Stock-based Compensation (Tables)

6 Months Ended

Jun. 30, 2019

Stock-based Compensation

Summary of stock option activity

				Remaining	Aggregate
		Exercise		Contractual Term	Intrinsic Value
	Shares	Price		(in years)	(in thousands)(1)
Balance at December 31, 2018	2,620,295	$	20.40	1.49	$	25,697
Granted	—	$	—	—	$	—
Exercised	(573,806)	$	20.00	—	$	9,905
Forfeited/canceled	—	$	—	—	$	—
Balance at June 30, 2019	2,046,489	$	20.52	1.00	$	42,616
Vested and exercisable as of June 30, 2019	2,046,489	$	20.52	1.00	$	42,616

(1) The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the closing stock price of our Class A common stock as of the respective date.

Summary of additional information regarding exercisable and vested stock options

	Stock Options Exercisable
	and Vested
		Weighted-
		Average
	Number of	Remaining Life
Range of exercise prices	Shares	(in years)
$20.00	1,926,489	0.95
$28.80	120,000	1.82
$20.00 - $28.80	2,046,489	1.00

Summary of activities for unvested RSUs

	Unvested Restricted Stock Units
		Weighted-Average
	Number of	Grant-Date
	Shares	Fair Value
Unvested at December 31, 2018	1,055,325	$	41.66
Granted	670,279	$	39.64
Vested	(252,674)	$	35.11
Forfeited/canceled	(168,579)	$	29.67
Unvested at June 30, 2019	1,304,351	$	43.44
Expected to vest after June 30, 2019	1,395,739	$	43.29