Stock-based Awards (Tables)

12 Months Ended

Dec. 31, 2014

Stock based Awards

Summary of stock option activity

		Weighted-		Weighted-
		Average		Average	Aggregate
	Number of	Exercise		Remaining	Intrinsic
	Options	Price		Contract Life	Value (1)
				(in years)	(in millions)
Outstanding at December 31, 2013	18,363,144	$	4.89	7.17
Granted	11,076,585		15.99
Exercised	(2,751,389)		2.15
Canceled/forfeited	(1,098,464)		9.66
Outstanding at December 31, 2014	25,589,876	$	9.79	7.55	$	365.0
Vested and expected to vest at December 31, 2014	24,572,090	$	9.73	7.49	$	353.0
Exercisable at December 31, 2014	18,291,866	$	9.12	6.97	$	281.5

The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock option awards and the closing price of the Company's common stock of $22.90 on December 31, 2014.

Schedule of activity in connection with restricted stock

		Weighted-
		Average
	Number of	Grant Date
	Shares	Fair Value
Non-vested — December 31, 2013	55,555	$	3.56
Granted	—		—
Vested	(55,555)		3.56
Canceled/forfeited	—		—
Non-vested — December 31, 2014	—	$	—

Schedule of activity in connection with the restricted stock units

		Weighted-
		Average
	Number of	Grant Date
	Shares	Fair Value
Non-vested — December 31, 2013	—	$	—
Granted	905,767		12.35
Vested	(12,263)		21.97
Canceled/forfeited	(65,507)		10.44
Non-vested — December 31, 2014	827,997	$	12.36

Schedule of fair value of awards granted to employees using the Black Scholes option pricing model

	Year Ended
	December 31,
	2014		2013		2012
Risk-free interest rate	1.93	%	1.41	%	0.96	%
Expected term (years)	6.24		6.06		6.00
Expected volatility	58	%	61	%	60	%
Dividend yield	—		—		—

Schedule of stock-based compensation cost relating to stock options and restricted stock awards

	Year Ended
	December 31,
	2014		2013		2012
Cost of revenue	$	454	$	141	$	122
Sales and marketing		4,743		2,561		1,571
Technology and development		5,013		1,762		1,428
General and administrative		19,123		4,882		7,199
Total stock-based compensation expense		29,333		9,346		10,320
Amount capitalized to internal software use		1,249		540		214
Total stock-based compensation cost	$	30,582	$	9,886	$	10,534