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Stock-Based Compensation and Directors Stock Purchase Plan (Summary Of The Status Of Nonvested Share Awards) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Nonvested Share Awards [Roll Forward]
Nonvested, share awards, beginning balance	1,159,180
Granted, Shares	244,468
Vested, Shares	(292,100)
Forfeited, Shares	(11,682)
Nonvested, share awards, ending balance	1,099,866	1,159,180
Nonvested Weighted Average Grant Date Fair Value [Roll Forward]
Nonvested, Weighted Average Grant Date Fair Value, Beginning Balance	$ 52.11	$ 45.30
Granted, Weighted Average Grant Date Fair Value		60.90
Vested, Weighted Average Grant Date Fair Value		32.40
Forfeited, Weighted Average Grant Date Fair Value		51.77
Nonvested , Weighted Average Grant Date Fair Value, Ending Balance		$ 52.11

X

- Definition

Nonvested Share Awards, Beginning and Ending Balances

+ References

No definition available.

+ Details

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X

- Definition

Number of nonvested shares that were forfeited during the reporting period.

+ References

No definition available.

+ Details

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X

- Definition

Number of nonvested shares that were granted during the reporting period.

+ References

No definition available.

+ Details

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X

- Definition

Number of nonvested shares that vested during the reporting period

+ References

No definition available.

+ Details

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Nonvested Share Awards Vested In Period Weighted Average Grant Date Fair Value

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Nonvested Share Awards Weighted Average Grant Date Unit Fair Value

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No definition available.

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X

- Definition

Share-Based Compensation, Forfeited, Nonvested Share Award, Weighted Average Grant Date Fair Value

+ References

No definition available.

+ Details

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- Definition

Share Based Compensation, Granted, Nonvested Share Award Weighted Average Grant Date Fair Value

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No definition available.

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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.

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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.

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No definition available.

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