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OPERATING LEASES - Narrative (FY) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Operating Leased Assets [Line Items] |  |  |
Net rental expense | $ 34.6 | $ 27.2 | $ 20.2
Minimum |  |  |
Operating Leased Assets [Line Items] |  |  |
Operating leases term, in years | 1 year |  |
Maximum |  |  |
Operating Leased Assets [Line Items] |  |  |
Operating leases term, in years | 15 years |  |

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- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717 + Details
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