Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Schedules of changes in the allowance for doubtful accounts

The following table presents the changes in the allowance for doubtful accounts (in thousands):



	Year Ended December 31,
	2015			2014			2013
Balance at beginning of year	$	890		$	454		$	321
Provision	412			829			725
Acquisitions	—			400			295
Writeoffs, net of recoveries	(721		)	(793		)	(887		)
Balance at end of year	$	581		$	890		$	454

Schedule of estimated useful lives of property and equipment

The estimated useful lives of property and equipment are as follows:



Computer hardware and equipment	3 - 5 years
Purchased software and licenses	3 - 5 years
Furniture and fixtures	7 years
Leasehold improvements	Lesser of estimated useful life or lease term

Property and equipment consisted of the following (in thousands) at:



	December 31, 2015			December 31, 2014
Equipment (including equipment under capital lease of $6,199 and $3,028, respectively)	$	11,599		$	7,712
Furniture and fixtures (including furniture under capital lease of $143 and $0 at December 31, 2015 and 2014, respectively)	484			502
Leasehold improvements	819			574
Accumulated depreciation (including for equipment and furniture under capital lease of $2,218 and $1,194 at December 31, 2015 and 2014, respectively)	(6,901		)	(4,858		)
Property and equipment, net	$	6,001		$	3,930

Schedule of weighted-average grant-date fair value assumptions

The following table summarizes the weighted-average grant-date fair value of options granted in 2015, 2014, and 2013 and the assumptions used to develop their fair values. As there was no public market for its common stock prior to November 2014, the Company estimates the volatility of its common stock based on the volatility of publicly traded shares of comparable companies' common stock. The Company's decision to use the volatility of comparable stock was based upon the Company's assessment that this information is more representative of future stock price trends than the Company's historical volatility. The Company estimates the expected term using the simplified method, which calculates the expected term as the midpoint between the vesting date and the contractual termination date of each award. The dividend yield assumption is based on historical and expected future dividend payouts. The risk-free interest rate is based on observed market interest rates appropriate for the term of each options.



	Year Ended December 31,
	2015	2014	2013
Weighted average grant-date fair value of options	$3.01	$3.76	$0.91
Expected volatility	42.5% - 44.0%	54.1% - 55.2%	53.3%
Risk-free interest rate	1.7% - 1.9%	1.6% - 1.9%	1.6%
Expected life in years	5.93	6.29	6.29
Dividend yield	—	—	—