Stock Based Compensation (Rollforward of Stock Awards) (Details)	3 Months Ended
Mar. 31, 2019 $ / shares shares
Shares
Unvested and Potential Stock Awards, End of period (in shares)	1,063,840
Stock Awards
Shares
Unvested and Potential Stock Awards, Beginning of period (in shares)	1,227,483
Unvested and Potential Stock Awards, End of period (in shares)	1,063,840
Weighted-Average Grant Date Fair Value
Unvested and Potential Stock Awards, Beginning of period (in dollars per share) \| $ / shares	$ 23.14
Unvested and Potential Stock Awards, End of period (in dollars per share) \| $ / shares	$ 23.29
Deferred Stock Awards
Shares
Stock Awards Vested (in shares)	(20,032)
Deferred Stock Awards Forfeited (in shares)	(4,484)
Weighted-Average Grant Date Fair Value
Stock Awards Vested (in dollars per share) \| $ / shares	$ 16.95
Deferred Stock Awards Forfeited (in dollars per share) \| $ / shares	$ 17.84
Performance Share Awards
Shares
Stock Awards Vested (in shares)	(139,127)
Weighted-Average Grant Date Fair Value
Stock Awards Vested (in dollars per share) \| $ / shares	$ 23.02

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=109197908&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
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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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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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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 718
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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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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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