Guarantor Financial Statements (Unaudited) Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jan. 05, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 286	$ (3,790)	$ (4,225)	$ (7,995)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				2,017	2,717
Impairment of oil and gas properties		239	3,652	4,317	9,442
Net gains on crude oil derivative contracts				0	(87)
Equity in losses (earnings) of consolidated subsidiaries				(9)	1
Other, net				31	(1,812)
Changes in working capital and other tax payments, excluding amounts from dispositions				463	342
Net cash provided by operating activities				2,594	2,608
Cash flow from investing activities:
Capital expenditures		(494)	(1,527)	(2,309)	(5,055)
Intercompany loans				0	0
Dividends from (investments in) consolidated subsidiaries				0	(2)
Asset sales and other, net				1,415	116
Net cash provided by (used in) investing activities				(894)	(4,941)
Cash flow from financing activities:
Proceeds from debt				3,463	6,552
Repayments of debt				(4,539)	(4,693)
Intercompany loans				0	0
Net proceeds from sale of common stock	$ 1,970	411		442	999
Cash dividends and distributions paid, and contributions received, net				(92)	(636)
Other, net				(22)	(15)
Net cash (used in) provided by financing activities				(748)	2,207
Net increase (decrease) in cash and cash equivalents				952	(126)
(Increase) decrease in cash and cash equivalents in assets held for sale				(39)	42
Cash and cash equivalents at beginning of year	195			195	317
Cash and cash equivalents at end of period		1,108	233	1,108	233
FCX Issuer [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		217	(3,830)	(4,446)	(8,155)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				4	3
Impairment of oil and gas properties				0	0
Net gains on crude oil derivative contracts					0
Equity in losses (earnings) of consolidated subsidiaries				2,450	5,967
Other, net				(116)	(1,953)
Changes in working capital and other tax payments, excluding amounts from dispositions				1,844	4,001
Net cash provided by operating activities				(264)	(137)
Cash flow from investing activities:
Capital expenditures				0	(7)
Intercompany loans				(1,021)	(1,310)
Dividends from (investments in) consolidated subsidiaries				1,643	693
Asset sales and other, net				0	(21)
Net cash provided by (used in) investing activities				622	(645)
Cash flow from financing activities:
Proceeds from debt				1,721	3,893
Repayments of debt				(2,498)	(3,550)
Intercompany loans				0	0
Net proceeds from sale of common stock				442	999
Cash dividends and distributions paid, and contributions received, net				(5)	(547)
Other, net				(18)	(13)
Net cash (used in) provided by financing activities				(358)	782
Net increase (decrease) in cash and cash equivalents				0	0
(Increase) decrease 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		(589)	(3,240)	(5,079)	(8,920)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				146	303
Impairment of oil and gas properties		95	1,700	1,531	3,710
Net gains on crude oil derivative contracts					(87)
Equity in losses (earnings) of consolidated subsidiaries				3,202	6,516
Other, net				575	2
Changes in working capital and other tax payments, excluding amounts from dispositions				(669)	(1,213)
Net cash provided by operating activities				(294)	311
Cash flow from investing activities:
Capital expenditures				(497)	(959)
Intercompany loans				(518)	(955)
Dividends from (investments in) consolidated subsidiaries				(41)	(49)
Asset sales and other, net				208	(2)
Net cash provided by (used in) investing activities				(848)	(1,965)
Cash flow from financing activities:
Proceeds from debt				0	0
Repayments of debt				0	0
Intercompany loans				1,223	1,708
Net proceeds from sale of common stock				0	0
Cash dividends and distributions paid, and contributions received, net				(78)	(17)
Other, net				(2)	(37)
Net cash (used in) provided by financing activities				1,143	1,654
Net increase (decrease) in cash and cash equivalents				1	0
(Increase) decrease 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		1	1	1	1
Non-Guarantor Subsidiaries [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		(233)	(3,846)	(5,430)	(12,364)
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				1,882	2,474
Impairment of oil and gas properties		200	2,000	2,765	5,684
Net gains on crude oil derivative contracts					0
Equity in losses (earnings) of consolidated subsidiaries				5,072	8,947
Other, net				(424)	139
Changes in working capital and other tax payments, excluding amounts from dispositions				(714)	(2,457)
Net cash provided by operating activities				3,151	2,423
Cash flow from investing activities:
Capital expenditures				(1,814)	(4,079)
Intercompany loans				0	0
Dividends from (investments in) consolidated subsidiaries				124	102
Asset sales and other, net				1,210	118
Net cash provided by (used in) investing activities				(480)	(3,859)
Cash flow from financing activities:
Proceeds from debt				1,742	2,659
Repayments of debt				(2,041)	(1,143)
Intercompany loans				316	557
Net proceeds from sale of common stock				374	0
Cash dividends and distributions paid, and contributions received, net				(2,096)	(749)
Other, net				(15)	(14)
Net cash (used in) provided by financing activities				(1,720)	1,310
Net increase (decrease) in cash and cash equivalents				951	(126)
(Increase) decrease in cash and cash equivalents in assets held for sale				(39)	42
Cash and cash equivalents at beginning of year	195			195	316
Cash and cash equivalents at end of period		1,107	232	1,107	232
Consolidation, Eliminations [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		891	7,126	10,730	21,444
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization				(15)	(63)
Impairment of oil and gas properties				21	48
Net gains on crude oil derivative contracts					0
Equity in losses (earnings) of consolidated subsidiaries				(10,733)	(21,429)
Other, net				(4)	0
Changes in working capital and other tax payments, excluding amounts from dispositions				2	11
Net cash provided by operating activities				1	11
Cash flow from investing activities:
Capital expenditures				2	(10)
Intercompany loans				1,539	2,265
Dividends from (investments in) consolidated subsidiaries				(1,726)	(748)
Asset sales and other, net				(3)	21
Net cash provided by (used in) investing activities				(188)	1,528
Cash flow from financing activities:
Proceeds from debt				0	0
Repayments of debt				0	0
Intercompany loans				(1,539)	(2,265)
Net proceeds from sale of common stock				(374)	0
Cash dividends and distributions paid, and contributions received, net				2,087	677
Other, net				13	49
Net cash (used in) provided by financing activities				187	(1,539)
Net increase (decrease) in cash and cash equivalents				0	0
(Increase) decrease 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