Equity - Rollforward of Stockholders Equity (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2015				$ 1,908.3
Net income (loss)		$ 65.2	$ 742.3	113.5		$ 695.5
Less: Net income attributable to noncontrolling interests		1.8	4.0	2.2		5.3
Net income (loss)		67.0	746.3	115.7		700.8
Stock compensation plans				12.7
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation				(0.4)
Shares for benefit plan trust				0.1
Net pension and other benefit actuarial gains/(losses) and prior service costs, net of income tax		7.1	8.5	13.4	[1]	14.3
Net hedging gains/(losses) and other, net of income tax		0.1	$ 2.8	4.8	[1]	$ 3.3
Foreign currency translation adjustments	[1]			32.2
Dividends ($.165 per share)				(44.3)
Repurchases of common stock				(0.6)
Balance at June 30, 2016		2,041.9		$ 2,041.9
Dividends paid (in USD per share)				$ 0.165
FMC Stockholders’ Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2015				$ 1,865.7
Stock compensation plans				12.7
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation				(0.4)
Shares for benefit plan trust				0.1
Net pension and other benefit actuarial gains/(losses) and prior service costs, net of income tax	[1]			13.4
Net hedging gains/(losses) and other, net of income tax	[1]			4.8
Foreign currency translation adjustments	[1]			32.2
Dividends ($.165 per share)				(44.3)
Repurchases of common stock				(0.6)
Balance at June 30, 2016		1,997.1		1,997.1
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2015				42.6
Stock compensation plans				0.0
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation				0.0
Shares for benefit plan trust				0.0
Net pension and other benefit actuarial gains/(losses) and prior service costs, net of income tax	[1]			0.0
Net hedging gains/(losses) and other, net of income tax	[1]			0.0
Foreign currency translation adjustments	[1]			0.0
Dividends ($.165 per share)				0.0
Repurchases of common stock				0.0
Balance at June 30, 2016		$ 44.8		$ 44.8

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