Organization and Nature of Operations - IPO and TRA (Details) $ / shares in Units, $ in Millions				8 Months Ended	9 Months Ended	12 Months Ended
	Jul. 16, 2018 shares	Feb. 14, 2018 USD ($) shares	Feb. 12, 2018 USD ($) $ / shares shares	Sep. 30, 2018 USD ($) $ / shares	Sep. 30, 2018 Center $ / shares	Dec. 31, 2017 USD ($)
Organization and Nature of Operations
Number of U.S. service centers | Center					15
Number of service centers in Eastern Australia | Center					1
Initial Public Offering
Offering costs | $				$ 2.8		$ 2.2
Tax Receivable Agreement
Tax savings payable to TRA Holders (as a percent)	85.00%		85.00%
Tax savings benefit recorded as APIC (as a percent)			15.00%
Cactus LLC
Initial Public Offering
Net proceeds from IPO | $			$ 469.6
Cactus LLC | Term loan facility
Initial Public Offering
Repayments of debt | $			251.0
Cactus LLC
Initial Public Offering
Ownership interest				50.30%	50.30%
Members' Equity (Deficit) | Cactus LLC
Initial Public Offering
Redeem CW Units from certain direct and indirect owners | $			$ 216.4
Redeem CW Units from certain direct and indirect owners (in units) | shares			8,667,841
Class A Common Stock
Initial Public Offering
Common stock, par value | $ / shares				$ 0.01	$ 0.01
Class B Common Stock
Initial Public Offering
Number of shares issued | shares			51,889,772
Common stock, par value | $ / shares			$ 0.01	$ 0.01	$ 0.01
Redeem CW Units from certain direct and indirect owners (in units) | shares	11,196,562
Class B Common Stock | Cactus LLC
Initial Public Offering
Redeem CW Units from certain direct and indirect owners (in units) | shares		3,450,000
IPO | Class A Common Stock
Initial Public Offering
Number of shares issued | shares			23,000,000
Common stock, par value | $ / shares			$ 0.01
Price per share | $ / shares			$ 19.00
Net proceeds from IPO | $			$ 408.0
Underwriter's option | Class A Common Stock
Initial Public Offering
Number of shares issued | shares	1,196,562	3,450,000
Net proceeds from IPO | $		$ 61.6