Guarantor Financial Statements (Unaudited) Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Cash flow from operating activities:
Net (loss) income	$ (3,790)	$ 704	$ (7,995)	$ 1,990
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization	888	945	2,717	2,924
Impairment of oil and gas properties	3,652	308	9,442	308
Net (gains) losses on crude oil and natural gas derivative contracts			(87)	56
Net gain (loss) on early extinguishment of debt	0	(58)	0	(63)
Equity in losses (earnings) of consolidated subsidiaries			1	0
Other, net			(1,812)	(3)
Changes in working capital and other tax payments			342	(699)
Net cash provided by operating activities			2,608	4,513
Cash flow from investing activities:
Capital expenditures	(1,527)	(1,853)	(5,055)	(5,415)
Acquisitions of Deepwater Gulf of Mexico interests			0	(1,421)
Intercompany loans			0	0
Dividends from (investments in) consolidated subsidiaries			(2)	0
Net proceeds from sale of Eagle Ford shale assets			0	2,971
Other, net			116	221
Net cash used in investing activities			(4,941)	(3,644)
Cash flow from financing activities:
Proceeds from debt			6,552	3,346
Repayments of debt			(4,693)	(4,196)
Intercompany loans			0	0
Net proceeds from sale of common Stock			999	0
Cash dividends and distributions paid, and contributions received			(636)	(1,344)
Other, net			(15)	(2)
Net cash provided by (used in) financing activities			2,207	(2,196)
Net decrease in cash and cash equivalents			(126)	(1,327)
Cash and cash equivalents at beginning of year			464	1,985
Cash and cash equivalents at end of period	338	658	338	658
FCX Issuer [Member]
Cash flow from operating activities:
Net (loss) income	(3,830)	552	(8,155)	1,544
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization			3	3
Impairment of oil and gas properties			0	0
Net (gains) losses on crude oil and natural gas derivative contracts			0	0
Net gain (loss) on early extinguishment of debt		0		1
Equity in losses (earnings) of consolidated subsidiaries			5,967	(1,754)
Other, net			(1,953)	87
Changes in working capital and other tax payments			4,001	(217)
Net cash provided by operating activities			(137)	(336)
Cash flow from investing activities:
Capital expenditures			(7)	0
Acquisitions of Deepwater Gulf of Mexico interests				0
Intercompany loans			(1,310)	1,151
Dividends from (investments in) consolidated subsidiaries			693	(959)
Net proceeds from sale of Eagle Ford shale assets				0
Other, net			(21)	0
Net cash used in investing activities			(645)	192
Cash flow from financing activities:
Proceeds from debt			3,893	2,806
Repayments of debt			(3,550)	(1,686)
Intercompany loans			0	0
Net proceeds from sale of common Stock			999
Cash dividends and distributions paid, and contributions received			(547)	(979)
Other, net			(13)	3
Net cash provided by (used in) financing activities			782	144
Net decrease in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of year			0	0
Cash and cash equivalents at end of period	0	0	0	0
FM O&G LLC Guarantor [Member]
Cash flow from operating activities:
Net (loss) income	(3,240)	(249)	(8,920)	111
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization			303	673
Impairment of oil and gas properties	1,658	625	3,710	625
Net (gains) losses on crude oil and natural gas derivative contracts			(87)	56
Net gain (loss) on early extinguishment of debt		(58)		(64)
Equity in losses (earnings) of consolidated subsidiaries			6,516	(637)
Other, net			2	(17)
Changes in working capital and other tax payments			(1,213)	(1,166)
Net cash provided by operating activities			311	(419)
Cash flow from investing activities:
Capital expenditures			(959)	(1,771)
Acquisitions of Deepwater Gulf of Mexico interests				0
Intercompany loans			(955)	734
Dividends from (investments in) consolidated subsidiaries			(49)	(97)
Net proceeds from sale of Eagle Ford shale assets				2,971
Other, net			(2)	32
Net cash used in investing activities			(1,965)	1,869
Cash flow from financing activities:
Proceeds from debt			0	0
Repayments of debt			0	(1,996)
Intercompany loans			1,708	213
Net proceeds from sale of common Stock			0
Cash dividends and distributions paid, and contributions received			(17)	336
Other, net			(37)	(2)
Net cash provided by (used in) financing activities			1,654	(1,449)
Net decrease in cash and cash equivalents			0	1
Cash and cash equivalents at beginning of year			1	0
Cash and cash equivalents at end of period	1	1	1	1
Non-Guarantor Subsidiaries [Member]
Cash flow from operating activities:
Net (loss) income	(3,846)	1,070	(12,364)	2,744
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization			2,474	2,269
Impairment of oil and gas properties	1,967		5,684	0
Net (gains) losses on crude oil and natural gas derivative contracts			0	0
Net gain (loss) on early extinguishment of debt		0		0
Equity in losses (earnings) of consolidated subsidiaries			8,947	4
Other, net			139	(73)
Changes in working capital and other tax payments			(2,457)	684
Net cash provided by operating activities			2,423	5,628
Cash flow from investing activities:
Capital expenditures			(4,079)	(3,644)
Acquisitions of Deepwater Gulf of Mexico interests				(1,421)
Intercompany loans			0	0
Dividends from (investments in) consolidated subsidiaries			102	(696)
Net proceeds from sale of Eagle Ford shale assets				0
Other, net			118	189
Net cash used in investing activities			(3,859)	(5,572)
Cash flow from financing activities:
Proceeds from debt			2,659	540
Repayments of debt			(1,143)	(514)
Intercompany loans			557	(2,098)
Net proceeds from sale of common Stock			0
Cash dividends and distributions paid, and contributions received			(749)	691
Other, net			(14)	(3)
Net cash provided by (used in) financing activities			1,310	(1,384)
Net decrease in cash and cash equivalents			(126)	(1,328)
Cash and cash equivalents at beginning of year			463	1,985
Cash and cash equivalents at end of period	337	657	337	657
Eliminations [Member]
Cash flow from operating activities:
Net (loss) income	7,126	(669)	21,444	(2,409)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, depletion and amortization			(63)	(21)
Impairment of oil and gas properties		(317)	48	(317)
Net (gains) losses on crude oil and natural gas derivative contracts			0	0
Net gain (loss) on early extinguishment of debt		0		0
Equity in losses (earnings) of consolidated subsidiaries			(21,429)	2,387
Other, net			0	0
Changes in working capital and other tax payments			11	0
Net cash provided by operating activities			11	(360)
Cash flow from investing activities:
Capital expenditures			(10)	0
Acquisitions of Deepwater Gulf of Mexico interests				0
Intercompany loans			2,265	(1,885)
Dividends from (investments in) consolidated subsidiaries			(748)	1,752
Net proceeds from sale of Eagle Ford shale assets				0
Other, net			21	0
Net cash used in investing activities			1,528	(133)
Cash flow from financing activities:
Proceeds from debt			0	0
Repayments of debt			0	0
Intercompany loans			(2,265)	1,885
Net proceeds from sale of common Stock			0
Cash dividends and distributions paid, and contributions received			677	(1,392)
Other, net			49	0
Net cash provided by (used in) financing activities			(1,539)	493
Net decrease in cash and cash equivalents			0	0
Cash and cash equivalents at beginning of year			0	0
Cash and cash equivalents at end of period	$ 0	$ 0	$ 0	$ 0