Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

DEBT - SMP Holdings Credit Facility (Narrative) (Details) - USD ($)	Dec. 31, 2017	May 31, 2017
Revolving credit facility
Debt Instrument [Line Items]
Accordion feature		$ 250,000,000
SMP Holdings \| Term Loan Credit Facility
Debt Instrument [Line Items]
Debt face amount	$ 200,000,000
SMP Holdings \| Revolving credit facility
Debt Instrument [Line Items]
Accordion feature	$ 250,000,000