Marketable Securities and Equity Investments
 12 Months Ended
Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]  
Marketable Securities and Equity Investments
Marketable Securities and Equity Investments
A summary of the Company’s cash equivalents and marketable securities, which are recorded at fair value (and do not include $2.3 billion and $1.4 billion of cash as of December 31, 2019 and 2018, respectively), is shown below:
 
Amortized Cost
 
Gross
Unrealized
Gains
 
Gross
Unrealized
Losses
 
Fair Value
 
(in thousands)
As of December 31, 2019
 
 
 
 
 
 
 
Cash equivalents:
 
 
 
 
 
 
 
Money market funds
$
791,039

 
$
—

 
$
—

 
$
791,039

Corporate debt securities
6,070

 
—

 
—

 
6,070

Commercial paper
29,470

 
3

 
(1
)
 
29,472

Total cash equivalents
826,579

 
3

 
(1
)
 
826,581

Marketable securities:
 
 
 
 
 
 
 
Government-sponsored enterprise securities
12,689

 
44

 
—

 
12,733

Corporate debt securities
301,458

 
391

 
(50
)
 
301,799

Commercial paper
102,240

 
121

 
(5
)
 
102,356

Total marketable debt securities
416,387

 
556

 
(55
)
 
416,888

Corporate equity securities
113,829

 
168,255

 
—

 
282,084

Total marketable securities
$
530,216

 
$
168,811

 
$
(55
)
 
$
698,972

 
 
 
 
 
 
 
 
As of December 31, 2018
 
 
 
 
 
 
 
Cash equivalents:
 
 
 
 
 
 
 
Money market funds
$
1,226,603

 
$
—

 
$
—

 
$
1,226,603

U.S. Treasury securities
5,967

 
—

 
(1
)
 
5,966

Government-sponsored enterprise securities
7,124

 
—

 
(1
)
 
7,123

Commercial paper
58,271

 
—

 
(3
)
 
58,268

Total cash equivalents
1,297,965

 
—

 
(5
)
 
1,297,960

Marketable securities:
 
 
 
 
 
 
 
U.S Treasury securities
6,026

 
—

 
—

 
6,026

Government-sponsored enterprise securities
10,704

 
—

 
—

 
10,704

Corporate debt securities
234,088

 
27

 
(450
)
 
233,665

Commercial paper
100,498

 
—

 
(108
)
 
100,390

Total marketable debt securities
351,316

 
27

 
(558
)
 
350,785

Corporate equity securities
133,157

 
40,619

 
(6,453
)
 
167,323

Total marketable securities
$
484,473

 
$
40,646

 
$
(7,011
)
 
$
518,108

Available-for-sale debt securities were classified on the Company’s consolidated balance sheets as follows:
 
As of December 31,
 
2019
 
2018
 
(in thousands)
Cash and cash equivalents
$
826,581

 
$
1,297,960

Marketable securities
416,888

 
350,785

Total
$
1,243,469

 
$
1,648,745


Available-for-sale debt securities by contractual maturity were as follows:
 
As of December 31,
 
2019
 
2018
 
(in thousands)
Matures within one year
$
1,137,942

 
$
1,647,500

Matures after one year through five years
105,527

 
1,245

Total
$
1,243,469

 
$
1,648,745


The Company has a limited number of available-for-sale debt securities in insignificant loss positions as of December 31, 2019, which it does not intend to sell and has concluded it will not be required to sell before recovery of the amortized costs for the investments at maturity. The Company did not record any charges for other-than-temporary declines in the fair value of available-for-sale debt securities or gross realized gains or losses in 2019, 2018 or 2017.
As of December 31, 2019 and 2018, the total fair value of the Company’s strategic investments in the common stock of publicly traded companies, which was primarily related to its investment in CRISPR, was $282.1 million and $167.3 million, respectively, and was classified as “Marketable securities” on its consolidated balance sheets.
Pursuant to the adoption of ASU 2016-01 on January 1, 2018, the Company began recording changes in the fair value of its investments in strategic corporate equity securities, which are primarily attributable to its investment in CRISPR, to “Other income (expense), net” in the Company’s consolidated statements of operations. Prior to its adoption of ASU 2016-01, the Company recorded changes in the fair value of its investments in corporate equity securities to “Accumulated other comprehensive (loss) income” on its consolidated balance sheet until the related gains or losses were realized. The Company continues to record unrealized gains (losses) on available-for-sale debt securities as a component of “Accumulated other comprehensive (loss) income” until such gains and losses are realized.
During the year ended December 31, 2019 and 2018, the Company recorded unrealized gains of $132.5 million and $2.6 million, respectively, which were primarily related to the Company’s strategic investment in CRISPR. As noted above, unrealized gains or losses were recorded to “Accumulated other comprehensive (loss) income” during the year ended December 31, 2017.
During the year ended December 31, 2019, the Company recorded realized gains of $65.1 million related to sales of CRISPR’s common stock. The Company utilized a weighted-average cost basis to calculate the realized gain. There were no sales of CRISPR’s common stock in the years ended December 31, 2018 or 2017.
As of December 31, 2019, the carrying value of the Company’s equity investments without readily determinable fair values, which are recorded in “Other assets” on its consolidated balance sheets, was $40.8 million.