Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net (loss) earnings including noncontrolling interest	$ (204.0)	$ 129.9
Other comprehensive (loss) income, net of tax
Foreign currency translation gain (loss)	(603.4)	51.8
Net actuarial (loss) gain and prior service cost	1.8	(1.0)
Realized gain on interest rate swap	0.5	0.6
Net gain (loss) on marketable securities held in trust fund	8.0	10.0
Other comprehensive income (loss)	(593.1)	61.4
Comprehensive (loss) income	(797.1)	191.3
Less: Comprehensive (loss) income attributable to noncontrolling interest	(8.3)	(1.0)
Comprehensive (loss) income attributable to Mosaic	$ (788.8)	$ 192.3

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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