Equity-Based Compensation (Schedule of Number of Awards and Weighted Average Grant Date Fair Value) (Details) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards (in shares)	25,000	0	37,500
Weighted Average Grant DAte Fair Value (in USD per share)	$ 12.85	$ 0.00	$ 7.67
Deferred stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards (in shares)	10,170	11,945	0
Weighted Average Grant Date Fair Value (in USD per share)	$ 34.42	$ 29.30	$ 0.00
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards (in shares)	2,034	3,185	21,318
Weighted Average Grant Date Fair Value (in USD per share)	$ 34.42	$ 29.30	$ 17.48
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards (in shares)	133,548	141,982	212,419
Weighted Average Grant Date Fair Value (in USD per share)	$ 36.56	$ 25.44	$ 17.78
Performance stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards (in shares)	108,748	0	396,714
Weighted Average Grant Date Fair Value (in USD per share)	$ 42.72	$ 0.00	$ 19.78

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).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

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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- Definition

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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- Definition

Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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