Acquisitions - Schedules of Assets and Liabilities Acquired (Details) - USD ($) $ in Thousands				3 Months Ended
	Jul. 01, 2019	Mar. 05, 2019	Jan. 24, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Cash consideration, net of cash and restricted cash acquired				$ 0	$ 568,426
Less:
Recorded goodwill				$ 2,418,288		$ 2,441,201
Go Fuel Card
Business Acquisition [Line Items]
Cash acquired	$ 5,589
Total consideration	260,455
Less:
Deposits	(5,169)
Accrued expenses	(420)
Recorded goodwill	$ 118,746
Weighted average life (in years)	8 years 10 months 24 days
Discovery Benefits
Business Acquisition [Line Items]
Cash and restricted cash acquired		$ 125,865
Cash consideration, net of cash and restricted cash acquired		300,191
Fair value of redeemable non-controlling interest		100,000
Less:
Accounts receivable		10,722
Property and equipment		4,904
Other assets		13,601
Accounts payable		(3,071)
Accrued expenses		(7,563)
Restricted cash payable		(125,346)
Deferred income taxes		(21,941)
Other liabilities		(9,814)
Recorded goodwill		$ 272,399
Weighted average life (in years)		7 years
Noventis
Business Acquisition [Line Items]
Cash acquired			$ 44,947
Total consideration			293,767
Less:
Accounts receivable			22,134
Property and equipment			549
Other assets			2,379
Accounts payable			(33,521)
Deferred income taxes			(21,194)
Other liabilities			(2,367)
Recorded goodwill			$ 209,887
Weighted average life (in years)			7 years 7 months 6 days
Network Relationships | Go Fuel Card
Less:
Intangible assets	$ 112,893
Weighted average life (in years)	10 years 1 month 6 days
Customer relationships | Go Fuel Card
Less:
Intangible assets	$ 33,963
Weighted average life (in years)	5 years
Customer relationships | Discovery Benefits
Business Acquisition [Line Items]
Total consideration		$ 400,191
Less:
Intangible assets		$ 213,600
Weighted average life (in years)		7 years 3 months 18 days
Customer relationships | Noventis
Less:
Intangible assets			$ 100,900
Weighted average life (in years)			8 years 3 months 18 days
Developed technologies | Discovery Benefits
Less:
Intangible assets		$ 38,900
Weighted average life (in years)		5 years 4 months 24 days
Developed technologies | Noventis
Less:
Intangible assets			$ 15,000
Weighted average life (in years)			2 years 10 months 24 days
Trademarks and trade names | Go Fuel Card
Less:
Intangible assets	$ 442
Weighted average life (in years)	1 year
Trademarks and trade names | Discovery Benefits
Less:
Intangible assets		$ 13,800
Weighted average life (in years)		7 years 3 months 18 days