Debt Instrument, Deferred Finance Costs

No definition available.

Name:	flt_DebtInstrumentDeferredFinanceCosts
Namespace Prefix:	flt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line Of Credit Facility Additional Available Borrowing Capacity

+ References

No definition available.

+ Details

Name:	flt_LineOfCreditFacilityAdditionalAvailableBorrowingCapacity
Namespace Prefix:	flt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Debt - Summary of Debt Instruments Narrative (Details) - USD ($)			3 Months Ended	12 Months Ended
	Jan. 20, 2017	Oct. 24, 2014	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Unused facility fee, as percentage of unused portion			0.30%
Deferred finance costs			$ 4,800,000
Securitization Facility
Debt Instrument [Line Items]
Amended securitization facility			$ 950,000,000
Unused facility fee, as percentage of unused portion			0.40%	0.40%
Program fee			one month LIBOR
Revolving line of credit A Facility—domestic
Debt Instrument [Line Items]
Effective interest rate			3.38%
Revolving line of credit B Facility—foreign
Debt Instrument [Line Items]
Effective interest rate			2.00%
Revolving line of credit B Facility—swing line
Debt Instrument [Line Items]
Effective interest rate			1.97%
Term Loan A
Debt Instrument [Line Items]
Line of credit facility initial borrowing, unamortized debt discount			$ 5,600,000
Term Loan B
Debt Instrument [Line Items]
Line of credit facility initial borrowing, unamortized debt discount			$ 700,000
Effective interest rate			3.88%
Commercial Paper \| Securitization Facility
Debt Instrument [Line Items]
Basis spread on variable rate			0.80%		0.86%
Program fee rate			1.9139%		1.55%
Secured Debt
Debt Instrument [Line Items]
Additional borrowing capacity		$ 750,000,000
Secured Debt \| Term A Loan Facility
Debt Instrument [Line Items]
Amended securitization facility			$ 1,285,000,000.000
Secured Debt \| Term Loan A
Debt Instrument [Line Items]
Amended securitization facility			2,690,000,000.00
Secured Debt \| Term Loan B
Debt Instrument [Line Items]
Amended securitization facility			350,000,000.0
Secured Debt \| Revolving A Facility
Debt Instrument [Line Items]
Amended securitization facility			800,000,000
Secured Debt \| Revolving B Facility
Debt Instrument [Line Items]
Amended securitization facility			450,000,000
Secured Debt \| Revolving C Facility
Debt Instrument [Line Items]
Amended securitization facility			$ 35,000,000
London Interbank Offered Rate (LIBOR) \| Commercial Paper \| Securitization Facility
Debt Instrument [Line Items]
Basis spread on variable rate			0.90%
Eurodollar \| Secured Debt \| Term Loan B
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Base Rate \| Secured Debt \| Term Loan B
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Blended Rate Of LIBOR And Commercial Paper Rates Based On Weighted Average Advance \| Commercial Paper \| Securitization Facility
Debt Instrument [Line Items]
Basis spread on variable rate			0.86%
Minimum \| Secured Debt
Debt Instrument [Line Items]
Unused facility fee, as percentage of unused portion			0.20%
Minimum \| Federal Funds Rate Plus \| Secured Debt
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Maximum \| Secured Debt
Debt Instrument [Line Items]
Unused facility fee, as percentage of unused portion			0.40%
Maximum \| Eurodollar \| Secured Debt
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%