Cash and Investments in Marketable Securities

3 Months Ended

Mar. 31, 2019

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, are as follows (in thousands):

	Estimated Fair Value at
	March 31, 2019		December 31, 2018
Cash and cash equivalents	$	106,752	$	194,905
Short-term investments		1,281,913		1,140,445
Long-term investments		455,867		582,889
Total cash and investments in marketable securities	$	1,844,532	$	1,918,239

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 March 31, 2019 and December 31, 2018, all of our long-term investments had maturities between one and two years.

Gross unrealized gains and losses were not significant at either March 31, 2019 or December 31, 2018. During the three months ended March 31, 2018, we sold available-for-sale securities totaling $12.0 million, and during the three months ended March 31, 2019, we sold no available-for-sale securities. Gross realized gains and losses on those 2018 sales were not significant. The cost of securities sold is based on the specific identification method.

Under the terms of our 7.75% senior secured notes due October 2020, we are required to maintain a minimum cash and investments in marketable securities balance of $60.0 million.

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

			Estimated Fair Value at
	Fair Value Hierarchy Level		March 31, 2019		December 31, 2018
Corporate notes and bonds		2	$	1,363,836	$	1,288,986
Corporate commercial paper		2		412,372		498,048
Obligations of U.S. government agencies		2		13,005		12,977
Available-for-sale investments				1,789,213		1,800,011
Money market funds		1		42,171		105,656
Certificate of deposit	N/A			6,759		6,760
Cash	N/A			6,389		5,812
Total cash and investments in marketable securities			$	1,844,532	$	1,918,239

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 for identical or similar assets or liabilities 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.

We use a market approach to value our Level 2 investments. The disclosed fair value related to our investments is based on market prices from a variety of industry standard data providers and generally represents quoted prices for similar assets in active markets or has been derived from observable market data. During the three months ended March 31, 2019 and 2018, there were no transfers between Level 1 and Level 2 of the fair value hierarchy.

Additionally, as of March 31, 2019, based on a discounted cash flow analysis using Level 3 inputs including financial discount rates, we believe the fair value of the $250.0 million in principal amount of our 7.75% senior secured notes due October 2020 is approximately $257.2 million. We may redeem some or all of these notes at a redemption price equal to 102% of the principal amount of the notes if the redemption date is prior to October 5, 2019, or 100% of the principal amount of the notes if the redemption date is on or after October 5, 2019, plus, in each case, accrued and unpaid interest to the applicable redemption date.