maturities of one year or less are recorded as short-term. Investments with current maturities of greater than one year are recorded as long-term. The securities are carried at amortized cost, and interest income is recorded using an effective interest rate with the associated discount or premium amortized to interest income, which is reported in "Other income, net" in the unaudited condensed consolidated statement of operations.

The following table summarizes amortized cost, gross unrealized gains, gross unrealized losses and fair values of debt security investments (in thousands):

	March 31, 2012									December 31, 2011
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
U.S. Treasury securities	$	83,506	$	—	$	(62	)	$	83,444	$	33,481	$	—	$	(2	)	$	33,479

The following table presents the amortized cost and fair value of debt security investments, by contractual maturity (in thousands):

	March 31, 2012
	Amortized Cost		Fair Value
Due in one year or less	$	47,641	$	47,613
Due after one year through five years		35,865		35,831
Total securities held to maturity	$	83,506	$	83,444

Fair value for debt security investments are estimated using best available evidence including broker quotes, prices for similar investments, interest rates and credit risk. Debt security investments are reviewed periodically to determine if a permanent decline in fair value has occurred that would require impairment of the carrying value. No impairments on the debt security investments have been recorded.