Financial Information and Accounting Policies - Adjusted Income Statement and Comprehensive Income to Apply Adopted Guidance (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended												9 Months Ended
		Sep. 30, 2022		Jun. 30, 2022		Mar. 31, 2022		Sep. 30, 2021		Jun. 30, 2021		Mar. 31, 2021		Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Costs of sales and services		$ 899.7						$ 682.5						$ 2,539.1	$ 2,078.4
Gross margin		477.5						511.5						1,641.2	1,553.2
Total costs and expenses		1,166.6						978.3						3,430.5	2,869.1
Income from continuing operations before non-operating pension and postretirement charges (income), interest expense, net and income taxes		210.6						215.7						749.8	762.5
Non-operating pension and postretirement charges (income)		(1.7)						1.5						6.5	3.9
Income (loss) from continuing operations before income taxes		170.5						181.1						636.3	660.5
Provision (benefit) for income taxes		36.0						9.2						133.0	75.8
Income (loss) from continuing operations		134.5						171.9						503.3	584.7
Discontinued operations, net of income taxes		(16.2)						(9.7)						(42.2)	(32.4)
Net income (loss)		118.3		$ 131.2		$ 211.6		162.2		$ 205.0		$ 185.1		461.1	552.3
Net income (loss) attributable to FMC stockholders		$ 121.0						$ 159.7						$ 462.6	$ 548.9
Basic earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)		$ 1.09						$ 1.32						$ 3.99	$ 4.51
Net income (loss) attributable to FMC stockholders		0.96						1.24						3.66	4.26
Diluted earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)		1.08						1.32						3.98	4.48
Net income (loss) attributable to FMC stockholders (in USD per share)		$ 0.95						$ 1.24						$ 3.65	$ 4.23
Less: Net income (loss) attributable to noncontrolling interests		$ (2.7)						$ 2.5						$ (1.5)	$ 3.4
Net income (loss) attributable to FMC stockholders		121.0						159.7						462.6	548.9
Statement of Comprehensive Income [Abstract]
Net income (loss)		118.3		131.2		211.6		162.2		205.0		185.1		461.1	552.3
Pension and other postretirement benefits:
Unrealized actuarial gains (losses) and prior service (costs) credits, net of tax expense (benefit)		(0.1)						(0.7)						(0.1)	(2.2)
Reclassification of net actuarial and other (gain) loss and amortization of prior service costs, included in net income, net of tax (expense) benefit	[1]	0.0						2.5						6.8	6.9
Total pension and other postretirement benefits, net of tax expense (benefit) of $1.2 as computed and zero as reported for the three months ended September 30, 2022		(0.1)	[2]	$ 3.2	[2]	$ 3.6	[2]	1.8	[3]	$ 1.5	[3]	$ 1.4	[3]	6.7	4.7
Other comprehensive income (loss), net of tax		(72.5)						17.2						(218.5)	(10.7)
Comprehensive income (loss)		45.8						179.4						242.6	541.6
Comprehensive income (loss) attributable to FMC stockholders		49.2						177.2						246.1	538.4
Unrealized actuarial gains (losses) and prior service (costs) credits, tax		0.0						(0.2)						0.0	(0.6)
Reclassification of net actuarial and other (gain) loss and amortization of prior service costs, included in net income, tax		0.0						0.7						1.8	1.8
Total pension and other postretirement benefits, tax		0.0						(0.5)						(1.8)	1.2
As Previously Reported
Income Statement [Abstract]
Costs of sales and services								681.2						2,539.1	2,074.6
Gross margin								512.8						1,641.2	1,557.0
Total costs and expenses								977.0						3,430.5	2,865.3
Income from continuing operations before non-operating pension and postretirement charges (income), interest expense, net and income taxes		210.6						217.0						749.8	766.3
Non-operating pension and postretirement charges (income)		3.9						5.1						12.1	14.7
Income (loss) from continuing operations before income taxes		164.9						178.8						630.7	653.5
Provision (benefit) for income taxes		34.8						8.7						131.8	74.3
Income (loss) from continuing operations		130.1						170.1						498.9	579.2
Net income (loss)		113.9						160.4						456.7	546.8
Net income (loss) attributable to FMC stockholders		$ 116.6						$ 157.9						$ 458.2	$ 543.4
Basic earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)		$ 1.05						$ 1.30						$ 3.96	$ 4.46
Net income (loss) attributable to FMC stockholders		0.92						1.22						3.63	4.21
Diluted earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)		1.05						1.30						3.94	4.44
Net income (loss) attributable to FMC stockholders (in USD per share)		$ 0.92						$ 1.22						$ 3.61	$ 4.19
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 113.9						$ 160.4						$ 456.7	$ 546.8
Pension and other postretirement benefits:
