| Document and Entity Information | 9 Months Ended |
| Sep. 30, 2013 | |
| Document And Entity Information [Abstract] | ' |
| Document Type | '10-Q |
| Amendment Flag | 'false |
| Document Period End Date | 30-Sep-13 |
| Document Fiscal Year Focus | '2013 |
| Document Fiscal Period Focus | 'Q3 |
| Trading Symbol | 'AOIP |
| Entity Registrant Name | 'APACHE OFFSHORE INVESTMENT PARTNERSHIP |
| Entity Central Index Key | '0000727538 |
| Current Fiscal Year End Date | '--12-31 |
| Entity Filer Category | 'Smaller Reporting Company |
| Entity Common Stock, Shares Outstanding | 1,022 |
| Statement of Consolidated Income (USD $) | 3 Months Ended | 9 Months Ended | ||
| Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | |
| REVENUES: | ' | ' | ' | ' |
| Oil and gas sales | $876,321 | $1,037,358 | $2,849,505 | $3,346,560 |
| Interest income | 46 | ' | 74 | 6 |
| Total Revenues | 876,367 | 1,037,358 | 2,849,579 | 3,346,566 |
| EXPENSES: | ' | ' | ' | ' |
| Depreciation, depletion and amortization | 178,827 | 221,370 | 592,737 | 688,935 |
| Asset retirement obligation accretion | 27,205 | 30,748 | 90,709 | 90,902 |
| Lease operating expenses | 278,193 | 365,303 | 970,754 | 1,002,309 |
| Gathering and transportation costs | 26,964 | 29,135 | 81,739 | 109,955 |
| Administrative | 90,500 | 99,250 | 286,500 | 297,750 |
| Total Expenses | 601,689 | 745,806 | 2,022,439 | 2,189,851 |
| NET INCOME | 274,678 | 291,552 | 827,140 | 1,156,715 |
| NET INCOME ALLOCATED TO: | ' | ' | ' | ' |
| Managing Partner | 87,683 | 99,034 | 274,065 | 357,531 |
| Investing Partners | 186,995 | 192,518 | 553,075 | 799,184 |
| NET INCOME | $274,678 | $291,552 | $827,140 | $1,156,715 |
| NET INCOME PER INVESTING PARTNER UNIT | $183 | $188 | $541 | $782 |
| WEIGHTED AVERAGE INVESTING PARTNER UNITS OUTSTANDING | 1,021.50 | 1,021.50 | 1,021.50 | 1,021.50 |
| Statement of Consolidated Cash Flows (USD $) | 9 Months Ended | |
| Sep. 30, 2013 | Sep. 30, 2012 | |
| CASH FLOWS FROM OPERATING ACTIVITIES: | ' | ' |
| Net income | $827,140 | $1,156,715 |
| Adjustments to reconcile net income to net cash provided by operating activities: | ' | ' |
| Depreciation, depletion and amortization | 592,737 | 688,935 |
| Asset retirement obligation accretion | 90,709 | 90,902 |
| Changes in operating assets and liabilities: | ' | ' |
| (Increase) decrease in accrued receivables | 76,872 | 186,440 |
| Increase (decrease) in receivable from/payable to Apache Corporation | -73,764 | -188,630 |
| Increase (decrease) in accrued operating expenses | 929 | -278,164 |
| Increase (decrease) in deferred credits and other | -236,073 | ' |
| Net cash provided by operating activities | 1,278,550 | 1,656,198 |
| CASH FLOWS FROM INVESTING ACTIVITIES: | ' | ' |
| Additions to oil and gas properties | -14,320 | -37,428 |
| Net cash used in investing activities | -14,320 | -37,428 |
| CASH FLOWS FROM FINANCING ACTIVITIES: | ' | ' |
| Distributions to Managing Partner | -296,953 | -422,130 |
| Net cash used in financing activities | -296,953 | -422,130 |
| NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS | 967,277 | 1,196,640 |
| CASH AND CASH EQUIVALENTS, BEGINNING OF YEAR | 3,118,789 | 1,404,394 |
| CASH AND CASH EQUIVALENTS, END OF PERIOD | $4,086,066 | $2,601,034 |
| Consolidated Balance Sheet (USD $) | Sep. 30, 2013 | Dec. 31, 2012 |
| CURRENT ASSETS: | ' | ' |
| Cash and cash equivalents | $4,086,066 | $3,118,789 |
| Accrued revenues receivable | 41,975 | 118,847 |
| Total Current Assets | 4,128,041 | 3,237,636 |
| OIL AND GAS PROPERTIES, on the basis of full cost accounting: | ' | ' |
| Proved properties | 194,642,926 | 194,451,931 |
| Less - Accumulated depreciation, depletion and amortization | -186,064,695 | -185,471,958 |
