Annual report pursuant to Section 13 and 15(d)

Fair Value

v3.8.0.1
Fair Value
 12 Months Ended
Dec. 31, 2017
Fair Value Disclosures [Abstract]  
Fair Value Fair Value
 
We record cash equivalents and investments at fair value. Fair value is an exit price, representing the amount that would be received from the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. Fair value measurements are required to be disclosed by level within the following fair value hierarchy:
 
Level 1 — Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.
 
Level 2 — Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life.
 
Level 3 — Inputs lack observable market data to corroborate management’s estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.
 
When determining fair value, whenever possible we use observable market data and rely on unobservable inputs only when observable market data is not available.
 
The following fair value hierarchy tables categorize information regarding our financial assets and liabilities measured at fair value on a recurring basis at December 31, 2016 and 2017:
 
 
As of December 31, 2016
 
Fair Value Measurement Using
 
Quoted Prices in
Active Markets
for Identical
Instruments (Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Total
 
(in thousands)
Assets
 

 
 

 
 

Money market funds
$
55,752

 
$
—

 
$
55,752

Corporate debt securities
—

 
43,361

 
43,361

Total assets measured at fair value
$
55,752

 
$
43,361

 
$
99,113

 
As of December 31, 2017
 
Fair Value Measurement Using
 
Quoted Prices in
Active Markets
for Identical
Instruments (Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Total
 
(in thousands)
Assets
 

 
 

 
 

Money market funds
$
353,303

 
$
—

 
$
353,303

Corporate debt securities
—

 
1,250

 
1,250

Total assets measured at fair value
$
353,303

 
$
1,250

 
$
354,553


 
Our cash equivalents and short-term investments are classified as Level 2 within the fair value hierarchy because they are valued using professional pricing sources for identical or comparable instruments, rather than direct observations of quoted prices in active markets.

As of December 31, 2016 and 2017, we held no Level 3 assets or liabilities measured on a recurring basis. The fair value of our Convertible Promissory Note was calculated on a nonrecurring basis as of September 1, 2017 and is classified as a Level 3 measurement within the fair value hierarchy. Refer to Note 8 "Convertible Promissory Note Receivable" in the Notes to Consolidated Financial Statements for further details on the Convertible Promissory Note.

Refer to Note 9, "Debt Instruments", in the Notes to Consolidated Financial Statements for the carrying amount and estimated fair value of our convertible senior notes, which are not recorded at fair value as of December 31, 2017.