Unrealized actuarial gains (losses) and prior service (costs) credits, net of tax expense (benefit)		(0.1)						0.1						(0.1)	0.0
Reclassification of net actuarial and other (gain) loss and amortization of prior service costs, included in net income, net of tax (expense) benefit		4.4						4.5						11.2	13.2
Total pension and other postretirement benefits, net of tax expense (benefit) of $1.2 as computed and zero as reported for the three months ended September 30, 2022		4.3						4.6						11.1	13.2
Other comprehensive income (loss), net of tax		(68.1)						20.0						(214.1)	(2.2)
Comprehensive income (loss)		45.8						180.4						242.6	544.6
Comprehensive income (loss) attributable to FMC stockholders		49.2						178.2						246.1	541.4
Unrealized actuarial gains (losses) and prior service (costs) credits, tax		0.0						0.0							0.0
Reclassification of net actuarial and other (gain) loss and amortization of prior service costs, included in net income, tax		1.2						1.2						2.7	3.5
Total pension and other postretirement benefits, tax		(1.2)						(1.2)						(2.7)	3.5
Effect of Change
Income Statement [Abstract]
Costs of sales and services		0.0												0.0
Gross margin		0.0												0.0
Total costs and expenses		0.0												0.0
Income from continuing operations before non-operating pension and postretirement charges (income), interest expense, net and income taxes		0.0												0.0
Non-operating pension and postretirement charges (income)		(5.6)												(5.6)
Income (loss) from continuing operations before income taxes		5.6												5.6
Provision (benefit) for income taxes		1.2												1.2
Income (loss) from continuing operations		4.4												4.4
Net income (loss)		4.4												4.4
Net income (loss) attributable to FMC stockholders		$ 4.4												$ 4.4
Basic earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)		$ 0.04												$ 0.03
Net income (loss) attributable to FMC stockholders		0.04												0.03
Diluted earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)		0.03												0.04
Net income (loss) attributable to FMC stockholders (in USD per share)		$ 0.03												$ 0.04
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 4.4												$ 4.4
Pension and other postretirement benefits:
Unrealized actuarial gains (losses) and prior service (costs) credits, net of tax expense (benefit)		0.0												0.0
Reclassification of net actuarial and other (gain) loss and amortization of prior service costs, included in net income, net of tax (expense) benefit		(4.4)												(4.4)
Total pension and other postretirement benefits, net of tax expense (benefit) of $1.2 as computed and zero as reported for the three months ended September 30, 2022		(4.4)												(4.4)
Other comprehensive income (loss), net of tax		(4.4)												(4.4)
Comprehensive income (loss)		0.0												0.0
Comprehensive income (loss) attributable to FMC stockholders		$ 0.0												$ 0.0
Effect of Change | Combined Effect of Changes
Income Statement [Abstract]
Costs of sales and services								1.3							3.8
Gross margin								(1.3)							(3.8)
Total costs and expenses								1.3							3.8
Income from continuing operations before non-operating pension and postretirement charges (income), interest expense, net and income taxes								(1.3)							(3.8)
Non-operating pension and postretirement charges (income)								(3.6)							(10.8)
Income (loss) from continuing operations before income taxes								2.3							7.0
Provision (benefit) for income taxes								0.5							1.5
Income (loss) from continuing operations								1.8							5.5
Net income (loss)								1.8							5.5
Net income (loss) attributable to FMC stockholders								$ 1.8							$ 5.5
Basic earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)								$ 0.02							$ 0.05
Net income (loss) attributable to FMC stockholders								0.02							0.05
Diluted earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)								0.02							0.04
Net income (loss) attributable to FMC stockholders (in USD per share)								$ 0.02							$ 0.04
Statement of Comprehensive Income [Abstract]
Net income (loss)								$ 1.8							$ 5.5
Pension and other postretirement benefits:
Unrealized actuarial gains (losses) and prior service (costs) credits, net of tax expense (benefit)								(0.8)							(2.2)
Reclassification of net actuarial and other (gain) loss and amortization of prior service costs, included in net income, net of tax (expense) benefit								(2.0)							(6.3)
