Marketable Securities
 12 Months Ended
Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]  
Marketable Securities
Marketable Securities
The table below summarizes the Company’s available-for-sale marketable securities' amortized cost, gross unrealized gains, gross unrealized losses, and fair value by significant investment category recorded as short-term marketable securities or long-term marketable securities as of December 31, 2015 (refer to Note 2 for discussion of our fair value hierarchy). The Company had no marketable securities as of December 31, 2014.
 
Amortized Cost
 
Gross Unrealized Gains
 
Gross Unrealized Losses
 
Fair Value
 
Short-term Marketable Securities
 
Long-term Marketable Securities
Level 1:
 
 
 
 
 
 
 
 
 
 
 
U.S. Treasuries
$
4,017

 
$
—

 
$
(10
)
 
$
4,007

 
$
2,004

 
$
2,003

U.S. government agencies
3,656

 
—

 
(9
)
 
3,647

 
1,556

 
2,091

Subtotal
7,673

 
—

 
(19
)
 
7,654

 
3,560

 
4,094

Level 2:
 
 
 
 
 
 
 
 
 
 
 
Commercial paper
3,998

 
—

 
—

 
3,998

 
3,998

 
—

Corporate securities
42,065

 
1

 
(98
)
 
41,968

 
26,314

 
15,654

Subtotal
46,063

 
1

 
(98
)
 
45,966

 
30,312

 
15,654

Total
$
53,736

 
$
1

 
$
(117
)
 
$
53,620

 
$
33,872

 
$
19,748

 
 
 
 
 
 
 
 
 
 
 
 

The amortized cost and fair value of short-term and long-term marketable securities as of December 31, 2015 are shown below by contractual maturity. Actual maturities may differ from contractual maturities as securities may be restructured, called, or prepaid.
 
Amortized Cost
 
Fair Value
Due to mature:
 
 
 
Less than one year
$
33,929

 
$
33,872

One to two years
19,807

 
19,748

Total
$
53,736

 
$
53,620

 
 
 
 

No realized gains and losses were recognized on the sale of marketable securities for any of the periods presented. As of December 31, 2015, net unrealized losses of $116, net of tax, were included in accumulated other comprehensive loss in the accompanying consolidated balance sheets. There were no transfers between Level 1 and Level 2 fair value measurements during the year ended December 31, 2015, and there were no changes in the valuation techniques used by the Company.