Business Combinations - Goodwill (Details) $ in Millions	Sep. 30, 2017 USD ($)
Business Combinations
Goodwill expected to be deducted for income tax purposes	$ 32.0

The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

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

Name:	us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant