Share-Based compensation - Weighted Average Contractual Life and Exercise Price (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Options
Options outstanding	2,604,023	5,329,515	7,042,377
Options outstanding and vested | shares	2,583,523
Options vested		5,261,947
Options unvested		67,568
Weighted Average Remaining Contractual Life
Options outstanding		3 years 6 months 18 days
Options vested	5 years 10 months 6 days	3 years 6 months 14 days
Options unvested		4 years 8 months 15 days
Weighted Average Exercise Price
Options outstanding	$ 1.03	$ 1.06	$ 1.01
Options vested	$ 1.00	1.05
Options unvested		$ 1.23
Employee Stock Option [Member]
Number of Options
Options vested	20,500