Revenue - (Details)	6 Months Ended
	Jun. 30, 2018
Disaggregation of revenue
Revenue, Practical Expedient, Financing Component	true
Minimum
Disaggregation of revenue
Individual Merchants, Contract Term	30 days
Long Term Processing Contracts, Term	3 years
Capitalized Contract Cost, Amortization Period	20 months
Maximum
Disaggregation of revenue
Individual Merchants, Contract Term	5 years
Long Term Processing Contracts, Term	8 years
Capitalized Contract Cost, Amortization Period	7 years