Stock-Based Compensation Expense - Summary of Restricted Stock and Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) [Member]	3 Months Ended
	Mar. 31, 2020 $ / shares shares
Shares
Unvested balance, Beginning balance (in shares) | shares	2,936,924
Granted (in shares) | shares	1,181,721
Vested (in shares) | shares	(308,333)
Forfeited (in shares) | shares	(94,970)
Unvested balance, Ending balance (in shares) | shares	3,715,342
Weighted-Average Grant Date Fair Value
Unvested balance, Beginning balance (in dollars per share) | $ / shares	$ 32.43
Granted (in dollars per share) | $ / shares	59.96
Vested (in dollars per share) | $ / shares	25.87
Forfeited (in dollars per share) | $ / shares	33.72
Unvested balance, Ending Balance (in dollars per share) | $ / shares	$ 41.71