Stockholders' equity (Tables)

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

Accumulated other comprehensive loss is as follows:

	Total			Translation Adjustments			Postretirement Plans
Balance at December 31, 2018	$	(4,084.8	)	$	(896.7	)	$	(3,188.1	)
Other comprehensive income before reclassifications		136.8			23.8			113.0
Amounts reclassified from accumulated other comprehensive loss		(140.6	)		—			(140.6	)
Current period other comprehensive (loss) income		(3.8	)		23.8			(27.6	)
Balance at December 31, 2019		(4,088.6	)		(872.9	)		(3,215.7	)
Other comprehensive income before reclassifications		489.4			78.6			410.8
Amounts reclassified from accumulated other comprehensive loss		(340.3	)		(32.3	)		(308.0	)
Current period other comprehensive income		149.1			46.3			102.8
Balance at December 31, 2020		(3,939.5	)		(826.6	)		(3,112.9	)
Other comprehensive income (loss) before reclassifications		58.6			(43.6	)		102.2
Amounts reclassified from accumulated other comprehensive loss		616.8			4.0			612.8
Current period other comprehensive income (loss)		675.4			(39.6	)		715.0
Balance at December 31, 2021	$	(3,264.1	)	$	(866.2	)	$	(2,397.9	)

Schedule of Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss)

Amounts reclassified out of accumulated other comprehensive loss are as follows:

Year ended December 31,	2021			2020			2019
Translation Adjustments:
Adjustment for substantial completion of liquidation of foreign subsidiaries(i)	$	4.0		$	(32.3	)	$	—
Postretirement Plans:
Amortization of prior service cost(ii)		(6.2	)		5.9			5.9
Amortization of actuarial losses(ii)		178.9			(177.3	)		(149.7	)
Settlement loss(ii)		499.4			(142.1	)		(1.1	)
Total before tax		676.1			(345.8	)		(144.9	)
Income tax benefit		(59.3	)		5.5			4.3
Total reclassifications for the period	$	616.8		$	(340.3	)	$	(140.6	)

(i)  Reported in other (expense), net in the consolidated statements of income (loss)

(ii)  Included in net periodic postretirement cost (see Note 18, “Employee plans”)

Schedule of Changes in Common Stock and Treasury Stock

The following table summarizes the changes in shares of common stock and treasury stock:

	Common Stock		Treasury Stock
Balance at December 31, 2018		54.2		3.1
Debt exchange		10.6		—
Stock-based compensation		1.1		0.4
Balance at December 31, 2019		65.9		3.5
Stock-based compensation		0.9		0.3
Balance at December 31, 2020		66.8		3.8
Debt exchange		4.6		1.2
Stock-based compensation		1.1		0.3
Balance at December 31, 2021		72.5		5.3