Consolidated Statements of Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Operating activities:
Net income	$ 619.1	$ 540.8	$ 629.4
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization	357.9	350.7	346.7
Deferred income taxes	49.4	53.1	91.7
Equity in net (earnings) losses of affiliates	1.4	(1.0)	(2.6)
Share-based compensation	22.9	23.1	20.4
(Gain) loss on foreign currency derivative instruments	22.5	(14.1)	(6.3)
Foreign exchange (gain) loss	7.1	(3.0)	(1.5)
Restructuring charges	17.0	168.8	0.0
Write-off of software development costs	13.6	0.0	0.0
Gain on insurance recoveries related to hurricane damage	0.0	0.0	(17.9)
Distributions from affiliates	4.5	7.0	5.5
Settlement of foreign currency derivative instruments	(20.0)	11.9	13.9
Cash payments for restructuring charges	(10.0)	(6.3)	0.0
Refundable Mexican value added tax	(43.2)	(58.7)	0.0
Settlement of treasury lock agreements	0.0	(25.8)	0.0
Deemed mandatory repatriation tax	0.0	0.0	(18.7)
Insurance proceeds related to hurricane damage	0.0	0.0	17.9
Changes in working capital items:
Accounts receivable	25.5	38.2	(67.4)
Materials and supplies	21.7	0.5	(4.5)
Other current assets	(22.8)	5.0	(39.2)
Accounts payable and accrued liabilities	16.0	9.4	(24.0)
Other, net	(2.6)	4.4	6.5
Net cash provided by operating activities	1,080.0	1,104.0	949.9
Investing activities:
Capital expenditures	(411.9)	(587.2)	(520.3)
Purchase or replacement of assets under operating leases	(78.2)	(39.0)	(98.9)
Property investments in MSLLC	(24.8)	(27.5)	(26.1)
Investments in and advances to affiliates	(7.4)	(36.7)	(19.2)
Insurance proceeds related to hurricane damage	0.0	0.0	7.6
Proceeds from disposal of property	12.9	22.1	8.7
Other, net	(16.6)	(8.0)	(3.7)
Net cash used for investing activities	(526.0)	(676.3)	(651.9)
Financing activities:
Net short-term borrowings	0.0	0.0	(348.1)
Proceeds from issuance of long-term debt	545.6	847.5	499.4
Repayment of long-term debt	(18.0)	(285.0)	(81.5)
Dividends paid	(152.3)	(144.3)	(147.5)
Shares repurchased	(888.9)	(792.5)	(243.5)
Debt issuance and retirement costs paid	(6.6)	(11.6)	(8.0)
Proceeds from employee stock plans	9.9	7.0	1.8
Net cash used for financing activities	(510.3)	(378.9)	(327.4)
Effect of Exchange Rate on Cash and Cash Equivalents	(4.3)	(0.5)	(4.2)
Cash and cash equivalents:
Net increase (decrease) during each year	39.4	48.3	(33.6)
At beginning of year	148.8	100.5	134.1
At end of year	188.2	148.8	100.5
Non-cash investing and financing activities:
Capital expenditures accrued but not yet paid at end of year	22.3	24.0	26.9
Other investing activities accrued but not yet paid at the end of the year	31.9	31.2	53.8
Finance lease obligations incurred	0.8	0.0	0.0
Non-cash asset acquisitions	2.8	0.5	0.7
Dividends accrued but not yet paid at end of year	40.6	39.0	36.6
Cash payments:
Interest paid, net of amounts capitalized	144.5	110.5	105.0
Income tax payments, net of refunds	$ 182.3	$ 170.5	$ 221.0