Total pension and other postretirement benefits, net of tax expense (benefit) of $1.2 as computed and zero as reported for the three months ended September 30, 2022								(2.8)							(8.5)
Other comprehensive income (loss), net of tax								(2.8)							(8.5)
Comprehensive income (loss)								(1.0)							(3.0)
Comprehensive income (loss) attributable to FMC stockholders								(1.0)							(3.0)
Effect of Change | Effect of FIFO Change
Income Statement [Abstract]
Costs of sales and services								1.3							3.8
Gross margin								(1.3)							(3.8)
Total costs and expenses								1.3							3.8
Income from continuing operations before non-operating pension and postretirement charges (income), interest expense, net and income taxes								(1.3)							(3.8)
Non-operating pension and postretirement charges (income)								0.0							0.0
Income (loss) from continuing operations before income taxes								(1.3)							(3.8)
Provision (benefit) for income taxes								(0.3)							(0.8)
Income (loss) from continuing operations								(1.0)							(3.0)
Net income (loss)								(1.0)							(3.0)
Net income (loss) attributable to FMC stockholders								$ (1.0)							$ (3.0)
Basic earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)								$ 0							$ (0.02)
Net income (loss) attributable to FMC stockholders								0							(0.02)
Diluted earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)								0							(0.03)
Net income (loss) attributable to FMC stockholders (in USD per share)								$ 0							$ (0.03)
Statement of Comprehensive Income [Abstract]
Net income (loss)								$ (1.0)							$ (3.0)
Pension and other postretirement benefits:
Unrealized actuarial gains (losses) and prior service (costs) credits, net of tax expense (benefit)								0.0							0.0
Reclassification of net actuarial and other (gain) loss and amortization of prior service costs, included in net income, net of tax (expense) benefit								0.0							0.0
Total pension and other postretirement benefits, net of tax expense (benefit) of $1.2 as computed and zero as reported for the three months ended September 30, 2022								0.0							0.0
Other comprehensive income (loss), net of tax								0.0							0.0
Comprehensive income (loss)								(1.0)							(3.0)
Comprehensive income (loss) attributable to FMC stockholders								(1.0)							(3.0)
Effect of Change | Effect of Pension Change
Income Statement [Abstract]
Costs of sales and services								0.0							0.0
Gross margin								0.0							0.0
Total costs and expenses								0.0							0.0
Income from continuing operations before non-operating pension and postretirement charges (income), interest expense, net and income taxes								0.0							0.0
Non-operating pension and postretirement charges (income)								(3.6)							(10.8)
Income (loss) from continuing operations before income taxes								3.6							10.8
Provision (benefit) for income taxes								0.8							2.3
Income (loss) from continuing operations								2.8							8.5
Net income (loss)								2.8							8.5
Net income (loss) attributable to FMC stockholders								$ 2.8							$ 8.5
Basic earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)								$ 0.02							$ 0.07
Net income (loss) attributable to FMC stockholders								0.02							0.07
Diluted earnings (loss) per common share attributable to FMC stockholders:
Continuing operations (in USD per share)								0.02							0.07
Net income (loss) attributable to FMC stockholders (in USD per share)								$ 0.02							$ 0.07
Statement of Comprehensive Income [Abstract]
Net income (loss)								$ 2.8							$ 8.5
Pension and other postretirement benefits:
Unrealized actuarial gains (losses) and prior service (costs) credits, net of tax expense (benefit)								(0.8)							(2.2)
Reclassification of net actuarial and other (gain) loss and amortization of prior service costs, included in net income, net of tax (expense) benefit								(2.0)							(6.3)
Total pension and other postretirement benefits, net of tax expense (benefit) of $1.2 as computed and zero as reported for the three months ended September 30, 2022								(2.8)							(8.5)
Other comprehensive income (loss), net of tax								(2.8)							(8.5)
Comprehensive income (loss)								0.0							0.0
Comprehensive income (loss) attributable to FMC stockholders								$ 0.0							$ 0.0

[1] For more detail on the components of these reclassifications and the affected line item in the condensed consolidated statements of income (loss) see Note 14.

[2] See condensed consolidated statements of comprehensive income (loss).

[3] See condensed consolidated statements of comprehensive income (loss).