DOMESTIC AND FOREIGN INCOME TAXES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Domestic and foreign components of income from continuing operations before domestic and foreign income taxes
Income from continuing operations before income taxes, Domestic	$ 3,431	$ (609)	$ (2,698)
Income from continuing operations before income taxes, Foreign	2,177	1,937	1,034
Pre-tax operating profit (loss)	5,608	1,328	(1,664)
Provisions (credits) for domestic and foreign income taxes on continuing operations
Current United States Federal tax expense (benefit)	(23)	(81)	(784)
Current State and Local tax expense (benefit)	52	11	9
Current Foreign tax expense (benefit)	1,077	806	630
Current Total tax expense (benefit)	1,106	736	(145)
Deferred United States Federal tax expense (benefit)	422	(856)	(504)
Deferred State and Local tax expense (benefit)	12	23	(19)
Deferred Foreign tax expense (benefit)	(63)	114	6
Deferred Total tax expense (benefit)	371	(719)	(517)
United States Federal Total tax expense (benefit)	399	(937)	(1,288)
State and Local Total tax expense (benefit)	64	34	(10)
Foreign Total tax expense (benefit)	1,014	920	636
Total tax expense (benefit)	$ 1,477	$ 17	$ (662)
Reconciliation of the United States federal statutory income tax rate to Occidental's worldwide effective tax rate on income from continuing operations
United States federal statutory tax rate	21.00%	35.00%	35.00%
Other than temporary loss on available for sale investment in California Resources stock	0.00%	0.00%	(2.00%)
Enhanced oil recovery credit	(3.00%)	(9.00%)	5.00%
Tax benefit due to write off of exploration blocks	0.00%	0.00%	14.00%
Change in federal income tax rate	0.00%	(44.00%)	0.00%
Tax (benefit) expense due to reversal of indefinite reinvestment assertion	(2.00%)	7.00%	0.00%
Operations outside the United States	11.00%	12.00%	(14.00%)
State income taxes, net of federal benefit	1.00%	2.00%	0.00%
Other	(2.00%)	(2.00%)	2.00%
Worldwide effective tax rate	26.00%	1.00%	40.00%
Tax Cuts and Jobs Act (TCJA)
Estimate of state tax associated with mandatory deemed repatriation	$ 25
Deferred Tax Assets
Environmental reserves	195	$ 191
Postretirement benefit accruals	176	145
Deferred compensation and benefits	170	151
Asset retirement obligations	280	228
Foreign tax credit carryforwards	2,356	2,750
General business credit carryforwards	429	407
Net operating loss carryforward	29	437
Federal benefit of state income taxes	18	10
All other	93	146
Subtotal	3,746	4,465
Valuation allowance	(2,403)	(2,640)
Total deferred taxes	1,343	1,825
Deferred Tax Liabilities
Property, plant and equipment differences	2,089	2,272
Equity investments, partnerships and foreign subsidiaries	161	134
Deferred Tax Liabilities, total deferred taxes	2,250	2,406
Deferred tax assets	1,343	1,825
Foreign tax credit carryforwards	2,356	2,750
State operating loss carryforwards	28
State tax credit carryforward	41
Federal operating loss carryforwards that expire in 2037	14
Deferred tax liability released	99
Deferred foreign tax liability due to reversal of indefinite re-investment assertion	837
Additional deferred tax liability amount required	199
Discontinued operations income tax charges (benefits)			$ 249
Reconciliation of unrecognized tax benefits
Balance, at beginning of period	22	22	22
Reductions based on tax positions related to prior years and settlements	(22)	0	0
Balance, at end of period	0	22	$ 22
State
Deferred Tax Liabilities
Valuation allowance on net operating loss carryforwards	33
Other current assets
Reconciliation of unrecognized tax benefits
Income tax receivables	68	76
Long-term receivables and other assets, net
Reconciliation of unrecognized tax benefits
Federal alternative minimum tax non-current receivables	$ 68	$ 221