Guarantor Financial Statements (Unaudited) Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Jan. 05, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ (410)	$ (1,799)	$ (4,511)	$ (4,205)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				1,374	1,829
Impairment of oil and gas properties		291	2,686	4,078	5,790
Net gains on crude oil derivative contracts				0	(58)
Equity in losses (earnings) of consolidated subsidiaries				(8)	(1)
Other, net				215	(1,379)
Changes in working capital and other tax payments, excluding amounts from dispositions				466	(190)
Net cash provided by operating activities				1,614	1,786
Cash flow from investing activities:
Capital expenditures		(833)	(1,661)	(1,815)	(3,528)
Intercompany loans				0	0
Dividends from (investments in) consolidated subsidiaries				0	0
Asset sales and other, net				1,280	136
Net cash provided by (used in) investing activities				(535)	(3,392)
Cash flow from financing activities:
Proceeds from debt				2,811	4,422
Repayments of debt				(3,649)	(2,360)
Intercompany loans				0	0
Net proceeds from sale of common stock	$ 1,970			32	0
Cash dividends and distributions paid, and contributions received, net				(44)	(440)
Other, net				(23)	(14)
Net cash (used in) provided by financing activities				(873)	1,608
Net increase in cash and cash equivalents				206	2
Increase in cash and cash equivalents in assets held for sale				(49)	(1)
Cash and cash equivalents at beginning of year	195			195	317
Cash and cash equivalents at end of period		352	318	352	318
FCX Issuer [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		(481)	(1,851)	(4,664)	(4,325)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				3	2
Impairment of oil and gas properties				0	0
Net gains on crude oil derivative contracts					0
Equity in losses (earnings) of consolidated subsidiaries				2,375	3,524
Other, net				104	(1,431)
Changes in working capital and other tax payments, excluding amounts from dispositions				2,009	2,222
Net cash provided by operating activities				(173)	(8)
Cash flow from investing activities:
Capital expenditures				0	0
Intercompany loans				(994)	(1,073)
Dividends from (investments in) consolidated subsidiaries				1,935	438
Asset sales and other, net				0	(10)
Net cash provided by (used in) investing activities				941	(645)
Cash flow from financing activities:
Proceeds from debt				1,505	2,735
Repayments of debt				(2,282)	(1,690)
Intercompany loans				0	0
Net proceeds from sale of common stock				32
Cash dividends and distributions paid, and contributions received, net				(5)	(380)
Other, net				(18)	(12)
Net cash (used in) provided by financing activities				(768)	653
Net increase in cash and cash equivalents				0	0
Increase in cash and cash equivalents in assets held for sale				0	0
Cash and cash equivalents at beginning of year	0			0	0
Cash and cash equivalents at end of period		0	0	0	0
FM O&G LLC Guarantor [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		(847)	(2,596)	(4,490)	(5,680)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				92	223
Impairment of oil and gas properties		200	1,000	1,436	2,052
Net gains on crude oil derivative contracts					(58)
Equity in losses (earnings) of consolidated subsidiaries				2,985	4,279
Other, net				600	9
Changes in working capital and other tax payments, excluding amounts from dispositions				(713)	(550)
Net cash provided by operating activities				(90)	275
Cash flow from investing activities:
Capital expenditures				(433)	(734)
Intercompany loans				(493)	(794)
Dividends from (investments in) consolidated subsidiaries				(41)	(31)
Asset sales and other, net				91	(1)
Net cash provided by (used in) investing activities				(876)	(1,560)
Cash flow from financing activities:
Proceeds from debt				0	0
Repayments of debt				0	0
Intercompany loans				1,018	1,321
Net proceeds from sale of common stock				0
Cash dividends and distributions paid, and contributions received, net				0	0
Other, net				(52)	(37)
Net cash (used in) provided by financing activities				966	1,284
Net increase in cash and cash equivalents				0	(1)
Increase in cash and cash equivalents in assets held for sale				0	0
Cash and cash equivalents at beginning of year	0			0	1
Cash and cash equivalents at end of period		0	0	0	0
Non-Guarantor Subsidiaries [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		(300)	(3,819)	(5,198)	(8,518)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				1,293	1,638
Impairment of oil and gas properties		100	1,700	2,622	3,717
Net gains on crude oil derivative contracts					0
Equity in losses (earnings) of consolidated subsidiaries				4,483	6,502
Other, net				(489)	43
Changes in working capital and other tax payments, excluding amounts from dispositions				(836)	(1,870)
Net cash provided by operating activities				1,875	1,512
Cash flow from investing activities:
Capital expenditures				(1,380)	(2,787)
Intercompany loans				0	0
Dividends from (investments in) consolidated subsidiaries				78	74
Asset sales and other, net				1,189	137
Net cash provided by (used in) investing activities				(113)	(2,576)
Cash flow from financing activities:
Proceeds from debt				1,306	1,687
Repayments of debt				(1,367)	(670)
Intercompany loans				469	546
Net proceeds from sale of common stock				42
Cash dividends and distributions paid, and contributions received, net				(1,989)	(481)
Other, net				(17)	(15)
Net cash (used in) provided by financing activities				(1,556)	1,067
Net increase in cash and cash equivalents				206	3
Increase in cash and cash equivalents in assets held for sale				(49)	(1)
Cash and cash equivalents at beginning of year	195			195	316
Cash and cash equivalents at end of period		352	318	352	318
Consolidation, Eliminations [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		1,218	6,467	9,841	14,318
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				(14)	(34)
Impairment of oil and gas properties				20	21
Net gains on crude oil derivative contracts					0
Equity in losses (earnings) of consolidated subsidiaries				(9,851)	(14,306)
Other, net				0	0
Changes in working capital and other tax payments, excluding amounts from dispositions				6	8
Net cash provided by operating activities				2	7
Cash flow from investing activities:
Capital expenditures				(2)	(7)
Intercompany loans				1,487	1,867
Dividends from (investments in) consolidated subsidiaries				(1,972)	(481)
Asset sales and other, net				0	10
Net cash provided by (used in) investing activities				(487)	1,389
Cash flow from financing activities:
Proceeds from debt				0	0
Repayments of debt				0	0
Intercompany loans				(1,487)	(1,867)
Net proceeds from sale of common stock				(42)
Cash dividends and distributions paid, and contributions received, net				1,950	421
Other, net				64	50
Net cash (used in) provided by financing activities				485	(1,396)
Net increase in cash and cash equivalents				0	0
Increase in cash and cash equivalents in assets held for sale				0	0
Cash and cash equivalents at beginning of year	$ 0			0	0
Cash and cash equivalents at end of period		$ 0	$ 0	$ 0	$ 0