Supplemental Condensed Consolidated Financial Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018		Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 91,557				$ 701	$ 822		$ 893
Accounts receivable, net of allowance for doubtful accounts	122,123				111,512
Materials and supplies	505				505
Current derivative asset	0				721
Prepaid expenses and other	9,419				6,233
Total current assets	223,604				119,672
Oil and natural gas properties on the full cost method:
Proved properties	5,901,661				5,712,813
Unproved properties not being amortized	332,886				296,764
Drilling equipment	1,632,540				1,593,611
Gas gathering and processing equipment	751,715				726,236
Saltwater disposal systems	67,074				62,618
Corporate land and building	59,081				59,080
Transportation equipment	29,103				29,631
Other	56,750				53,439
Property, plant, and equipment, gross	8,830,810				8,534,192
Less accumulated depreciation, depletion, amortization, and impairment	6,325,160				6,151,450
Net property and equipment	2,505,650				2,382,742
Intercompany receivable	0				0
Goodwill	62,808				62,808
Investments	1,500				1,500
Other assets	27,203				14,730
Total assets	2,820,765	[1]			2,581,452
Current liabilities:
Accounts payable	143,552				112,648
Accrued liabilities	67,743				48,523
Income taxes payable	1,051				0
Current derivative liability	13,067				7,763
Current portion of other long-term liabilities	14,150			$ 15,750	13,002
Total current liabilities	239,563				181,936
Intercompany debt	0				0
Long-term debt					178,000
Bonds payable less debt issuance costs	643,921				642,276
Non-current derivative liability	1,542				0
Other long-term liabilities	101,410			109,940	100,203
Deferred income taxes	164,964			133,064	133,477
Shareholders' equity:
Preferred stock, $1.00 par value, 5,000,000 shares authorized, none issued	0				0
Common stock, $.20 par value, 175,000,000 shares authorized	10,414				10,280
Capital in excess of par value	626,746				535,815
Contributions from Unit	0				0
Accumulated other comprehensive income (loss)	(103)		$ (65)	63	63	53	$ 20	0
Retained earnings	830,680			$ 798,128	799,402
Total shareholders’ equity attributable to Unit Corporation	1,467,737				1,345,560
Non-controlling interests in consolidated subsidiaries	201,628				0
Total shareholders' equity	1,669,365				1,345,560	1,251,905		1,194,070
Total liabilities and shareholders' equity	2,820,765	[1]			2,581,452
Consolidating Adjustments [Member]
Current assets:
Cash and cash equivalents	0				0	0		0
Accounts receivable, net of allowance for doubtful accounts	0				0
Materials and supplies	0				0
Current derivative asset	0				0
Prepaid expenses and other	0				0
Total current assets	0				0
Oil and natural gas properties on the full cost method:
Proved properties	0				0
Unproved properties not being amortized	0				0
Drilling equipment	0				0
Gas gathering and processing equipment	0				0
Saltwater disposal systems	0				0
Corporate land and building	0				0
Transportation equipment	0				0
Other	0				0
Property, plant, and equipment, gross	0				0
Less accumulated depreciation, depletion, amortization, and impairment	0				0
Net property and equipment	0				0
Intercompany receivable	(907,907)				(1,155,725)
Goodwill	0				0
Investments	(1,248,309)				(1,044,709)
Other assets	0				0
Total assets	(2,156,216)				(2,200,434)
Current liabilities:
Accounts payable	0				0
Accrued liabilities	0				0
Income taxes payable	0
Current derivative liability	0				0
Current portion of other long-term liabilities	0				0
Total current liabilities	0				0
Intercompany debt	(907,382)				(1,155,725)
Long-term debt					0
Bonds payable less debt issuance costs	0				0
Non-current derivative liability	0
Other long-term liabilities	0				0
Deferred income taxes	0				0
Shareholders' equity:
Preferred stock, $1.00 par value, 5,000,000 shares authorized, none issued	0				0
Common stock, $.20 par value, 175,000,000 shares authorized	0				0
Capital in excess of par value	(242,963)				(61,470)
Contributions from Unit	(525)				0
Accumulated other comprehensive income (loss)	0				0
Retained earnings	(1,005,346)				(983,239)
Total shareholders’ equity attributable to Unit Corporation	(1,248,834)				(1,044,709)
Non-controlling interests in consolidated subsidiaries	0				0
Total shareholders' equity	(1,248,834)				(1,044,709)
Total liabilities and shareholders' equity	(2,156,216)				(2,200,434)
Parent [Member]
Current assets:
Cash and cash equivalents	82,267				510	504		517
Accounts receivable, net of allowance for doubtful accounts	1,374				154
Materials and supplies	0				0
Current derivative asset	0				721
Prepaid expenses and other	3,125				2,986
Total current assets	86,766				4,371
Oil and natural gas properties on the full cost method:
Proved properties	0				0
Unproved properties not being amortized	0				0
Drilling equipment	0				0
Gas gathering and processing equipment	0				0
Saltwater disposal systems	0				0
Corporate land and building	0				0
Transportation equipment	9,273				9,270
Other	28,506				28,039
Property, plant, and equipment, gross	37,779				37,309
Less accumulated depreciation, depletion, amortization, and impairment	25,922				21,268
Net property and equipment	11,857				16,041
Intercompany receivable	907,907				1,155,725
Goodwill	0				0
Investments	1,248,309				1,044,709
Other assets	5,605				5,373
Total assets	2,260,444				2,226,219
Current liabilities:
Accounts payable	28,116				13,124
Accrued liabilities	36,444				26,165
Income taxes payable	1,051
Current derivative liability	13,067				7,763
Current portion of other long-term liabilities	966				657
Total current liabilities	79,644				47,709
