Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2020

Earnings Per Share [Abstract]

Basic and diluted net loss per share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Numerator:
Net loss attributable to common stockholders ($ in millions)	$	(30.9)	$	(31.1)	$	(88.4)	$	(75.8)
Denominator:
Weighted average common shares outstanding — basic and diluted	53,997,315		11,178,924		25,935,362		11,079,303
Net loss per share attributable to common stockholders — basic and diluted	$	(0.57)	$	(2.78)	$	(3.41)	$	(6.84)

Antidilutive potential common shares

The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:

	As of September 30,
	2020	2019
Options to purchase common stock	4,814,924	3,925,395
Convertible preferred stock (as converted to common stock)	—	31,557,107
	4,814,924	35,482,502