Cash and Investments in Marketable Securities

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Cash and Investments in Marketable Securities

Note 2 — Cash and Investments in Marketable Securities

Cash and investments in marketable securities, including cash equivalents and restricted cash, are as follows (in thousands):

	Estimated Fair Value at
	December 31, 2014		December 31, 2013
Cash and cash equivalents	$	12,365	$	39,067
Short-term investments		225,459		197,959
Restricted cash		25,000		25,000
Total cash and investments in marketable securities	$	262,824	$	262,026

We invest in liquid, high quality debt securities. Our investments in debt securities are subject to interest rate risk. To minimize the exposure due to an adverse shift in interest rates, we invest in securities with maturities of two years or less and maintain a weighted average maturity of one year or less. As of December 31, 2014 and 2013, all of our investments had contractual maturities of one year or less and were classified as short-term.

Gross unrealized gains and losses were not significant at either December 31, 2014 or 2013. During the years ended December 31, 2014, 2013 and 2012, we sold available-for-sale securities totaling $21.7 million, $2.9 million and $5.4 million respectively, and realized gains and losses were not significant in any of those periods.

Restricted cash of $25.0 million is required to be maintained in a separate account until July 1, 2015 under the terms of our 12% senior secured notes due July 2017. Upon release of this restriction on July 1, 2015, a covenant of the senior secured notes requires that the aggregate balance of our unrestricted cash and cash equivalents at the end of any two consecutive fiscal quarters may not be less than $25.0 million, subject to certain conditions (see Note 5).

Our portfolio of cash and investments in marketable securities includes (in thousands):

	Fair  Value Hierarchy Level		Estimated Fair Value at
			December 31, 2014		December 31, 2013
Corporate notes and bonds		2	$	182,544	$	138,515
Corporate commercial paper		2		42,915		59,444
Available-for-sale investments				225,459		197,959
Money market funds		1		11,229		26,453
Cash, including restricted cash		N/A		26,136		37,614
Total cash and investments in marketable securities			$	262,824	$	262,026

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

Level 2 — Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3 — Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

All of our investments are categorized as Level 1 or Level 2, as explained in the table above. We use a market approach to value our Level 2 investments. During the years ended December 31, 2014, 2013 and 2012, there were no transfers between Level 1 and Level 2 of the fair value hierarchy.

At December 31, 2014 and 2013, we had letter of credit arrangements in favor of a landlord and certain vendors totaling $2.4 million. These letters of credit are secured by investments of similar amounts.