Net Income per Share - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income attributable to Liberty Oilfield Services Inc. Stockholders	$ (34,502)	$ 10,998	$ (78,553)	$ 51,151
Denominator, Basic [Abstract]
Basic weighted average shares outstanding (in shares)	84,937	74,173	83,299	70,026
Basic net income per share attributable to Liberty Oilfield Services Inc. Stockholders (in dollars per share)	$ (0.41)	$ 0.15	$ (0.94)	$ 0.73
Numerator, Diluted [Abstract]
Net income attributable to Liberty Oilfield Services Inc. Stockholders	$ (34,502)	$ 10,998	$ (78,553)	$ 51,151
Effect of exchange of the shares of Class B Common Stock for shares of Class A Common Stock	0	5,435	0	26,776
Net Income (Loss) Available to Common Stockholders, Diluted	$ (34,502)	$ 16,433	$ (78,553)	$ 77,927
Denominator, Diluted [Abstract]
Basic weighted average shares outstanding (in shares)	84,937	74,173	83,299	70,026
Effect of dilutive securities:
Restricted stock (in shares)	0	545	0	567
Restricted stock units (in shares)	0	1,690	0	1,757
Class B Common Stock (in shares)	0	36,656	0	36,656
Diluted weighted average shares outstanding (in shares)	84,937	113,064	83,299	109,006
Diluted net income per share attributable to Liberty Oilfield Services Inc. Stockholders (in dollars per share)	$ (0.41)	$ 0.15	$ (0.94)	$ 0.71