WEX (WEX) 10-Q 10 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	May 03, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	WEX Inc.
Trading Symbol	WEX
Entity Central Index Key	1,309,108
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		43,082,580

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Payment processing revenue	$ 168,454	$ 136,378
Account servicing revenue	78,704	61,539
Finance fee revenue	49,682	43,372
Other revenue	57,989	50,068
Total revenues	354,829	291,357
Cost of services
Processing costs	79,640	64,334
Service fees	12,326	17,600
Provision for credit losses	13,990	12,231
Operating interest	8,485	4,893
Depreciation and amortization	20,450	17,384
Total cost of services	134,891	116,442
General and administrative	55,309	42,151
Sales and marketing	56,541	40,158
Depreciation and amortization	29,726	31,854
Operating income	78,362	60,752
Financing interest expense	(27,337)	(27,148)
Net foreign currency gain	390	8,442
Net unrealized gains on interest rate swap agreements	13,508	1,565
Income before income taxes	64,923	43,611
Income taxes	15,589	14,535
Net income	49,334	29,076
Less: Net income (loss) from non-controlling interest	701	(325)
Net income attributable to shareholders	$ 48,633	$ 29,401
Net income attributable to WEX Inc. per share:
Basic (in dollars per share)	$ 1.13	$ 0.69
Diluted (in dollars per share)	$ 1.12	$ 0.68
Weighted average common shares outstanding:
Basic (in shares)	43,049	42,871
Diluted (in shares)	43,450	43,119

CONDENSED CONSOLIDATED STATEME3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 49,334	$ 29,076
Changes in investment securities, net of tax expense of $1	0	3
Foreign currency translation	1,935	16,620
Comprehensive income	51,269	45,699
Less: Comprehensive income (loss) attributable to non-controlling interest	991	(283)
Comprehensive income attributable to WEX Inc.	$ 50,278	$ 45,982

CONDENSED CONSOLIDATED STATEME4

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Statement of Comprehensive Income [Abstract]
Changes in investment securities, tax effect	$ 1

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 373,169	$ 508,072
Restricted cash	26,716	18,866
Accounts receivable (net of allowances of $31,443 in 2018 and $30,207 in 2017)	2,770,399	2,517,980
Securitized accounts receivable, restricted	170,327	150,235
Prepaid expenses and other current assets	80,598	69,413
Total current assets	3,421,209	3,264,566
Property, equipment and capitalized software (net of accumulated depreciation of $279,693 in 2018 and $264,928 in 2017)	162,968	163,908
Goodwill	1,876,922	1,876,132
Other intangible assets (net of accumulated amortization of $427,812 in 2018 and $392,827 in 2017)	1,119,768	1,154,047
Investment securities	23,049	23,358
Deferred income taxes, net	6,914	7,752
Other assets	144,790	253,088
Total assets	6,755,620	6,742,851
Liabilities and Stockholders’ Equity
Accounts payable	947,317	811,362
Accrued expenses	298,179	315,346
Short-term deposits	778,858	986,989
Short-term debt, net	300,710	397,218
Other current liabilities	31,825	24,795
Total current liabilities	2,356,889	2,535,710
Long-term debt, net	2,132,283	2,027,752
Long-term deposits	330,043	306,865
Deferred income taxes, net	132,442	119,283
Other liabilities	33,774	32,683
Total liabilities	4,985,431	5,022,293
Stockholders’ Equity
Common Stock $0.01 par value; 175,000 shares authorized; 47,500 shares issued in 2018 and 47,352 in 2017; 43,072 shares outstanding in 2018 and 43,022 in 2017	475	473
Additional paid-in capital	567,038	569,319
Retained earnings	1,453,957	1,404,683
Accumulated other comprehensive loss	(89,150)	(90,795)
Treasury stock at cost; 4,428 shares in 2018 and 2017	(172,342)	(172,342)
Total WEX Inc. stockholders’ equity	1,759,978	1,711,338
Non-controlling interest	10,211	9,220
Total stockholders’ equity	1,770,189	1,720,558
Total liabilities and stockholders’ equity	$ 6,755,620	$ 6,742,851

CONDENSED CONSOLIDATED BALANCE6

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts receivable, reserve for credit losses	$ 31,443	$ 30,207
Property, equipment and capitalized software, accumulated depreciation	279,693	264,928
Accumulated amortization	$ 427,812	$ 392,827
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	175,000,000	175,000,000
Common stock, shares issued (in shares)	47,500,000	47,352,000
Common stock, shares outstanding (in shares)	43,072,000	43,022,000
Treasury stock, shares (in shares)	4,428,000	4,428,000

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands		Total	Common Stock Issued	Additional Paid–In Capital	Accumulated Other Comprehensive Loss	Treasury Stock	Retained Earnings	Non–Controlling Interest
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance		$ 1,506,010	$ 472	$ 547,627	$ (122,839)	$ (172,342)	$ 1,244,534	$ 8,558
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment	[1]	263					263
Beginning Balance (in shares) at Dec. 31, 2016			47,173
Beginning balance at Dec. 31, 2016		1,505,747	$ 472	547,627	(122,839)	(172,342)	1,244,271	8,558
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued (in shares)			154
Stock issued		73	$ 1	72
Share repurchases for tax withholdings		(9,021)		(9,021)
Stock–based compensation expense		6,457		6,457
Changes in available-for-sale securities, net of tax expense		3			3
Foreign currency translation		16,620			16,578			42
Net income		29,076					29,401	(325)
Ending Balance (in shares) at Mar. 31, 2017			47,327
Ending balance at Mar. 31, 2017		1,549,218	$ 473	545,135	(106,258)	(172,342)	1,273,935	8,275
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance		1,721,199	$ 473	569,319	(90,795)	(172,342)	1,405,324	9,220
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment	[2]	641					641
Beginning Balance (in shares) at Dec. 31, 2017			47,352
Beginning balance at Dec. 31, 2017		1,720,558	$ 473	569,319	(90,795)	(172,342)	1,404,683	9,220
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued (in shares)			148
Stock issued		576	$ 2	574
Share repurchases for tax withholdings		(11,810)		(11,810)
Stock–based compensation expense		8,955		8,955
Changes in available-for-sale securities, net of tax expense		0
Foreign currency translation		1,935			1,645			290
Net income		49,334					48,633	701
Ending Balance (in shares) at Mar. 31, 2018			47,500
Ending balance at Mar. 31, 2018		$ 1,770,189	$ 475	$ 567,038	$ (89,150)	$ (172,342)	$ 1,453,957	$ 10,211
[1]	Includes the impact of modified retrospective transition as part of the Company’s adoption of ASU 2016–09 to recognize previously disallowed excess tax benefits that increased a net operating loss.
[2]	Includes the impact of modified retrospective adoption of Topic 606.

