Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended		12 Months Ended	32 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Sep. 30, 2020	Mar. 31, 2019
Equity
Cash dividend declared (in dollars per share)	$ 0.09	$ 0.27
Dividends declared		$ 13.0
Dividends paid		$ 12.8
Cactus LLC
Equity
Ownership interest		63.10%		62.80%
Cactus Inc
Equity
Cash distributions to unit holders		$ 26.5	$ 9.9
CW Unit Holders other than Cactus, Inc.
Equity
Pro rate distributions made to other members		$ 15.6	$ 5.9
March 2019 Secondary Offering
Equity
Offering expenses						$ 1.0
Class A Common Stock
Equity
Common stock, shares outstanding (in shares)	47,547,000	47,547,000		47,159,000	47,547,000
Shares outstanding, percentage of total voting power	63.10%	63.10%			63.10%
Class A Common Stock | Cactus Wellhead LLC Agreement
Equity
CW Unit redemptions (in shares)		142,000	9,200,000		32,700,000
Class B Common Stock
Equity
Common stock, shares outstanding (in shares)	27,816,000	27,816,000		27,958,000	27,816,000
Shares outstanding, percentage of total voting power	36.90%	36.90%			36.90%