Share-Based Compensation - Terms of Awards Granted (Details)	6 Months Ended
Jun. 30, 2018
MSUs
Share Based Compensation [Abstract]
Vesting period	3 years
Minimum of range for number of shares earned	0.00%
Maximum of range for number of shares earned	150.00%
Performance Shares
Share Based Compensation [Abstract]
Vesting period	3 years
Minimum of range for number of shares earned	0.00%
Maximum of range for number of shares earned	200.00%
RSUs
Share Based Compensation [Abstract]
Maximum of range for number of shares earned	100.00%

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.

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

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Share-based compensation arrangement by share-based payment award terms of award maximum.

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- Definition

A textual description of the accounting policy for share-based grants expense recognition and the plan under which awards are granted.

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