CONDENSED CONSOLIDATED STATEME8

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Statement of Stockholders' Equity [Abstract]
Changes in available-for-sale securities, tax effect	$ 1

CONDENSED CONSOLIDATED STATEME9

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net income		$ 49,334	$ 29,076
Adjustments to reconcile net income to net cash provided by (used for) operating activities:
Net unrealized gain		(10,790)	(2,991)
Stock-based compensation		8,955	6,457
Depreciation and amortization		50,176	49,238
Debt restructuring and debt issuance cost amortization		3,676	1,954
Provision for deferred taxes		12,705	10,517
Provision for credit losses		13,990	12,231
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable and securitized receivables		(273,124)	(194,859)
Prepaid expenses and other current and other long-term assets		117,069	(1,024)
Accounts payable		133,716	60,650
Accrued expenses		(17,404)	(32,547)
Income taxes		92	685
Other current and other long-term liabilities		(3,152)	(331)
Net cash provided by (used for) operating activities		85,243	(60,944)
Cash flows from investing activities
Purchases of property, equipment and capitalized software		(14,770)	(21,693)
Purchase of equity investment		(2,307)	0
Purchases of investment securities		(121)	(114)
Maturities of investment securities		72	229
Net cash used for investing activities		(17,126)	(21,578)
Cash flows from financing activities
Repurchase of share-based awards to satisfy tax withholdings		(11,810)	(9,020)
Proceeds from stock option exercises		576	72
Net change in deposits		(185,433)	(78,392)
Net activity on other debt		(19,027)	(19,010)
Borrowings on revolving credit facility		488,503	1,237,606
Repayments of revolving credit facility		(625,821)	(1,035,026)
Borrowings on term loans		153,000	0
Repayments on term loans		(9,076)	(8,688)
Debt issuance costs		(2,907)	0
Net change in securitized debt		19,402	3,354
Net cash (used for) provided by financing activities		(192,593)	90,896
Effect of exchange rate changes on cash, cash equivalents and restricted cash		(2,577)	2,926
Net change in cash, cash equivalents and restricted cash		(127,053)	11,300
Cash, cash equivalents and restricted cash, beginning of period	[1]	526,938	213,342
Cash, cash equivalents and restricted cash, end of period	[1]	399,885	224,642
Capital expenditures incurred but not paid		4,801	4,352
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash, cash equivalents and restricted cash	[1]	$ 526,938	$ 213,342
[1]	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within our unaudited condensed consolidated balance sheets to amounts reported within our unaudited condensed consolidated statements of cash flows for the three months ended March 31, 2018 and 2017:

