Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash provided (required) by operating activities:
Net income	$ 134.2	$ 371.1	$ 14.0
Adjustments to reconcile net income to cash provided (required) by operating activities:
Depreciation	370.2	283.2	315.3
Amortization	244.5	17.5	23.4
Employee benefit plan and share-based compensation costs	18.7	27.4	57.2
Deferred income tax provision (benefit), net	141.6	(172.1)	(64.1)
Unrealized loss (gain) on derivative instruments and foreign exchange	(73.5)	(123.2)	(30.2)
Impairments (Note 5)	34.3	38.2	45.2
Income from equity affiliates, net of dividends received	(37.9)	(48.1)	(26.3)
Other	4.7	161.8	140.1
Changes in operating assets and liabilities, net of effects of acquisitions:
Trade receivables, net and costs in excess of billings	286.8	(268.7)	232.7
Inventories, net	130.9	172.7	(128.3)
Accounts payable, trade	(525.8)	115.5	125.6
Billings in excess of costs	(1,111.4)	(498.3)	(408.2)
Income taxes payable (receivable), net	(152.2)	71.7	8.8
Other assets and liabilities, net	745.6	345.1	395.1
Cash provided (required) by operating activities	210.7	493.8	700.3
Cash provided (required) by investing activities:
Capital expenditures	(255.7)	(312.9)	(325.5)
Cash acquired in merger of FMC Technologies, Inc. and Technip S.A. (Note 2)	1,479.2	0.0	0.0
Cash acquired upon consolidation of investee	0.0	3,480.7	0.0
Cash divested from deconsolidation	0.0	(89.1)	0.0
Proceeds from sale of assets	14.4	39.2	27.1
Other	12.1	(7.4)	(36.7)
Cash provided (required) by investing activities	1,250.0	3,110.5	(335.1)
Cash provided (required) by financing activities:
Net increase (decrease) in short-term debt	(106.4)	8.6	12.0
Net increase (decrease) in commercial paper	234.9	0.0	48.8
Proceeds from issuance of long-term debt	25.7	644.5	31.5
Repayments of long-term debt	(888.0)	(891.2)	(219.1)
Purchase of treasury stock	(58.5)	(186.8)	0.0
Dividends paid	(60.6)	(111.5)	(98.7)
Payments related to taxes withheld on share-based compensation	(46.6)	0.0	0.0
Settlements of mandatorily redeemable financial liability	(156.5)	0.0	0.0
Other	1.2	1.8	98.3
Cash provided (required) by financing activities	(1,054.8)	(534.6)	(127.2)
Effect of changes in foreign exchange rates on cash and cash equivalents	62.2	21.6	(320.6)
Increase (decrease) in cash and cash equivalents	468.1	3,091.3	(82.6)
Cash and cash equivalents, beginning of year	6,269.3	3,178.0	3,260.6
Cash and cash equivalents, end of year	6,737.4	6,269.3	3,178.0
Supplemental disclosures of cash flow information:
Cash paid for interest (net of interest capitalized)	50.3	40.2	61.0
Cash paid for income taxes (net of refunds received)	$ 424.7	$ 261.3	$ 188.4