Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Acquisitions - Narrative (Details) $ in Millions		3 Months Ended
Acquisitions - Narrative (Details) $ in Millions	Feb. 01, 2018 branch	Mar. 31, 2018 USD ($)
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Purchase price of acquisitions \| $		$ 21.9
Minnesota, North Dakota, South Dakota and Nebraska \| ArmCom Distributing Company
Business Acquisition [Line Items]
Number of branch locations	5
Wentzville and Herculaneum, Missouri \| R M Supply, Inc.
Business Acquisition [Line Items]
Number of branch locations	2