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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Stock-based Compensation (Narrative) (Details) | 12 Months Ended
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Dec. 31, 2018
Restricted stock units |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Percentage vesting upon retirement for each full year of employment subsequent to the grant date | 25.00%

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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 Percentage of vesting of share-based compensation awards. + 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 (a)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Details
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