Warrant Transaction Agreements - Walmart Stores, Inc. Transaction Agreement (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Jul. 20, 2017
Warrants issued with the Walmart Stores, Inc transaction agreement
Warrant Transaction Agreements
Shares of common stock that can be purchased from warrants issued (in shares)						55,286,696
Reduction in revenue	$ 2.0	$ 1.6	$ 3.7	$ 3.2
Warrant shares vested (in shares)	20,368,782		20,368,782		20,368,782
Number of warrants exercised (in shares)	0	7,274,565	0	7,274,565
Walmart
Warrant Transaction Agreements
Number of warrants exercised (in shares)			13,094,217		13,094,217