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	1. Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10–Q and Rule 10–01 of Regulation S–X. Accordingly, they do not include all information and notes required by GAAP for complete financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the financial statements that are included in the Company’s Annual Report on Form 10–K for the year ended December 31, 2017 , filed with the SEC on March 1, 2018 . In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results for any future periods or the year ending December 31, 2018 . The Company rounds amounts in the unaudited condensed consolidated financial statements to thousands and calculates all per-share data from underlying whole-dollar amounts. Thus, certain amounts may not foot, crossfoot or recalculate based on reported numbers due to rounding. Changes to Prior Year Financial Statement Presentation Effective January 1, 2018, the Company modified the presentation of the balance sheets and statements of income and changed how we allocate certain costs to our segments. These changes enhance the information reported to the users of our financial statements. The Company now classifies assets and liabilities as current and non-current within our unaudited condensed consolidated balance sheets as defined according to the normal twelve month operating cycle of our business. Prior period amounts have been recast to conform with this presentation. As a result of this change, total assets and total liabilities have increased by approximately $3.7 million compared to what was reported within our Annual Report on Form 10–K for the year ended December 31, 2017 due to a gross-up of interest rate swap arrangements to reflect their corresponding short and long-term portions. See Note 11 , Fair Value, for more information on the fair value of our interest rate swap arrangements. Additionally, the Company has modified the presentation of certain line items in its unaudited condensed consolidated statements of income. Under the new presentation, costs of services are segregated from other operating expenses. Operating expenses have been reclassified into functional categories in order to provide additional detail into the underlying drivers of changes in operating expenses and align presentation with industry practice. The revised presentation did not result in a change to previously reported revenues, operating income, income before income taxes or net income. Effective with the change in financial statement presentation noted above, the Company now reports expenses in the categories noted below. No changes have been made to non-operating expenses. Cost of Services • Processing costs - The Company’s processing costs consist of expenses related to processing transactions, servicing customers and merchants, cost of goods sold related to hardware and other product sales. • Service fees - The Company incurs costs from third-party networks utilized to deliver payment solutions. Additionally, other third-parties are utilized in performing services directly related to generating revenue. With the adoption of Topic 606 effective January 1, 2018, certain network fees paid to third-party networks are no longer recorded as service fees and are now presented as a reduction of revenues. • Provision for credit losses - Changes in the reserve for credit loss are the result of changes in management’s estimate of the losses in the Company’s outstanding portfolio of receivables, including losses from fraud. • Operating interest - The Company incurs interest expense on the operating debt obtained to provide liquidity for its short-term receivables. • Depreciation and amortization - The Company has identified those tangible and intangible assets directly associated with providing a service that generates revenue and records the depreciation and amortization associated with those assets under this category. Such assets include processing platforms and related infrastructure, acquired developed technology intangible assets, and other similar asset types. Other Operating Expenses • General and administrative - General and administrative includes compensation and related expenses for the executive, finance and accounting, other information technology, human resources, legal and other corporate functions. Also included are corporate facilities expenses, certain third-party professional service fees and other corporate expenses. • Sales and marketing - The Company’s sales and marketing expenses relate primarily to compensation, benefits, sales commissions and related expenses for sales, marketing and other related activities. With the adoption of Topic 606 effective January 1, 2018, certain payments to partners are now classified as sales and marketing expenses. • Depreciation and amortization - The depreciation and amortization associated with tangible and intangible assets, that are not considered to be directly associated with providing a service that generates revenue, are recorded as other operating expenses. Such assets include corporate facilities and information technology assets and acquired intangible assets other than those included in cost of services.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	2. Recent Accounting Pronouncements The following table provides a brief description of accounting pronouncements adopted during the quarter and recent accounting pronouncements that could have a material effect on our financial statements: Standard Description Date/Method of Adoption Effect on financial statements or other significant matters Adopted During the Three Months Ended March 31, 2018 ASU 2014–09 This standard supersedes most existing revenue recognition guidance under GAAP. The new revenue recognition standard requires entities to recognize revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In addition, the standard requires disclosure of the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The Company adopted this standard on January 1, 2018. The guidance permits two methods of adoption: full retrospective approach, which requires an entity to restate each prior period that is reported in the financial statements and modified retrospective approach, which requires a cumulative adjustment to retained earnings as of the effective date, without restatement of prior period amounts. The Company adopted the standard using the modified retrospective method, applied to those contracts which were not completed as of January 1, 2018. The Company’s revenue from discount and interchange, transaction processing and certain fees is within the scope of Topic 606. FASB and its Transition Resource Group have issued clarifications on various aspects of ASU 2014–09. There were three primary impacts to the Company resulting from the adoption of Topic 606, which are described below. As of January 1, 2018, we recorded $0.6 million cumulative-effect adjustment, net of the associated tax effect, related to the deferral of capitalizable costs to obtain a contract within our Health and Employee Benefit Solutions segment. These commissions are amortized to sales and marketing expense over a useful life that considers the contract term, our commission policy, renewal experience and the transfer of services to which the asset relates. ASU 2017–07 This standard changes the presentation of net benefit pension costs by requiring the disaggregation of certain of its components. Under the guidance, companies are required to present the service cost component in the same income statement line item(s) as other employee compensation costs arising from services rendered during the period. The other components of net benefit cost will be presented in the income statement separately from the service cost component and outside the subtotal of operating income, if one is presented. Additionally, only the service cost component will be eligible for capitalization under the new guidance. The Company adopted ASU 2017–07 effective January 1, 2018. The adoption did not have a material impact on our results of operations, cash flows or consolidated financial position. ASU 2016–18 This standard clarifies the classification and presentation of restricted cash in the statement of cash flows. The statement of cash flows must explain the change during the period in the total of cash and cash equivalents and amounts described as restricted cash or cash equivalents. The Company retrospectively adopted ASU 2016–18 effective January 1, 2018. This retrospective adoption resulted in including restricted cash in cash, cash equivalents and restricted cash when reconciling the beginning of year and end of year amounts presented on the unaudited condensed consolidated statements of cash flows. A reconciliation of cash, cash equivalents and restricted cash as reported within our unaudited condensed consolidated balance sheets is included within our unaudited condensed consolidated statements of cash flows. ASU 2016–01 This standard requires equity investments, except those accounted for under the equity method of accounting, or those that result in consolidation of the investee, to be measured at fair value with changes in fair value recognized in net income. The Company adopted ASU 2016–01 effective All gains and losses on investment securities are now reflected as non-operating income within our unaudited condensed consolidated statements of income. The adoption did not have a material impact on our results of operations, balance sheet or cash flows. Not Yet Adopted as of March 31, 2018 ASU 2016–02 Leases (Topic 842) This standard increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. Certain qualitative and quantitative disclosures are required. The standard is effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period. When transitioning, the standard requires leases to be recognized and measured at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the impact the standard will have on the consolidated financial statements and related disclosures. ASU 2016–13 Financial Instruments–Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This standard requires financial assets measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of expected credit losses will be based on historical experience, current conditions, and reasonable and supportable forecasts that impact the collectability of the reported amount. The standard is effective for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. The Company is evaluating the impact the standard will have on the consolidated financial statements and related disclosures.