Share-Based Compensation (Narrative) (Details)	12 Months Ended
Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares Authorized \| shares	5,298,056
Share-based compensation expense	$ 14,200,000	$ 13,900,000	$ 10,900,000
Share-based compensation expense, tax benefit	$ 5,000,000	$ 4,900,000	$ 3,800,000
Share-based compensation, share-based award, participant age, minimum	55
Share-based compensation, share-based payment award, participant period of service	15 years
Treasury stock, shares, acquired \| shares	(312,427)	(262,140)	(217,674)
Total compensation cost not yet recognized	$ 16,400,000
Total compensation cost not yet recognized, period for recognition	1 year 5 months 19 days
Restricted stock vested in period, total fair value	$ 13,500,000	$ 10,800,000	$ 9,100,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Award requisite service period	10 years
Total compensation cost not yet recognized	$ 0

Share-based Compensation, Share-Based Award, Participant Age, Minimum

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Share-based Compensation, Share-based Payment Award, Participant Period of Service

+ References

No definition available.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 14.F)
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-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14
-Section F

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- Definition

Minimum period the individual is required to perform services to be fully vested under the deferred compensation arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 55
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- Definition

Unrecognized cost of unvested share-based compensation awards.

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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Number of shares that have been repurchased during the period and are being held in treasury.

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-Name Regulation S-X (SX)
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-Name Regulation S-X (SX)
-Number 210
-Section 04
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