Revenue Disclosures - (Details) - Receivables From Franchise Revenue Transactions - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Billed and unbilled receivables	$ 65.9	$ 62.6
Billed and unbilled receivables, accumulated allowance for credit loss	$ 2.1	$ 4.6

Amount of accumulated credit loss for right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130533-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118955202&loc=SL82895884-210446

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447

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