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	3. Revenue The Company adopted Topic 606 on January 1, 2018, utilizing the modified retrospective method. See Note 2, Recent Accounting Pronouncements, for further information regarding the adoption impact. Under the modified retrospective method, prior period comparable financial information continues to be presented under the guidance of ASC 605, Revenue Recognition. Please see the Company’s Annual Report on Form 10–K for the year ended December 31, 2017 for our accounting policies applied to revenue recognition prior to adoption of Topic 606. Topic 606 does not apply to rights or obligations associated with financial instruments, including the Company’s finance fee and interest income from banking relationships and cardholders, certain other fees associated with cardholder arrangements and commissions paid related to such agreements, which continue to be within the scope of Accounting Standards Codification Topic 310, Receivables (“Topic 310”). The vast majority of the Company’s Topic 606 revenue is derived from stand-ready obligations to provide payment processing, transaction processing and SaaS services and support. Revenue is recognized based on the value of services transferred to date using a time elapsed output method. Point-in-time revenue recognized during the three months ended March 31, 2018 was not material. We disaggregate our revenue from contracts with customers by service-type for each of our segments, as we believe it best depicts how the nature, amount, timing and uncertainty of our revenue and cash flows are affected by economic factors. The following table disaggregates our consolidated revenue: Three Months Ended March 31, 2018 (In thousands) Fleet Solutions Travel and Corporate Solutions Health and Employee Benefit Solutions Total Topic 606 revenues Payment processing revenue $ 106,978 $ 44,777 $ 16,699 $ 168,454 Account servicing revenue 8,466 9,469 27,025 44,960 Other revenue 17,042 1,117 8,142 26,301 Total Topic 606 revenues $ 132,486 $ 55,363 $ 51,866 $ 239,715 Topic 310 revenues Account servicing revenue $ 33,744 — — $ 33,744 Finance fee revenue 43,604 259 5,819 49,682 Other revenue 20,531 11,157 — 31,688 Total Topic 310 revenues $ 97,879 $ 11,416 $ 5,819 $ 115,114 Total revenues $ 230,365 $ 66,779 $ 57,685 $ 354,829 Payment Processing Revenue Payment processing revenue consists primarily of interchange income. Interchange income is a fee paid by a merchant bank (“merchant”) to the card-issuing bank (generally the Company) in exchange for the Company facilitating and processing transactions with cardholders. Interchange fees are set by the card network. WEX processes transactions through both closed-loop and open-loop networks. • Our Fleet Solutions segment interchange income primarily relates to revenue earned on transactions processed through the Company’s proprietary closed-loop fuel networks. In closed-loop network arrangements, written contracts are entered into between the Company and merchants, which determine the interchange fee charged on transactions. The Company extends short-term credit to the fleet cardholder and pays the merchant the purchase price for the cardholder’s transaction, less the interchange fees the Company retains. The Company collects the total purchase price from the fleet cardholder. In Europe, interchange income is specifically derived from the difference between the negotiated price of fuel from the supplier and the agreed upon price paid by fleet cardholders. • Interchange income in our Travel and Corporate Solutions and Health and Employee Benefit Solutions segments relates to revenue earned on transactions processed through open-loop networks. In open-loop network arrangements, there are several intermediaries involved between the merchant and the cardholder and written contracts between all parties involved in the process do not exist. Rather, the transaction is governed by the rates determined by the payment network at the point-of-sale. This framework dictates the interchange rate, the risk of loss, dispute procedures and timing of payment. For these transactions, there is an implied contract between the Company and the merchant. In our Travel and Corporate Solutions segment, the Company remits payment to the card network for the purchase price of the cardholder transaction, less the interchange fees the Company earns. The Company collects the total purchase price from the cardholder. • In our Health and Employee Benefit Solutions segment, funding of transactions and collections from cardholders is performed by third-party sponsor banks, who remit a portion of the interchange fee to us. The Company has determined that the merchant is the customer as it relates to interchange income regardless of the type of network through which transactions are processed. The Company’s primary performance obligation to merchants is a stand-ready commitment to provide payment and transaction processing services as the merchant requires, which is satisfied over time in daily increments. Since the timing and quantity of transactions to be processed by us is not determinable, the total consideration is determined to be variable consideration. The variable consideration for our payment and transaction processing service is usage-based and therefore it specifically relates to our efforts to satisfy our obligation. The variability is satisfied each day the service is provided to the customer. We directly ascribe variable fees to the distinct day of service to which it relates, and we consider the services performed each day in order to ascribe the appropriate amount of total fees to that day. Therefore, we measure interchange income on a daily basis based on the services that are performed on that day. In determining the amount of consideration received related to payment and transaction processing services provided, the Company assessed other intermediaries involved in the processing of transactions, including merchant acquirers, card networks, sponsor banks and third-party payment processors, and assessed whether the Company controls such services performed by other intermediaries according to principal-agent guidance in Topic 606. Based on this assessment, the Company determined that WEX does not control the services performed by merchant acquirers, card networks and sponsor banks as each of these parties is the primary obligor for their portion of payment and transaction processing services performed. Therefore interchange income is recognized net of any fees owed to these intermediaries. The Company determined that services performed by third-party payment processors are controlled by WEX as the Company is responsible for directing how the third-party payment processor authorizes and processes transactions on the Company’s behalf. Therefore, such fees paid to third-party payment processors are recorded as service fees within cost of services. Additionally, the Company enters into contracts with certain large customers or strategic cardholders that provide for fee rebates tied to performance milestones. The Company considered whether such fee rebates constitute consideration payable to a customer or other parties that purchase services from the customer per Topic 606. If so, such fee rebates are recorded as a reduction in payment processing revenue in the same period that related interchange income is recognized. For the three months ended March 31, 2018, such variable consideration totaled approximately $198.5 million . Fee rebates made to certain other partners were determined to be costs to obtain a contract, and are recorded as sales and marketing expenses. Account Servicing Revenue In our Fleet Solutions segment, account servicing revenue is primarily comprised of monthly fees charged to cardholders based on the number of vehicles serviced. These fees are primarily in return for providing monthly vehicle data reports and are recognized on a monthly basis as the service is provided. Such revenue is outside of the scope of Topic 606, and continues to be accounted for under Topic 310. In our Travel and Corporate Solutions segment, account servicing reflects revenues earned from our accounts receivable and accounts payable SaaS platforms obtained as part of our recent AOC acquisition. In our Health and Employee Benefit Solutions segment, we also recognize account servicing fees for the per-participant per-month fee charged per consumer on our SaaS healthcare technology platform. Customers including health plans, third-party administrators, financial institutions and payroll companies typically enter into three to five year contracts, which contain significant termination penalties. Our primary performance obligation is a stand-ready commitment to provide SaaS services and support which is satisfied over time in a series of daily increments. Revenue is recognized based on an output method based using days elapsed to measure progress as the Company transfers control evenly over each monthly subscription period. Finance Fee Revenue The Company earns revenue on overdue accounts, which is recognized as revenue at the time the fees are assessed. The finance fee is calculated using the greater of a minimum charge or a stated late fee rate multiplied by the outstanding balance that is subject to a late fee charge. On occasion, these fees are waived to maintain customer goodwill. The established reserve for such waived amounts is estimated and offset against the late fee revenue recognized. The Company engages in factoring, which is the purchase of accounts receivable from a third-party at a discount. Revenue earned in this transaction is recorded in finance fees. The Company also recognizes finance fee revenue earned on the Company’s foreign salary advance product. All finance fees listed above are within the scope of Topic 310 and are recognized at the time of assessment. Other Revenue Other revenue includes transaction processing revenue, professional and marketing services and the sales of telematics hardware, all of which is within scope of Topic 606. Revenue is recognized when control of the services is transferred to our customers, in an amount that reflects the consideration that we expect to receive in exchange for those services. In addition, international settlement fees and certain other cardholder fees (e.g. replacement card fees) are included in other revenue. These cardholder fees are within the scope of Topic 310 and are recognized upon completion of the related service. Contract Balances The Company’s contract assets consist of upfront payments made to customers under long-term contracts and are recorded upon payment or when due. These payments reduce revenue recognition in future periods, as the resulting asset is amortized against revenue as the Company performs its obligations under these arrangements. The Company’s contract liabilities, which consist of upfront payments received from customers, are recorded as contract liabilities upon receipt or when due, and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. The following table provides information about these contract assets and liabilities from contracts with customers. Our contract assets and liabilities are reported in a net position on a contract-by-contract basis at the end of each reporting period. (In thousands) Contract balance Location on the unaudited condensed consolidated balance sheets March 31, 2018 Receivables 1 Accounts receivable, net $ 19,379 Contract assets Prepaid expenses and other current assets and Other assets $ 53,363 Contract liabilities Other current liabilities $ 23,841 1 The majority of the Company’s receivables, excluded from the table above, are either due from cardholders, who have not been deemed our customer as it relates to interchange income, or from revenues earned outside of the scope of ASC Topic 606. Impairment losses recognized on our receivables and contract assets were immaterial for the three months ended March 31, 2018 . In the three months ended March 31, 2018 , revenue recognized related to contract liabilities as of December 31, 2017 was immaterial. Remaining Performance Obligations The Company’s unsatisfied, or partially unsatisfied performance obligations as of March 31, 2018 represent the remaining minimum monthly fees on a portion of contracts across the lines of business and contractually obligated professional services yet to be provided by the Company. It is not indicative of the Company’s future revenue, as it relates to an insignificant portion of the Company’s operations. As allowed by Topic 606, the Company has elected to exclude from this disclosure the value of unsatisfied performance obligations for contracts with an original expected duration of one year or less. The following table includes revenue expected to be recognized in the future related to remaining performance obligations at the end of the reporting period. (In thousands) 2018 2019 2020 2021 2022 Thereafter Total Minimum monthly fees 1 $ 34,432 $ 30,814 $ 17,565 $ 9,719 $ 5,744 $ 267 $ 98,541 Professional services 2 12,840 2,363 — — — — 15,203 Total remaining performance obligations $ 47,272 $ 33,177 $ 17,565 $ 9,719 $ 5,744 $ 267 $ 113,744 1 The transaction price allocated to the remaining performance obligations represents the minimum monthly fees on certain service contracts, which contain substantive termination penalties that require the counterparty to pay the Company for the aggregate remaining minimum monthly fees upon an early termination for convenience. 2 Includes software development projects and other services sold subsequent to the core offerings, to which the customer is contractually obligated.

