Cash and Investments in Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Cash and Investments in Marketable Securities, Including Cash Equivalents

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

	Estimated Fair Value at
	June 30, 2019		December 31, 2018
Cash and cash equivalents	$	85,424	$	194,905
Short-term investments	1,429,955		1,140,445
Long-term investments	276,305		582,889
Total cash and investments in marketable securities	$	1,791,684	$	1,918,239

Portfolio of Cash and Investments in Marketable Securities

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

		Estimated Fair Value at
	Fair Value Hierarchy Level	June 30, 2019		December 31, 2018
Corporate notes and bonds	2	$	1,283,731	$	1,288,986
Corporate commercial paper	2	427,091		498,048
Obligations of U.S. government agencies	2	13,006		12,977
Available-for-sale investments		1,723,828		1,800,011
Money market funds	1	58,690		105,656
Certificate of deposit	N/A	6,872		6,760
Cash	N/A	2,294		5,812
Total cash and investments in marketable securities		$	1,791,684	$	1,918,239