Share-Based Payments Non-vested (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
RSUs and DSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested awards outstanding at the beginning of the period (in shares)	1.0
Awards granted (in shares)	0.5
Vested (in shares)	(0.3)
Forfeited (in shares)	(0.2)
Non-vested awards outstanding at the end of the period (in shares)	1.0	1.0
Equity instruments other than options, nonvested, weighted average grant date fair value	$ 56.21	$ 68.18
Weighted-average fair value	48.81
Vested, weighted-average grant date fair value (in dollars per unit)	84.81
Forfeited, weighted-average grant date fair value (in dollars per unit)	$ 64.12
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 14.8	$ 23.6	$ 24.8
Performance shares (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested awards outstanding at the beginning of the period (in shares)	0.6
Awards granted (in shares)	0.3	0.3	0.2
Vested (in shares)	0.0
Forfeited (in shares)	(0.2)
Non-vested awards outstanding at the end of the period (in shares)	0.7	0.6
Equity instruments other than options, nonvested, weighted average grant date fair value	$ 58.12	$ 70.37
Weighted-average fair value	52.60	$ 53.31	$ 78.30
Vested, weighted-average grant date fair value (in dollars per unit)	0
Forfeited, weighted-average grant date fair value (in dollars per unit)	66.22
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instrument Other than Option, Nonvested, Intrinsic Value	$ 32.76
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Awards granted (in shares)	0.5	0.5	0.4
Equity instruments other than options, nonvested, weighted average grant date fair value	$ 48.99	$ 55.03	$ 72.78

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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- Definition

Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(3)
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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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-Publisher FASB
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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

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Per share or unit weighted-average intrinsic value of nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

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-Publisher FASB
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- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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