Business Acquisition

Business Acquisition	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Business Acquisition	4. Business Acquisition AOC Effective O ctober 18, 2017 , the Company acquired certain assets and assumed certain liabilities of AOC Solutions and one of its affiliate companies, 3Delta Systems, Inc. (collectively “AOC”), an industry leader in commercial payments technology. The acquisition of AOC, a longstanding technology provider for our virtual card product, will broaden our capabilities, increase our pool of employees with payments platform expertise and allow us to evolve with the needs of our customers and partners through the use of AOC’s payments processing technology platforms. The Company purchased AOC for $129.8 million , which was funded with cash on hand and through borrowings under the 2016 Credit Agreement. The Company records adjustments to the assets acquired and liabilities assumed throughout the measurement period, which may be up to one year from the acquisition date. The Company has obtained information to assist in determining the fair values of certain assets acquired and liabilities assumed since the acquisition, resulting primarily in the recording of other intangible assets and goodwill. Goodwill is calculated as the consideration in excess of net assets recognized and represents the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized, including synergies derived from the acquisition. The goodwill and intangible assets recorded from this business combination were assigned to our Travel and Corporate Solutions segment. The Company has not finalized the purchase accounting and is currently evaluating the tax basis and the allocation of book basis to the assets acquired and liabilities assumed in this business combination. Specifically, the Company is still reviewing the valuation as well as performing procedures to verify the completeness and accuracy of the data used in the independent valuation for intangible assets identified in the table below. Additionally, we are assessing the value of acquired in-process research and development software. The preliminary estimates could change significantly upon completion of this evaluation. The goodwill recognized in this business combination will be deductible for income tax purposes. The following is a summary of the preliminary allocation of the purchase price to the assets and liabilities acquired: (In thousands) As Reported December 31, 2017 Measurement Period Adjustments As Reported, March 31, 2018 Total consideration $ 129,828 $ — $ 129,828 Less: — Cash 15,546 — 15,546 Accounts receivable 4,171 — 4,171 Property and equipment 2,530 (1,329 ) 1,201 Customer relationships (a) 15,000 200 15,200 Developed technologies (b) 24,100 — 24,100 Trademarks and trade names (c) 1,460 10 1,470 Other liabilities (685 ) (449 ) (1,134 ) Recorded goodwill $ 67,706 $ 1,568 $ 69,274 (a) Weighted average life – 9.0 years . (b) Weighted average life – 3.4 years . (c) Weighted average life – 4.3 years . (a) (b) (c) The weighted average life of these amortized intangible assets is 5.5 years . Since the acquisition date, the operations of AOC contributed net revenues of approximately $6.7 million and net loss before taxes of approximately $0.6 million during the year ended December 31, 2017. No pro forma information has been included in these financial statements as the operations of AOC for the period that they were not part of the Company are not material to the Company’s revenues, net income and earnings per share.

Accounts Receivable

Accounts Receivable	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Accounts Receivable	5. Accounts Receivable In general, the Company’s trade receivables provide for payment terms of 30 days or less. Receivables not paid within the terms of the agreement are generally subject to late fees based upon the outstanding receivable balance. The Company extends revolving credit to certain small fleets. These accounts are also subject to late fees, and balances that are not paid in full are subject to interest charges based on the revolving balance. The Company had approximately $14.1 million and $12.2 million in receivables with revolving credit balances as of March 31, 2018 and December 31, 2017 , respectively. Concentration of Credit Risk The receivables portfolio consists of a large group of homogeneous smaller balances across a wide range of industries, which are collectively evaluated for impairment. No one third-party receivable represented 10 percent or more of the outstanding receivables balance at March 31, 2018 or December 31, 2017. The following table presents the outstanding balance of trade accounts receivable that are less than 30 and 60 days past due, in each case, as a percentage of total trade accounts receivable: March 31, 2018 December 31, 2017 Delinquency Status 29 days or less past due 96 % 95 % 59 days or less past due 98 % 97 % Reserves for Accounts Receivable Receivables are generally written off when they are 150 days past due or upon declaration of bankruptcy of the customer. The reserve for credit losses is calculated by an analytic model that also takes into account other factors, such as the actual charge-offs for the preceding reporting periods, expected charge-offs and recoveries for the subsequent reporting periods, a review of past due accounts receivable balances, changes in payment patterns, known fraudulent activity in the portfolio, as well as leading economic and market indicators. The following table presents changes in the accounts receivable allowances: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of year $ 30,207 $ 20,092 Provision for credit losses 13,990 12,231 Charges to other accounts 1 4,442 2,939 Charge-offs (19,221 ) (13,369 ) Recoveries of amounts previously charged-off 1,926 928 Currency translation 99 745 Balance, end of period $ 31,443 $ 23,566 1 The Company earns revenue by assessing monthly finance fees on accounts with overdue balances. These fees are recognized as revenue at the time the fees are assessed. The finance fee is calculated using the greater of a minimum charge or a stated late fee rate multiplied by the outstanding balance that is subject to a late fee charge. On occasion, these fees are waived to maintain relationship goodwill. Charges to other accounts represents the offset against the late fee revenue recognized when the Company establishes a reserve for such waived amounts.