Intercompany debt	0				0
Long-term debt					178,000
Bonds payable less debt issuance costs	643,921				642,276
Non-current derivative liability	1,542
Other long-term liabilities	12,790				11,257
Deferred income taxes	54,707				1,480
Shareholders' equity:
Preferred stock, $1.00 par value, 5,000,000 shares authorized, none issued	0				0
Common stock, $.20 par value, 175,000,000 shares authorized	10,414				10,280
Capital in excess of par value	626,746				535,815
Contributions from Unit	0				0
Accumulated other comprehensive income (loss)	0				0
Retained earnings	830,680				799,402
Total shareholders’ equity attributable to Unit Corporation	1,467,840				1,345,497
Non-controlling interests in consolidated subsidiaries	0				0
Total shareholders' equity	1,467,840				1,345,497
Total liabilities and shareholders' equity	2,260,444				2,226,219
Combined Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	251				191	318		376
Accounts receivable, net of allowance for doubtful accounts	92,078				83,442
Materials and supplies	505				505
Current derivative asset	0				0
Prepaid expenses and other	3,538				2,370
Total current assets	96,372				86,508
Oil and natural gas properties on the full cost method:
Proved properties	5,901,661				5,712,813
Unproved properties not being amortized	332,886				296,764
Drilling equipment	1,632,540				1,593,611
Gas gathering and processing equipment	0				0
Saltwater disposal systems	67,074				62,618
Corporate land and building	59,081				59,080
Transportation equipment	16,766				17,423
Other	28,244				25,400
Property, plant, and equipment, gross	8,038,252				7,767,709
Less accumulated depreciation, depletion, amortization, and impairment	5,945,762				5,807,757
Net property and equipment	2,092,490				1,959,952
Intercompany receivable	0				0
Goodwill	62,808				62,808
Investments	1,500				1,500
Other assets	6,186				6,328
Total assets	2,259,356				2,117,096
Current liabilities:
Accounts payable	90,543				81,334
Accrued liabilities	26,583				19,134
Income taxes payable	0
Current derivative liability	0				0
Current portion of other long-term liabilities	6,348				8,501
Total current liabilities	123,474				108,969
Intercompany debt	906,296				870,582
Long-term debt					0
Bonds payable less debt issuance costs	0				0
Non-current derivative liability	0
Other long-term liabilities	72,494				77,566
Deferred income taxes	110,257				85,443
Shareholders' equity:
Preferred stock, $1.00 par value, 5,000,000 shares authorized, none issued	0				0
Common stock, $.20 par value, 175,000,000 shares authorized	0				0
Capital in excess of par value	45,921				45,921
Contributions from Unit	0				0
Accumulated other comprehensive income (loss)	(103)				63
Retained earnings	1,001,017				928,552
Total shareholders’ equity attributable to Unit Corporation	1,046,835				974,536
Non-controlling interests in consolidated subsidiaries	0				0
Total shareholders' equity	1,046,835				974,536
Total liabilities and shareholders' equity	2,259,356				2,117,096
Combined Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	9,039				0	$ 0		$ 0
Accounts receivable, net of allowance for doubtful accounts	28,671				27,916
Materials and supplies	0				0
Current derivative asset	0				0
Prepaid expenses and other	2,756				877
Total current assets	40,466				28,793
Oil and natural gas properties on the full cost method:
Proved properties	0				0
Unproved properties not being amortized	0				0
Drilling equipment	0				0
Gas gathering and processing equipment	751,715				726,236
Saltwater disposal systems	0				0
Corporate land and building	0				0
Transportation equipment	3,064				2,938
Other	0				0
Property, plant, and equipment, gross	754,779				729,174
Less accumulated depreciation, depletion, amortization, and impairment	353,476				322,425
Net property and equipment	401,303				406,749
Intercompany receivable	0				0
Goodwill	0				0
Investments	0				0
Other assets	15,412				3,029
Total assets	457,181				438,571
Current liabilities:
Accounts payable	24,893				18,190
Accrued liabilities	4,716				3,224
Income taxes payable	0
Current derivative liability	0				0
Current portion of other long-term liabilities	6,836				3,844
Total current liabilities	36,445				25,258
Intercompany debt	1,086				285,143
Long-term debt					0
Bonds payable less debt issuance costs	0				0
Non-current derivative liability	0
Other long-term liabilities	16,126				11,380
Deferred income taxes	0				46,554
Shareholders' equity:
Preferred stock, $1.00 par value, 5,000,000 shares authorized, none issued	0				0
Common stock, $.20 par value, 175,000,000 shares authorized	0				0
Capital in excess of par value	197,042				15,549
Contributions from Unit	525				0
Accumulated other comprehensive income (loss)	0				0
Retained earnings	4,329				54,687
Total shareholders’ equity attributable to Unit Corporation	201,896				70,236
Non-controlling interests in consolidated subsidiaries	201,628				0
Total shareholders' equity	403,524				70,236
Total liabilities and shareholders' equity	$ 457,181				$ 438,571

[1] Unit Corporation's consolidated total assets as of September 30, 2018 include total current and long-term assets of its variable interest entity (VIE) (Superior Pipeline Company, L.L.C.) of $41.8 million and $416.7 million, respectively, which can only be used to settle obligations of the VIE. Unit Corporation's consolidated total liabilities as of September 30, 2018 include total current and long-term liabilities of the VIE of $38.6 million and $16.1 million, respectively, for which the creditors of the VIE have no recourse to Unit Corporation. See Note 13 – Variable Interest Entity Arrangements.