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Share-Based Payments - Summary of Performance and Phantom Shares by Grant Year (Details)	12 Months Ended
	Dec. 31, 2018 shares
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding (in shares)	178,666
Phantom Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding (in shares)	113,727
Grants 2016 | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	278,477
Vested (in shares)	(28,566)
Forfeited (in shares)	249,911
Outstanding (in shares)	0
Grants 2016 | Phantom Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	147,513
Vested (in shares)	(15,131.9787096774)
Forfeited (in shares)	132,381.021290323
Outstanding (in shares)	0
Grants 2017 | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	216,878
Vested (in shares)	0
Forfeited (in shares)	163,114
Outstanding (in shares)	53,764
Grants 2017 | Phantom Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	173,619
Vested (in shares)	0
Forfeited (in shares)	131,980
Outstanding (in shares)	41,639
Grants 2018 | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	215,273
Vested (in shares)	0
Forfeited (in shares)	90,371
Outstanding (in shares)	124,902
Grants 2018 | Phantom Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	150,185
Vested (in shares)	0
Forfeited (in shares)	78,097
Outstanding (in shares)	72,088

X

- Definition

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

+ 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)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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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

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

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
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- Definition

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
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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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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