Stock-based Compensation - Additional Information (Detail) - USD ($)		1 Months Ended			12 Months Ended
	Jun. 06, 2019	May 31, 2020	Apr. 30, 2019	Apr. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 29, 2017	Apr. 17, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock option granted					0	0	0
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, aggregate intrinsic value					$ 0
Options outstanding, weighted-average remaining contractual term					3 years 2 months 19 days
Options exercisable, aggregate intrinsic value					$ 0
Options exercisable, weighted-average remaining contractual term					3 years 2 months 15 days
Outstanding non-vested options					15,000
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding non-vested restricted stock					3,000,000.0
Performance Units Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Performance period					3 years
Performance Units Awards | 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued			185,000
Performance Units Awards | 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued				381,200
Performance Units Awards | 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued		332,773
Performance Units Awards | Condition One [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award description					The performance goals for the Performance Units are tied to our total shareholder return for the performance period as compared to total shareholder return for a peer group determined by the Compensation Committee. These goals are considered to be market conditions under the relevant accounting standards and the market conditions were factored into the determination of the fair value of the respective Performance Units.  For the Performance Units granted in April 2018, the recipients will receive a target number of shares if our total shareholder return during the performance period, when compared to the peer group, is at the 50th percentile. For the Performance Units granted in April 2019 and April 2020, the recipients will receive the target number of shares if our total shareholder return during the performance period, when compared to the peer group, is at the 55th percentile. If our total shareholder return during the performance period, when compared to the peer group, is at the 75th percentile or higher, then the recipients will receive two times the target number of shares. If our total shareholder return during the performance period, when compared to the peer group, is at the 25th percentile, then the recipients will only receive one-half of the target number of shares. If our total shareholder return during the performance period, when compared to the peer group, is between the 25th and target percentile, or the target and 75th percentile, then the shares to be received by the recipients will be determined using linear interpolation for levels of achievement between these points.   For the Performance Units granted in April 2018, the payout is based on relative performance and does not have an absolute performance requirement. For the Performance Units granted in April 2019 and April 2020, the payout shall not exceed the target number of shares if our total shareholder return is negative or zero. Additionally, the Performance Units granted in April 2020 will not pay out if our total shareholder return is not equal to or greater than the total stockholder return of the S&P 500 Index for the Performance Period.
Phantom Share Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period		3 years
Award description		Mr. Hendricks may earn from 0% to 200% of a target award of 298,500 phantom units based on our achievement of the same performance conditions over the same Performance Period that applies to the Performance Units granted in April 2020, as described above. Earned Phantom Units, if any, will be settled in 2023, following completion of the three-year Performance Period, in a cash payment equal to the number of earned phantom units multiplied by our average trading price per share over the twenty consecutive trading days ending March 31, 2023.
Performance completion year		2023
Performance Period		3 years
Grant date fair value		$ 1,200,000
Expense recognized					$ 600,000
Chief Executive Officer and President | Phantom Share Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of units awardable based on performance conditions		298,500,000
Chief Executive Officer and President | Maximum | Phantom Share Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of target award vesting rights		200.00%
Chief Executive Officer and President | Minimum | Phantom Share Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of target award vesting rights		0.00%
Patterson-UTI Energy, Inc. 2014 Long-Term Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized for grant									9,100,000
Amended and Restated Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized for grant	28,400,000				28,400,000
Shares available for future issuance	9,500,000				4,986,392			9,800,000
Extended date for awards granted	Jun. 06, 2029
Amended and Restated Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option term					10 years
Amended and Restated Plan | Non Employee Director
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period					1 year
Performance Period					1 year
Amended and Restated Plan | Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period					3 years
Performance Period					3 years
Patterson-UTI Energy, Inc. 2005 Long-Term Incentive Plan | Non Employee Director | Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period					1 year
Performance Period					1 year
Patterson-UTI Energy, Inc. 2005 Long-Term Incentive Plan | Employees | Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Awards vesting period					3 years
Performance Period					3 years