Revenue - Narrative - (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) item	Jun. 30, 2019 USD ($)
Revenue
Revenues from contracts with customers \| $	$ 1,055.6	$ 1,275.0	$ 2,178.2	$ 2,550.4
Consumer money transfers
Revenue
Revenues from contracts with customers \| $	$ 948.3	1,088.2	$ 1,934.4	2,122.0
Number of performance obligations \| item	1		1
Number of integrated services involved in a transaction \| item	1		1
Consumer bill payments
Revenue
Revenues from contracts with customers \| $	$ 33.8	$ 94.8	$ 81.5	$ 244.5
Number of integrated services involved in a transaction \| item	1		1

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration