Stockholders’ deficit and stock-based compensation - Volta stock (Details)	3 Months Ended
	Mar. 31, 2022 subsidiary shares	Feb. 07, 2021 subsidiary
Common Stock
Class of Stock [Line Items]
Conversion ratio	1
Preferred Stock | Volta Charter
Class of Stock [Line Items]
Number of shares authorized (in shares) | shares	10,000,000
Stock issued (in shares) | shares	0
Class A Common Stock
Class of Stock [Line Items]
Common stock, votes per share		1
Class A Common Stock | Common Stock
Class of Stock [Line Items]
Common stock, votes per share	1
Class B Common Stock | Common Stock
Class of Stock [Line Items]
Common stock, votes per share	10