Income Taxes (Tables)
 12 Months Ended
Dec. 31, 2015
Income Tax Disclosure [Abstract]  
Components of loss before income taxes
The following table presents domestic and foreign components of loss before income taxes for the periods presented (in thousands of dollars):
 
Year Ended December 31,
 
2013
 
2014
 
2015
Domestic
$
(187
)
 
$
(11,222
)
 
$
(19,917
)
International
—

 
(1,767
)
 
(2,536
)
Total
$
(187
)
 
$
(12,989
)
 
$
(22,453
)
Reconciliation of differences between statutory U.S. federal and effective income tax rate
Taxes computed at the statutory U.S. federal income tax rate of 34% are reconciled to the provision for income taxes as follows (in thousands of dollars):
 
Year Ended December 31,
 
2013
 
2014
 
2015
Effective tax rate
0
%
 
0
%
 
0
%
Statutory rate of 34%
$
(64
)
 
$
(4,416
)
 
$
(7,634
)
State taxes, net of federal benefit
(4
)
 
(256
)
 
(615
)
Foreign rate differential
—

 
245

 
346

Stock-based compensation permanent differences
182

 
464

 
836

Meals and entertainment permanent differences
26

 
232

 
385

Miscellaneous permanent differences
13

 
32

 
165

Warrant fair market value adjustment
—

 
229

 
(59
)
Other adjustments
—

 
474

 
(3
)
Change in valuation allowance
(153
)
 
2,996

 
6,579

Provision for income taxes
$
—

 
$
—

 
$
—
Components of current and long-term deferred tax assets (liabilities)
Components of the current and long-term deferred tax assets were as follows (in thousands of dollars):
 
December 31,
 
2014
 
2015
Current:
 

 
 

Accrued expenses
$
754

 
$
882

Valuation allowance
(552
)
 
(642
)
Total current deferred tax asset
$
202

 
$
240

Long-term:
 

 
 
Stock-based compensation
$
360

 
$
854

Future benefit of carry forward losses
9,961

 
17,946

Other accruals
160

 
488

Valuation allowance
(7,740
)
 
(14,229
)
Total long-term deferred tax asset
$
2,741

 
$
5,059

Components of current and long-term deferred tax liabilities were as follows (in thousands of dollars):
 
December 31,
 
2014
 
2015
Current:
 

 
 

Other accruals
$
(19
)
 
$
(20
)
Total current deferred tax liability
$
(19
)
 
$
(20
)
Long-term:
 

 
 
Amortization
$
(2,090
)
 
$
(3,688
)
Depreciation
(814
)
 
(1,591
)
Other accruals
(20
)
 
—

Total long-term deferred tax liability
$
(2,924
)
 
$
(5,279
)
Net deferred tax assets (liabilities)
$
—

 
$
—