Marketable Securities

12 Months Ended

Dec. 31, 2013

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

3.    Marketable Securities

Marketable securities consist of certificates of deposit, corporate notes, commercial paper, U.S. government treasury securities and securities of government-sponsored entities. The Company classifies all securities as available-for-sale, as the sale of such securities may be required prior to maturity to implement management strategies. These securities are carried at fair value, with the unrealized gains and losses reported as a component of other comprehensive income (loss) in stockholder’s equity until realized. A decline in the market value of any marketable security below cost that is determined to be other-than-temporary will result in a revaluation of its carrying amount to fair value. The impairment is charged to earnings and a new cost basis for the security is established. No such impairment charges were recorded for any period presented.

Realized gains and losses from the sale of marketable securities, if any, are determined on a specific identification basis. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income or expense on the consolidated statements of operations. Realized gains and losses during the periods presented were immaterial. Premiums and discounts are amortized or accreted over the life of the related security as an adjustment to yield using the straight-line method and are included in interest income on the consolidated statements of operations. Interest and dividends on securities classified as available-for-sale are included in interest income on the consolidated statements of operations.

The composition of marketable securities is as follows (in thousands, except years):

	Contractual Maturity (in Years)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
December 31, 2013:
Classified as current assets
Certificates of deposit	Less than 1	$	833	$	—	$	—		$	833
Corporate notes	Less than 1	71,611		23		(6		)	71,628
Commercial paper	Less than 1	19,973		—		—			19,973
U.S. government treasury securities	Less than 1	7,603		2		—			7,605
Securities of government-sponsored entities	Less than 1	43,405		14		(9		)	43,410
Short-term marketable securities		143,425		39		(15		)	143,449
Classified as non-current assets
Certificates of deposit	1 to 2	283		—		—			283
Corporate notes	1 to 2	32,309		23		(14		)	32,318
U.S. government treasury securities	1 to 2	1,500		1		—			1,501
Securities of government-sponsored entities	1 to 2	45,722		19		(14		)	45,727
Long-term marketable securities		79,814		43		(28		)	79,829
Classified as restricted investments
U.S. government treasury securities	Less than 2	43,274		16		(6		)	43,284
Securities of government-sponsored entities	Less than 2	29,125		4		(16		)	29,113
Restricted investments		72,399		20		(22		)	72,397
Total marketable securities at December 31, 2013		$	295,638	$	102	$	(65	)	$	295,675
December 31, 2012:
Classified as current assets
Certificates of deposit	Less than 1	$	998	$	—	$	—		$	998
Corporate notes	Less than 1	19,169		3		(1		)	19,171
Commercial paper	Less than 1	9,995		2		—			9,997
U.S. government treasury securities	Less than 1	17,055		6		—			17,061
Securities of government-sponsored entities	Less than 1	91,151		27		—			91,178
Short-term marketable securities		138,368		38		(1		)	138,405
Classified as non-current assets
Corporate notes	1 to 2	23,293		—		(17		)	23,276
U.S. government treasury securities	1 to 2	7,619		4		—			7,623
Securities of government-sponsored entities	1 to 2	53,493		22		(2		)	53,513
Long-term marketable securities		84,405		26		(19		)	84,412
Classified as restricted investments
U.S. government treasury securities	Less than 2	31,784		5		(1		)	31,788
Securities of government-sponsored entities	Less than 2	53,618		18		(1		)	53,635
Restricted investments		85,402		23		(2		)	85,423
Total marketable securities at December 31, 2012		$	308,175	$	87	$	(22	)	$	308,240

As of December 31, 2013, the Company had no investments that were in a significant unrealized loss position. The Company reviews its investments to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value. The Company maintains an investment portfolio of various holdings, types and maturities. The Company does not hold derivative financial investments. The Company places its cash investments in instruments that meet high credit quality standards, as specified in its investment policy guidelines. These guidelines also limit the amount of credit exposure to any one issue, issuer or type of instrument.