Stock Compensation Plans - Total Share Awards (Details) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Stock and Restricted Stock Units
Number of Shares (in thousands)
Non-vested at beginning of year (in shares)	3,446
Granted (in shares)	1,702
Vested (in shares)	(1,105)
Forfeited (in shares)	(435)
Non-vested at end of year (in shares)	3,608	3,446
Weighted-Average Grant-Date Fair Value
Non-vested at beginning of year (in USD per share)	$ 48.43
Granted (in USD per share)	50.49	$ 53.11	$ 48.90
Vested (in USD per share)	42.73
Forfeited (in USD per share)	51.02
Non-vested at end of year (in USD per share)	$ 50.85	$ 48.43
Performance Shares
Number of Shares (in thousands)
Non-vested at beginning of year (in shares)	735
Granted (in shares)	422
Performance based adjustment (in shares)	391
Vested (in shares)	(739)
Forfeited (in shares)	(49)
Non-vested at end of year (in shares)	760	735
Weighted-Average Grant-Date Fair Value
Non-vested at beginning of year (in USD per share)	$ 49.56
Granted (in USD per share)	54.07	$ 50.26	$ 48.89
Performance based adjustment (in USD per share)	48.89
Vested (in USD per share)	48.89
Forfeited (in USD per share)	50.12
Non-vested at end of year (in USD per share)	$ 52.34	$ 49.56

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
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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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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).

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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).

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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.

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

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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.

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-Publisher FASB
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The net total number of shares (or other type of equity) under an equity-based award plan, other than a stock option plan, that were granted, vested and forfeited during the reporting period.

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

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-Publisher FASB
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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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Change in the weighted average exercise price of options outstanding.

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