Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2016

Equity [Abstract]

Summary of Equity Incentive Plan Activity

Equity incentive plan activity for the three months ended March 31, 2016 is summarized as follows:

Equity Incentive Plan Activity	Shares Available for Grant
Balance at December 31, 2015	4,991,583
Authorized	3,166,714
Granted	(1,856,207	)
Forfeited	241,205
Shares withheld for taxes and not issued	51,106
Balance at March 31, 2016	6,594,401

Summary of Stock Option Activity under the Company's Equity-Based Plans

The following table summarizes stock option activity under the Company’s equity-based plans for the three months ended March 31, 2016:

Stock Options Activity	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value (in thousands)
Balance at December 31, 2015	4,446,149		$	8.96	7.56	$	52,108
Exercised	(190,608	)	2.64
Forfeited	(145,213	)	24.35
Balance at March 31, 2016	4,110,328		$	8.71	7.31	$	30,286
Exercisable at March 31, 2016	2,331,709		$	6.67	6.97	$	20,620
Vested and expected to vest at March 31, 2016	3,993,724		$	8.53	7.29	$	29,845

Summary of Restricted Stock Unit Activity under the Company's Equity-Based Plans

The following table summarizes RSU activity under the Company’s equity-based plans for the three months ended March 31, 2016:

Restricted Stock Unit Activity	Number of Units		Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2015	956,687		$	28.03
Granted	1,856,207		17.80
Vested	(207,496	)	26.50
Forfeited	(72,118	)	21.80
Nonvested at March 31, 2016	2,533,280		$	20.84

Summary of Performance Based Restricted Stock Unit Activity

The following table summarizes PSU activity under the Company’s equity-based plans for the three months ended March 31, 2016:

Performance Based Restricted Stock Unit Activity	Number of Units		Weighted-Average Grant Date Fair Value
Outstanding units at December 31, 2015	173,286		$	33.51
Forfeited	(23,874	)	$	33.51
Outstanding units at March 31, 2016	149,412		$	33.51

Summary of Significant Assumptions Used to Estimate Fair Value of Stock Options under Black-Scholes Model

The fair value of stock-based awards is estimated on the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions:

Stock Option Assumptions	Three Months Ended March 31,
	2016	2015
Expected term (in years)	N/A	6.08
Expected volatility	N/A	39	%
Risk-free interest rate	N/A	1.74	%
Expected dividend yield	N/A	0	%

Summary of Significant Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plans under Black-Scholes Model

ESPP Assumptions	Three Months Ended March 31,
	2016		2015
Expected term (in years)	0.50		0.50
Expected volatility	76	%	33	%
Risk-free interest rate	0.33	%	0.07	%
Expected dividend yield	0	%	0	%

Summary of Stock-based Compensation Expense

Stock-based compensation expense for stock-based awards made to the Company’s employees pursuant to the equity plans was as follows (in thousands): 

	Three Months Ended March 31,
	2016		2015
Cost of providing services	$	1,815	$	758
Sales and marketing	1,985		917
General and administrative	2,974		2,021
Systems development and programming costs	623		224
	$	7,397	$	3,920