Segments - Summary of Segment Results (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Total revenues		$ 1,378,900,000	$ 1,375,700,000	$ 2,681,300,000	$ 2,673,400,000
Operating income:
Operating income		214,800,000	260,300,000	454,300,000	518,900,000
Business Transformation Expenses		(28,500,000)	0	(32,200,000)	0
Consumer-to-Consumer
Operating income:
Business Transformation Expenses		(15,200,000)		(17,600,000)
Business Solutions
Operating income:
Business Transformation Expenses		(5,700,000)		(6,700,000)
Operating Segments
Operating income:
Operating income		298,800,000	277,400,000	552,600,000	536,000,000
Operating Segments | Consumer-to-Consumer
Revenues:
Total revenues		1,087,300,000	1,095,800,000	2,102,300,000	2,113,200,000
Operating income:
Operating income		269,900,000	251,900,000	497,500,000	483,200,000
Operating Segments | Business Solutions
Revenues:
Total revenues		96,600,000	100,800,000	190,200,000	200,000,000
Operating income:
Operating income		5,300,000	5,200,000	7,600,000	7,600,000
Other
Revenues:
Total revenues	[1]	195,000,000	179,100,000	388,800,000	360,200,000
Operating income:
Operating income	[1]	23,600,000	20,300,000	47,500,000	45,200,000
Not Allocated to Segments
Operating income:
State regulator matter accrual		(49,000,000)	0	(49,000,000)	0
Joint Settlement Agreements		0	(15,000,000)	0	(15,000,000)
Business Transformation Expenses		$ (35,000,000)	$ (2,100,000)	$ (49,300,000)	$ (2,100,000)

[1] Other consists primarily of the Company's bill payments businesses in the United States and Argentina.