Earnings per Share

Earnings per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings per Share	6. Earnings per Share Basic earnings per share is computed by dividing net income attributable to shareholders by the weighted average number of shares of common stock and vested deferred stock units outstanding during the year. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options, the assumed issuance of unvested restricted stock units and deferred stock units, and unvested performance-based restricted stock units for which the performance condition has been met as of the date of determination using the treasury stock method unless the effect is anti-dilutive. The treasury stock method assumes that proceeds, including cash received from the exercise of employee stock options and the average unrecognized compensation expense for unvested share-based compensation awards, would be used to purchase the Company’s common stock at the average market price during the period. The following table summarizes net income attributable to shareholders and reconciles basic and diluted shares outstanding used in the earnings per share computations: Three Months Ended March 31, (In thousands) 2018 2017 Net income attributable to shareholders $ 48,633 $ 29,401 Weighted average common shares outstanding – Basic 43,049 42,871 Dilutive impact of share-based compensation awards 401 248 Weighted average common shares outstanding – Diluted 43,450 43,119 For the three months ended March 31, 2018 and March 31, 2017 , an immaterial number of outstanding share-based compensation awards were excluded from the computation of diluted earnings per share, as the effect of including these awards would be anti-dilutive.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	7. Derivative Instruments The Company is exposed to certain market risks relating to its ongoing business operations. From time to time, the Company enters into derivative instrument arrangements to manage various risks including interest rate risk, foreign exchange risk and commodity price risk. Interest Rate Swap Agreements During 2016 and 2017, we entered into five interest rate swap contracts. Collectively, these derivative contracts are intended to fix the future interest payments associated with $1.3 billion of our variable rate borrowings at between 0.896% and 2.212% . At March 31, 2018 , we had variable-rate borrowings of $1.7 billion under our 2016 Credit Agreement. The notional amounts, fixed and variable interest rates and maturities of the interest rate swap agreements are as follows: Tranche A Tranche B Tranche C Tranche D Tranche E Notional amount at inception (in thousands) $300,000 $200,000 $400,000 $150,000 $250,000 Amortization N/A N/A 5% annually N/A N/A Maturity date 12/30/2022 12/30/2022 12/31/2020 12/31/2020 12/31/2018 Fixed interest rate 2.204% 2.212% 1.108% 1.125% 0.896% The following table presents information on the location and amounts of interest rate swap gains and losses: (In thousands) Three Months Ended March 31, Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income 1 2018 2017 Interest rate swap agreements – unrealized portion Net unrealized gains on interest rate swap agreements $ 13,508 $ 1,565 Interest rate swap agreements – realized portion Financing interest income (expense) $ 313 $ (543 ) 1 The Company has not elected hedge accounting treatment. See Note 11 , Fair Value, for more information regarding the valuation of the Company’s interest rate swaps. Foreign Currency Exchange Program The Company utilizes a limited foreign currency exchange hedging program, entering into short-term foreign currency swaps to convert the foreign currency exposures of certain foreign currency denominated intercompany loans and investments to the base currency. The Company will continue to monitor its foreign currency exposure for discrete items and may, from time to time, hedge certain foreign currency transactions. The following table summarizes the contracts related to the Company’s foreign currency swaps, which settle in the base currency at various dates within 5 days after quarter-end: Aggregate Notional Amount March 31, (In thousands) 2018 2017 Australian dollar A$ 5,000 A$ 18,000 The amount of gains and losses associated with foreign currency swaps were not material for the three months ended March 31, 2018 and March 31, 2017 .

