Variable Interest Entity Arrangements (Schedule of Assets and Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018		Jan. 01, 2018	Dec. 31, 2017	Sep. 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
Prepaid expenses and other	9,419			6,233
Total current assets	223,604			119,672
Property and equipment:
Gas gathering and processing equipment	751,715			726,236
Transportation equipment	29,103			29,631
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
Other assets	28,703		$ 27,028	16,230
Total assets	2,820,765	[1]		2,581,452
Current liabilities:
Accounts payable	143,552			112,648
Accrued liabilities	67,743			48,523
Current portion of other long-term liabilities	14,150		15,750	13,002
Total current liabilities	239,563			181,936
Long-term debt less debt issuance costs	643,921			820,276
Other long-term liabilities	101,410		$ 109,940	$ 100,203
VIE [Member]
Current assets:
Cash and cash equivalents	9,039
Accounts receivable, net of allowance for doubtful accounts	29,991
Prepaid expenses and other	2,756
Total current assets	41,786
Property and equipment:
Gas gathering and processing equipment	751,715
Transportation equipment	3,064
Property, plant, and equipment, gross	754,779
Less accumulated depreciation, depletion, amortization, and impairment	353,476
Net property and equipment	401,303
Other assets	15,411
Total assets	458,500
Current liabilities:
Accounts payable	28,183
Accrued liabilities	3,574
Current portion of other long-term liabilities	6,836
Total current liabilities	38,593
Long-term debt less debt issuance costs	0
Other long-term liabilities	16,126
Total liabilities	$ 54,719

[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.