| Total oil and gas properties, on the basis of full cost accounting | 8,578,231 | 8,979,973 |
| Total Assets | 12,706,272 | 12,217,609 |
| CURRENT LIABILITIES: | ' | ' |
| Payable to Apache Corporation | 1,257 | 75,021 |
| Current asset retirement obligation | 343,711 | ' |
| Accrued operating expenses | 125,286 | 124,357 |
| Accrued development costs | ' | 35,978 |
| Total Current Liabilities | 470,254 | 235,356 |
| ASSET RETIREMENT OBLIGATION | 1,885,385 | 2,161,807 |
| PARTNERS' CAPITAL: | ' | ' |
| Managing Partner | 419,917 | 442,805 |
| Investing Partners (1,021.5 units outstanding) | 9,930,716 | 9,377,641 |
| Total Partners' Capital | 10,350,633 | 9,820,446 |
| Total liabilities and partners' capital | $12,706,272 | $12,217,609 |
| Consolidated Balance Sheet (Parenthetical) | Sep. 30, 2013 | Dec. 31, 2012 |
| Statement Of Financial Position [Abstract] | ' | ' |
| Investing Partners, units outstanding | 1,021.50 | 1,021.50 |
| SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES | 9 Months Ended |
| Sep. 30, 2013 | |
| Accounting Policies [Abstract] | ' |
| SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES | ' |
| 1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES | |
| As of September 30, 2013, the Partnership’s significant accounting policies are consistent with those discussed in Note 2 of its consolidated financial statements contained in the Annual Report on Form 10-K for the fiscal year ended December 31, 2012. | |
| Use of Estimates | |
| The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates with regard to these financial statements include the estimate of proved oil and gas reserves and related present value estimates of future net cash flow therefrom and asset retirement obligations. Actual results could differ from those estimates. |
| RECEIVABLE FROM / PAYABLE TO APACHE CORPORATION | 9 Months Ended |
| Sep. 30, 2013 | |
| Related Party Transactions [Abstract] | ' |
| RECEIVABLE FROM / PAYABLE TO APACHE CORPORATION | ' |
| 2. RECEIVABLE FROM / PAYABLE TO APACHE CORPORATION | |
| The receivable from/payable to Apache represents the net result of the Investing Partners’ revenue and expenditure transactions in the current month. Generally, cash in this amount will be paid by Apache to the Partnership or transferred to Apache in the month after the Partnership’s transactions are processed and the net results of operations are determined. |
| RIGHT OF PRESENTMENT | 9 Months Ended | |
| Sep. 30, 2013 | ||
| Equity [Abstract] | ' | |
| RIGHT OF PRESENTMENT | ' | |
| 3 | RIGHT OF PRESENTMENT | |
| As provided in the Partnership Agreement, as amended (the “Amended Partnership Agreement”), a first right of presentment valuation was computed during the first quarter of 2013. The per-unit value was determined to be $15,412 based on the valuation date of December 31, 2012. A second right of presentment valuation was computed during October 2013 and the per-unit value was determined to be $15,622 based on a valuation date of June 30, 2013. The Partnership did not repurchase any Investing Partner Units (Units) during the first nine months of 2013, as a result of the Partnership’s limited amount of cash available for discretionary purposes, and is not expected to purchase any Units in the fourth quarter of 2013. The per-unit right of presentment value computed during the first quarter of 2012 was determined to be $15,516 based on the valuation date of December 31, 2011, and the second per-unit right of presentment in 2012 was $15,932 based on a valuation date of June 30, 2012. The Partnership did not repurchase any Units during the first nine months of 2012. Pursuant to the Amended Partnership Agreement, the Partnership has no obligation to purchase any Units presented to the extent it determines that it has insufficient funds for such purchases. | ||
| ASSET RETIREMENT OBLIGATIONS | 9 Months Ended | ||||
| Sep. 30, 2013 | |||||
| Asset Retirement Obligation Disclosure [Abstract] | ' | ||||
| ASSET RETIREMENT OBLIGATIONS | ' | ||||
| 4. ASSET RETIREMENT OBLIGATIONS | |||||
| The following table describes the changes to the Partnership’s asset retirement obligation liability for the first nine months of 2013: | |||||
| Asset retirement obligation at December 31, 2012 | $ | 2,161,807 | |||
| Accretion expense | 90,709 | ||||
| Liabilities settled | (200,095 | ) | |||
| Revisions in estimated liabilities | 176,675 | ||||
| Asset retirement obligation at September 30, 2013 | 2,229,096 | ||||
| Less current portion | (343,711 | ) | |||
| Asset retirement obligation, long-term | $ | 1,885,385 | |||
| FAIR VALUE MEASUREMENTS | 9 Months Ended |
| Sep. 30, 2013 | |
| Fair Value Disclosures [Abstract] | ' |
| FAIR VALUE MEASUREMENTS | ' |
| 5. FAIR VALUE MEASUREMENTS | |
| Certain assets and liabilities are reported at fair value on a recurring basis in the Partnership’s consolidated balance sheet. As of September 30, 2013, and December 31, 2012, the carrying amounts of the Partnership’s current assets and current liabilities approximated fair value because of the short-term nature or maturity of these instruments. | |
| The Partnership did not use derivative financial instruments or otherwise engage in hedging activities during the nine months ended September 30, 2013, and 2012. |
| SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies) | 9 Months Ended |
| Sep. 30, 2013 | |
| Accounting Policies [Abstract] | ' |
| Use of Estimates | ' |
| Use of Estimates | |
| The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Significant estimates with regard to these financial statements include the estimate of proved oil and gas reserves and related present value estimates of future net cash flow therefrom and asset retirement obligations. Actual results could differ from those estimates. |
| ASSET RETIREMENT OBLIGATIONS (Tables) | 9 Months Ended | ||||
| Sep. 30, 2013 | |||||
| Asset Retirement Obligation Disclosure [Abstract] | ' | ||||
| Changes to Partnership's Asset Retirement Obligation Liability | ' | ||||
| The following table describes the changes to the Partnership’s asset retirement obligation liability for the first nine months of 2013: | |||||
| Asset retirement obligation at December 31, 2012 | $ | 2,161,807 | |||
| Accretion expense | 90,709 | ||||
| Liabilities settled | (200,095 | ) | |||
| Revisions in estimated liabilities | 176,675 | ||||
| Asset retirement obligation at September 30, 2013 | 2,229,096 | ||||
| Less current portion | (343,711 | ) | |||
| Asset retirement obligation, long-term | $ | 1,885,385 | |||
| Right of Presentment - Additional Information (Detail) | Jun. 30, 2013 | Dec. 31, 2012 | Jun. 30, 2012 | Mar. 31, 2012 |
| Equity [Abstract] | ' | ' | ' | ' |
| Investing partner units value per unit | 15,622 | 15,412 | 15,932 | 15,516 |
| Asset Retirement Obligations - Changes to Partnership's Asset Retirement Obligation Liability (Detail) (USD $) | 3 Months Ended | 9 Months Ended | |||
| Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Dec. 31, 2012 | |
| Asset Retirement Obligation Disclosure [Abstract] | ' | ' | ' | ' | ' |
| Asset retirement obligation | ' | ' | $2,161,807 | ' | ' |
| Accretion expense | 27,205 | 30,748 | 90,709 | 90,902 | ' |
| Liabilities settled | ' | ' | -200,095 | ' | ' |
| Revisions in estimated liabilities | ' | ' | 176,675 | ' | ' |
| Asset retirement obligation | 2,229,096 | ' | 2,229,096 | ' | ' |
| Less current portion | -343,711 | ' | -343,711 | ' | ' |
| Asset retirement obligation, long-term | $1,885,385 | ' | $1,885,385 | ' | $2,161,807 |
