Share-Based Compensation - Stock Options (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares
Number of shares
Outstanding at beginning of period (in shares)	9,423,015
Granted (in shares)	262,838
Exercised (in shares)	(1,518,142)
Forfeited (in shares)	(47,063)
Outstanding at end of period (in shares)	8,120,648
Options exercisable (in shares)	4,482,647
Options unvested (in shares)	8,120,648
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 24.58
Granted (in dollars per share) | $ / shares	51.79
Exercised (in dollars per share) | $ / shares	10.81
Forfeited (in dollars per share) | $ / shares	37.46
Outstanding at end of period (in dollars per share) | $ / shares	27.96
Options exercisable (in dollars per share) | $ / shares	19.46
Options unvested (in dollars per share) | $ / shares	$ 27.96
Weighted Average Contractual Term and Aggregate Intrinsic Value
Weighted average remaining contractual term of options outstanding (in years)	7 years 5 months 26 days
Weighted average remaining contractual term of options exercisable (in years)	6 years 7 months 17 days
Weighted average remaining contractual term of options vested and expected to vest (in years)	7 years 5 months 26 days
Aggregate intrinsic value of options outstanding | $	$ 366,753
Aggregate intrinsic value of options exercisable | $	240,550
Aggregate intrinsic value of options vested and expected to vest | $	$ 366,753
Additional Disclosures
Unvested stock options expected to vest (in shares)	3,638,001
Stock options
Additional Disclosures
Share-based award term (in years)	10 years
Total unrecognized compensation cost | $	$ 73,546
Weighted average period for recognition of compensation cost	2 years 1 month 24 days
Stock options | Minimum
Additional Disclosures
Share-based award vesting period (in years)	3 years
Stock options | Maximum
Additional Disclosures
Share-based award vesting period (in years)	4 years