Acquisitions - Cayan - Identifiable Intangible Assets (Details) - Cayan - USD ($) $ in Millions		6 Months Ended
	Jan. 11, 2018	Jun. 30, 2018
Identifiable intangible assets acquired
Total acquired identifiable intangible assets	$ 324.9
Weighted Average Amortization Period	7 years 8 months 12 days
Minimum
Identifiable intangible assets acquired
Weighted Average Amortization Period	1 year
Maximum
Identifiable intangible assets acquired
Weighted Average Amortization Period	10 years
Selling, general and administrative expenses
Key fair value assumptions
Acquisition-related costs		$ 15.2
Amortizable intangible assets | Level 2 and Level 3 measurements
Key fair value assumptions
Discount rate (as a percent)	12.00%
Attrition rate (as a percent)	12.00%
Effective tax rate (as a percent)	27.00%
Long-term sustainable growth rate (as a percent)	3.00%
Amortizable intangible assets | Level 2 and Level 3 measurements | Minimum
Key fair value assumptions
Pre-tax royalty rate (as a percent)	1.50%
Amortizable intangible assets | Level 2 and Level 3 measurements | Maximum
Key fair value assumptions
Pre-tax royalty rate (as a percent)	2.00%
Merchant relationships
Identifiable intangible assets acquired
Total acquired identifiable intangible assets	$ 179.5
Weighted Average Amortization Period	8 years
Channel relationships
Identifiable intangible assets acquired
Total acquired identifiable intangible assets	$ 80.4
Weighted Average Amortization Period	10 years
Technology
Identifiable intangible assets acquired
Total acquired identifiable intangible assets	$ 40.8
Weighted Average Amortization Period	5 years
Trade name
Identifiable intangible assets acquired
Total acquired identifiable intangible assets	$ 19.3
Weighted Average Amortization Period	3 years 6 months
Covenants not-to-compete
Identifiable intangible assets acquired
Total acquired identifiable intangible assets	$ 3.2
Weighted Average Amortization Period	2 years
Favorable lease
Identifiable intangible assets acquired
Total acquired identifiable intangible assets	$ 1.7
Weighted Average Amortization Period	6 years 6 months