Stock-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Options (in shares):
Outstanding beginning of the period (in shares)	4,353,167
Granted (in shares)	0	0
Forfeited (in shares)	(45,719)
Exercised (in shares)	(668,220)
Outstanding end of the period (in shares)	3,639,228		4,353,167
Exercisable (in shares)	3,376,057
Weighted-Average Exercise Price (in dollars per share):
Outstanding beginning of the period (in dollars per share)	$ 14.32
Granted (in dollars per share)	0
Forfeited (in dollars per share)	21.47
Exercised (in dollars per share)	14.15
Outstanding end of the period (in dollars per share)	14.26		$ 14.32
Exercisable (in dollars per share)	$ 13.97
Outstanding, weighted-average remaining contractual term (years)	5 years 1 month 6 days		5 years 7 months 6 days
Exercisable, weighted-average remaining contractual term (years)	4 years 10 months 24 days
Outstanding, aggregate intrinsic value	$ 142,764		$ 120,714
Exercisable, aggregate intrinsic value	133,426
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options exercised intrinsic value	18,900	$ 53,300
Options vested in period fair value	2,500	$ 3,900
Options unrecognized compensation expense	$ 1,600
Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options unrecognized compensation expense, period for recognition (years)	1 year
Class A Common Stock | Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Expiration period (years)	10 years
Minimum | Class A Common Stock | Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Award vesting period (years)	3 years
Maximum | Class A Common Stock | Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Award vesting period (years)	4 years