Financing and Other Debt

Financing and Other Debt	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Financing and Other Debt	9. Financing and Other Debt The following table summarizes the Company’s total outstanding debt: (In thousands) March 31, 2018 December 31, 2017 Revolving line-of-credit facility under 2016 Credit Agreement (a) $ 1,000 $ 136,535 Term loans under 2016 Credit Agreement (a) 1,746,799 1,602,875 Notes outstanding (a) 400,000 400,000 Securitized debt 145,587 126,901 Participation debt 166,361 184,990 WEX Latin America debt 9,377 9,747 Total gross debt $ 2,469,124 $ 2,461,048 Current portion of gross debt $ 308,638 $ 404,233 Less: unamortized debt issuance costs (7,928 ) (7,015 ) Short-term debt, net $ 300,710 $ 397,218 Long-term gross debt $ 2,160,486 $ 2,056,815 Less: unamortized debt issuance costs (28,203 ) $ (29,063 ) Long-term debt, net $ 2,132,283 $ 2,027,752 Supplemental information under 2016 Credit Agreement: Letters of credit (b) $ 52,600 $ 27,500 Borrowing capacity $ 516,400 $ 405,965 (a) See Note 11 , Fair Value, for more information regarding the Company’s 2016 Credit Agreement and notes outstanding. (b) Collateral for lease agreements, virtual card and fuel payment processing activity at the Company’s foreign subsidiaries 2016 Credit Agreement The 2016 Credit Agreement provides for tranche A and tranche B term loan facilities in amounts equal to $455.0 million and $1,335.0 million respectively, and a $570.0 million secured revolving credit facility, with a sublimit for letters of credit and swingline loans. Under the 2016 Credit Agreement, amounts due under the revolving credit facility and the tranche A term loan facility mature in July 2021, while amounts due under the tranche B term loan facility mature in July 2023. Prior to maturity, amounts borrowed under the credit facility will be reduced by mandatory quarterly payments of $5.7 million and $3.4 million for tranche A and tranche B term loan facilities, respectively. On January 17, 2018, the Company repriced the secured term loans under the 2016 Credit Agreement, which reduced the applicable interest rate margin for the Company’s tranche B term loan facility by 50 basis points for both LIBOR borrowings and base rate borrowings and increased the outstanding amounts on these tranche B term loans from $1,182.0 million to $1,335.0 million . In addition, the repricing made certain other changes to the 2016 Credit Agreement, including increasing the maximum consolidated leverage ratio for both the period of December 31, 2018 through September 30, 2019, and upon the occurrence of an acquisition meeting certain specified criteria, permitting the incurrence of unsecured indebtedness as long as the Company is in pro forma compliance with the financial covenants, resetting the six month soft call period for a repricing of the tranche B term loans and resetting and amending the test for incremental loans. Following the repricing, the applicable interest rate margin for the tranche B term loans was set at 2.3% for LIBOR borrowings and 1.25% for base rate borrowings. After giving effect to the January 2018 repricing, amounts outstanding under the 2016 Credit Agreement bear interest at a rate equal to, at the Company’s option, (a) the Eurocurrency Rate, as defined in the 2016 Credit Agreement, plus a margin of between 1.75% to 3.25% ( 2.25% at March 31, 2018) with respect to the revolving credit facility, between 1.75% to 2.75% ( 2.00% at March 31, 2018) with respect to the tranche A term loan facility, and 2.25% with respect to the tranche B term loan facility (with the Eurocurrency Rate subject to a 0.00% floor), in each case, based on the consolidated leverage ratio or (b) the highest of (i) the Federal Funds Rate plus 0.50% , (ii) the prime rate announced by Bank of America, and (iii) the Eurocurrency Rate plus 1.00% , in each case plus a margin of 0.75% to 2.25% ( 1.25% at March 31, 2018) with respect to the revolving credit facility, 0.75% to 1.75% ( 1.00% at March 31, 2018) with respect to the tranche A term loan facility and 1.75% with respect to the tranche B term loan facility, with the margin determined in the case of the revolving credit facility and the tranche A term loan facility based on the consolidated leverage ratio. As of March 31, 2018 and December 31, 2017 , amounts outstanding under the 2016 Credit Agreement bore a weighted average effective interest rate of 4.1 percent and 4.2 percent , respectively. The Company accounted for the January 2018 repricing as both a debt extinguishment and debt modification by evaluating the refinancing on a creditor by creditor basis. The Company recorded a loss on extinguishment of debt of $1.1 million related to the write-off of unamortized debt issuance costs and incurred general and administrative expenses of $3.0 million related to third-party costs associated with the modified debt. The loss on extinguishment and third-party costs are reflected as financing interest expense and service fees, respectively, within our unaudited condensed consolidated statements of income. In addition, the Company incurred and capitalized $2.9 million of new debt issuance costs related to the repricing. The Company maintains interest rate swap agreements to manage the interest rate risk associated with its outstanding variable-interest rate borrowings under the 2016 Credit Agreement. See Note 7 , Derivative Instruments, for further discussion. Debt Covenants As more fully described in the Company’s Annual Report on Form 10–K for the year ended December 31, 2017 , the 2016 Credit Agreement and the Indenture contain covenants that limit the ability of the Company and its subsidiaries, including its restricted subsidiaries and, in certain limited circumstances, WEX Bank and the Company’s other regulated subsidiaries, to (i) incur additional debt, (ii) pay dividends or make other distributions on, redeem or repurchase capital stock, or make investments or other restricted payments, (iii) enter into transactions with affiliates, (iv) dispose of assets or issue stock of restricted subsidiaries or regulated subsidiaries, (v) create liens on assets, or (vi) effect a consolidation or merger or sell all, or substantially all, of the Company’s assets. As of March 31, 2018 , the Company was in compliance with all material covenants of its 2016 Credit Agreement and the Indenture. Notes Outstanding As of both March 31, 2018 and December 31, 2017 , the Company had $400.0 million of 4.75% fixed-rate senior notes outstanding, which will mature on February 1, 2023. Interest is payable semiannually in arrears on February 1 and August 1 of each year, commencing on August 1, 2013. Australian Securitization Facility The Company has entered into a one year securitized debt agreement with the Bank of Tokyo-Mitsubishi UFJ, Ltd expiring April 2018. Subsequent to March 31, 2018, this agreement was extended through April 2019. Under the terms of the agreement, each month, on a revolving basis, the Company sells certain of its Australian receivables to the Company’s Australian Securitization Subsidiary. The Australian Securitization Subsidiary, in turn, uses the receivables as collateral to issue asset-backed commercial paper (“securitized debt”) for approximately 85 percent of the securitized receivables. The amount collected on the securitized receivables is restricted to pay the securitized debt and is not available for general corporate purposes. The Company pays a variable interest rate on the outstanding balance of the securitized debt, based on the Australian Bank Bill Rate plus an applicable margin. The interest rate was 2.68% and 2.53% as of March 31, 2018 and December 31, 2017 , respectively. The Company had $90.4 million and $90.0 million of securitized debt under this facility as of March 31, 2018 and December 31, 2017 , respectively. WEX Latin America Securitization Facility During the second quarter of 2017, WEX Latin America entered into a securitized debt agreement to sell certain unsecured receivables associated with our salary payment card product to an investment fund managed by an unrelated third-party financial institution. Under the terms of the agreement, the investment fund’s purchase price incorporates a discount relative to the face value of the transferred receivables. This securitization arrangement does not meet the derecognition conditions and accordingly WEX Latin America continues to report the transferred receivables in our unaudited condensed consolidated balance sheets with no change in the basis of accounting. Additionally, we recognize the cash proceeds received from the investment fund and record offsetting securitized debt in our unaudited condensed consolidated balance sheets. During the three months ended March 31, 2018, WEX Latin America paid $2.3 million in exchange for a non-controlling equity investment in the securitization facility. This equity investment is recorded within other assets in our unaudited condensed consolidated balance sheets. The Company had $31.6 million and $19.0 million of securitized debt under this facility as of March 31, 2018 and December 31, 2017, respectively. During the three months ending March 31, 2018, the Company recognized approximately $2.1 million of operating interest under this financing arrangement. European Securitization Facility On April 7, 2016, the Company entered into a five -year securitized debt agreement with the Bank of Tokyo-Mitsubishi UFJ, Ltd. Under the terms of the agreement, the Company sells certain of its receivables from selected European countries to its European Securitization Subsidiary. The European Securitization Subsidiary, in turn, uses the receivables as collateral to issue securitized debt. The amount collected on the securitized receivables is restricted to pay the securitized debt and is not available for general corporate purposes. The amounts of receivables to be securitized under this agreement will be determined by management on a monthly basis. The interest rate was 0.30 percent and 1.11 percent as of March 31, 2018 and December 31, 2017 , respectively. The Company had $23.5 million and $17.9 million of securitized debt under this facility as of March 31, 2018 and December 31, 2017 , respectively. Participation Debt WEX Bank maintains agreements with third-party banks to fund customer balances that exceed WEX Bank’s lending limit to an individual customer. Associated unsecured borrowings carry a variable interest rate of 1 month to 3 month LIBOR plus a margin of 225 basis points. The balance of the debt was approximately $166.4 million and $185.0 million at March 31, 2018 and December 31, 2017 , respectively. The balance will fluctuate on a daily basis based on customer funding needs. The commitment will mature in amounts of $85.0 million and $50.0 million on May 30, 2018 and December 31, 2021, respectively, with the remaining $31.4 million maturing on demand. WEX Latin America Debt WEX Latin America had debt of approximately $9.4 million and $9.7 million as of March 31, 2018 and December 31, 2017 , respectively. This is comprised of credit facilities and loan arrangements related to our accounts receivable. The average interest rate was 16.2 percent and 21.2 percent as of March 31, 2018 and December 31, 2017 , respectively. These borrowings are recorded in short-term debt, net on the Company’s unaudited condensed consolidated balance sheets for the periods presented.

