Financing Arrangements - Term Facility (Details) - 2017 Term Facility	12 Months Ended
Dec. 31, 2017
Debt Instrument [Line Items]
Interest rate at end of period	5.30%
Amortization (in percent)	1.00%
LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	3.75%
Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)	2.75%

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant