Investments in Marketable Securities

12 Months Ended

Dec. 31, 2011

Investments, Debt and Equity Securities [Abstract]

Investments in Cash Equivalents and Marketable Securities

Investments in Marketable Securities

As of December 31, 2011 all short-term investments are classified as available-for-sale and have maturity dates of less than one year. All unrealized gains and losses on available-for-sale investments are included in other comprehensive income. The cost, gross unrealized holding gains, gross unrealized holding losses and fair value of available-for-sale investments by types and classes of security at December 31, 2011 consisted of the following:

At December 31, 2011	Cost		Net unrealized holding gains		Net unrealized holding losses			Fair Value
Available-for-sale - included in cash equivalents:
Corporate debt securities	$	24,010	$	—	$	—		$	24,010
Money market funds and other	40,793		—		—			40,793
U.S. government-sponsored enterprise securities	4,000		—		—			4,000
Available-for-sale - included in short-term marketable securities:
Municipal notes	9,295		—		—			9,295
U.S. treasury securities	7,501		—		—			7,501
U.S. government-sponsored enterprise securities	16,506		—		(1		)	16,505
Corporate debt securities	12,704		1		—			12,705
	$	114,809	$	1	$	(1	)	$	114,809

The cost, gross unrealized holding gains, gross unrealized holding losses and fair value of available-for-sale investments by types and classes of security at December 31, 2010 consisted of the following:

At December 31, 2010	Cost		Net unrealized holding gains		Net unrealized holding losses			Fair Value
Available-for-sale - included in cash equivalents:
U.S. treasury securities	$	5,500	$	—	$	—		$	5,500
Certificates of deposit	325		—		—			325
Money market funds and other	114,217		—		—			114,217
Available-for-sale - included in short-term marketable securities:
U.S. treasury securities	3,115		—		(2		)	3,113
U.S. government-sponsored enterprise securities	26,366		4		—			26,370
Certificates of deposit	1,709		—		—			1,709
	$	151,232	$	4	$	(2	)	$	151,234

The contractual maturities of investments as of December 31, 2011 and 2010 were all due or callable in one year or less.

Investments are considered to be impaired when a decline in fair value is judged to be other-than-temporary. The Company employs a methodology that reviews specific securities in evaluating potential impairment of its investments. In the event that the cost of an investment exceeds its fair value, the Company evaluates, among other factors, the Company’s intent and ability to hold the investment and extent to which the fair value is less than cost; the financial health of and business outlook for the issuer; and operational and financing cash flow factors. At December 31, 2011, all unrealized holding losses were considered to be temporary since the Company has the ability and intent to hold the investments until a recovery of fair value. During 2011, 2010 and 2009, the Company did not record any other-than-temporary impairments on its marketable securities.