XML 21 R11.htm IDEA: XBRL DOCUMENT v3.10.0.1
Cash and Cash Equivalents and Investments
 9 Months Ended
Sep. 30, 2018
Cash and Cash Equivalents and Investments [Abstract]  
Cash and Cash Equivalents Disclosure
Cash and Cash Equivalents and Investments
 
The fair value of cash and cash equivalents and investments held at September 30, 2018 and December 31, 2017 are as follows: 
 
 
As of September 30, 2018
 
 
Amortized Cost
 
Gross Unrealized Gains
 
Gross Unrealized Losses
 
Estimated Fair Value
 
 
(in thousands)
Cash and cash equivalents
 
$
48,902

 
$
—

 
$
—

 
$
48,902

Securities maturing within one year:
 
 
 
 
 
 
 
 
U.S. treasury securities
 
125,651

 
—

 
(63
)
 
125,588

Corporate debt securities
 
12,815

 
—

 
(8
)
 
12,807

Total short-term investments
 
$
138,466

 
$
—

 
$
(71
)
 
$
138,395

Total cash and cash equivalents and investments
 
$
187,368

 
$
—

 
$
(71
)
 
$
187,297

 
 
 
 
 
 
 
 
 
 
 
As of December 31, 2017
 
 
Amortized Cost
 
Gross Unrealized Gains
 
Gross Unrealized Losses
 
Estimated Fair Value
 
 
 
 
(in thousands)
 
 
Cash and cash equivalents
 
$
61,661

 
$
—

 
$
—

 
$
61,661

Securities maturing within one year:
 
 
 
 
 
 
 
 
U.S. treasury securities
 
222,316

 
—

 
(168
)
 
222,148

Corporate debt securities
 
27,033

 
—

 
(54
)
 
26,979

Total short-term investments
 
$
249,349

 
$
—

 
$
(222
)
 
$
249,127

Total cash and cash equivalents and investments
 
$
311,010

 
$
—

 
$
(222
)
 
$
310,788



There were no realized losses for the nine months ended September 30, 2018, and $7,000 in realized losses for the nine months ended September 30, 2017. The cost of securities sold is based on the specific identification method.