Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118944033&loc=SL49130532-203044

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

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

Summary of Significant Accounting Policies, Contract Liabilities - Customer Loyalty Programs (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Contract Liabilities - Customer Loyalty Programs [Abstract]
Contract liabilities for customer loyalty programs	$ 12.5	$ 13.8	$ 14.9
Calculated under Cost Provision Methodology [Member]
Contract Liabilities - Customer Loyalty Programs [Abstract]
Contract liabilities for customer loyalty programs			1.9
Impact of Adopting ASC Topic 606 [Member]
Contract Liabilities - Customer Loyalty Programs [Abstract]
Contract liabilities for customer loyalty programs			$ 13.0