EPS - Narrative (Details) - shares	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Participating securities (in shares)	338,375	497,492

This element represents nonvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). Basic and dilutive earnings per share are generally disclosed for such shares using the two-class method.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration