Stock-Based Compensation - Summary Of Changes In CSEs Outstanding (Details) - Common stock equivalents	9 Months Ended
	Sep. 30, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Base fee percentage (up to)	50.00%
Common Stock Equivalents (CSEs) [Roll Forward]
Outstanding at December 31, 2017 (in shares) | shares	110,013
Granted (in shares) | shares	4,172
Converted to common shares upon grant (in shares) | shares	(5,075)
Outstanding at September 30, 2018 (in shares) | shares	109,110
Per Share Weighted Average Grant Date Fair Value [Roll Forward]
Outstanding at December 31, 2017 (in dollars per share) | $ / shares	$ 23.19
Granted (in dollars per share) | $ / shares	133.35
Converted to common shares upon grant (in dollars per share) | $ / shares	84.41
Outstanding at September 30, 2018 (in dollars per share) | $ / shares	$ 24.51