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Equity-Based Compensation (Schedule of Number of Awards and Weighted Average Grant Date Fair Value) (Details) - $ / shares | 9 Months Ended
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Sep. 30, 2018 | Sep. 30, 2017
Performance stock units |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of awards (in shares) | 135,540 | 108,748
Weighted average grant date fair value (in USD per share) | $ 33.60 | $ 42.72
Restricted stock units |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of awards (in shares) | 95,674 | 120,048
Weighted average grant date fair value (in USD per share) | $ 36.81 | $ 37.14
Options |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of awards (in shares) | 0 | 25,000
Weighted average grant date fair value (in USD per share) | $ 0.00 | $ 42.35
Deferred stock units |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of awards (in shares) | 10,255 | 10,170
Weighted average grant date fair value (in USD per share) | $ 35.96 | $ 34.42
Common shares |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of awards (in shares) | 2,113 | 2,034
Weighted average grant date fair value (in USD per share) | $ 35.50 | $ 34.42

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- Definition 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). + References 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)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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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). + References 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)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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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. + References No definition available. + Details
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- Definition Gross number of share options (or share units) granted during the period. + References No definition available. + Details
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- Definition 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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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