Deposits and Borrowed Federal F

Deposits and Borrowed Federal Funds	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Deposits and Borrowed Funds	8. Deposits and Borrowed Federal Funds WEX Bank has issued certificates of deposit with maturities ranging from six months to three years, with interest rates ranging from 1.15% to 2.55% as of March 31, 2018 and from 1.00% to 2.15% as of December 31, 2017. WEX Bank may issue brokered deposits, subject to FDIC rules governing minimum financial ratios, which include risk-based asset and capital requirements. As of March 31, 2018 , all brokered deposits were in denominations of $250 thousand or less, corresponding to FDIC deposit insurance limits. The Company requires deposits from certain customers as collateral for credit that has been extended. These deposits are generally non-interest bearing. Interest-bearing money market deposits are issued in denominations of $250 thousand or less, and pay interest at variable rates based on LIBOR or the Federal Funds rate. Money market deposits may be withdrawn by the holder at any time, although notification may be required and the monthly number of transactions is limited. Interest-bearing money market deposits and customer deposits are classified as short-term deposits on our unaudited condensed consolidated balance sheets. The following table presents the composition of deposits: (In thousands) March 31, 2018 December 31, 2017 Interest-bearing money market deposits $ 258,204 $ 285,899 Customer deposits 69,531 70,211 Certificates of deposit with maturities within 1 year (a) 451,123 630,879 Short-term deposits 778,858 986,989 Certificates of deposit with maturities greater than 1 year and less than 5 years (a) 330,043 306,865 Total deposits $ 1,108,901 $ 1,293,854 Weighted average cost of funds on certificates of deposit outstanding 1.79 % 1.51 % Weighted average cost of interest-bearing money market deposits 1.80 % 1.49 % (a) Certificates of deposit are classified as short-term or long-term within our unaudited condensed consolidated balance sheets based on maturity date. Sources of Funds WEX Bank participates in the Insured Cash Sweep (“ICS”) service offered by Promontory Interfinancial Network, which allows WEX Bank to purchase brokered money market demand accounts and demand deposit accounts in an amount not to exceed $125.0 million . At March 31, 2018, the Company has made no such purchases. Borrowed Federal Funds WEX Bank borrows from lines of credit on a federal funds rate basis to supplement the financing of its accounts receivable. There were no borrowings against these lines of credit as of March 31, 2018 and December 31, 2017 . As of March 31, 2018, the Company’s federal funds available lines of credit was $275.0 million . Effective April 1, 2018, these available lines of credit were reduced to $150.0 million .

Off-Balance Sheet Arrangements

Off-Balance Sheet Arrangements	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Off-Balance Sheet Arrangements	10. Off–Balance Sheet Arrangement WEX Europe Services Accounts Receivable Factoring During the first quarter of 2017, WEX Europe Services entered into a factoring arrangement with an unrelated third-party financial institution (the “Purchasing Bank”) to sell certain of its accounts receivable in order to accelerate the collection of the Company’s cash and reduce internal costs, thereby improving liquidity. Under this arrangement, the Purchasing Bank establishes a credit limit for each customer account. The factored receivables are without recourse to the extent that the customer balances are maintained at or below the established credit limit. For customer receivable balances in excess of the Purchasing Bank’s credit limit, the Company maintains the risk of default. The Company obtained a true sale opinion from an independent attorney, which states that the factoring agreement creates a sale of receivables under local law for amounts transferred both below and above the established credit limits. Additionally, there are no indications of the Company’s continuing involvement in the factored receivables. As a result, the Purchasing Bank is deemed the purchaser of these receivables and is entitled to enforce payment of these amounts from the debtor. This factoring arrangement is accounted for as a sale and accordingly the Company records the receivables sold as a reduction of accounts receivable and proceeds as cash provided by operating activities. The Company sold approximately $170.2 million of receivables under this arrangement during the three months ended March 31, 2018 . Proceeds received are recorded net of applicable expenses, interest and commissions. The loss on factoring was $1.1 million for the three months ended March 31, 2018 and immaterial for the three months ended March 31, 2017 , and was recorded within cost of services in the unaudited condensed consolidated statements of income. As of March 31, 2018 , the Company had associated factoring receivables of approximately $30.3 million , of which approximately $0.5 million were in excess of the established credit limit. Charge-backs on balances in excess of the credit limit during the three months ended March 31, 2018 were insignificant. There were no charge-backs on balances in excess of the credit limit during the three months ended March 31, 2017.

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value	11. Fair Value The Company holds mortgage-backed securities, fixed-income securities, derivatives (see Note 7 , Derivative Instruments) and certain other financial instruments that are carried at fair value. The Company determines fair value based upon quoted prices when available or through the use of alternative approaches, such as model pricing, when market quotes are not readily accessible or available. Various factors are considered in determining the fair value of the Company’s obligations, including: closing exchange or over-the-counter market price quotations; time value and volatility factors underlying options and derivatives; price activity for equivalent instruments; and the Company’s own credit standing. These valuation techniques may be based upon observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s market assumptions. These two types of inputs create the following fair value hierarchy: • Level 1 – Quoted prices for identical instruments in active markets. • Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations whose inputs are observable or whose significant value drivers are observable. • Level 3 – Instruments whose significant value drivers are unobservable. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. We did not have any transfers between Level 1 and Level 2 of the fair value hierarchy during either of the three months ended March 31, 2018 or March 31, 2017 . The following table presents the Company’s assets and liabilities that are measured at fair value and the related hierarchy levels: (In thousands) Fair Value Hierarchy March 31, 2018 December 31, 2017 Assets Municipal bonds 2 $ 472 $ 534 Asset-backed securities 2 337 345 Mortgage-backed securities 2 300 305 Fixed-income mutual fund 1 21,940 22,174 Investment securities (a) $ 23,049 $ 23,358 Executive deferred compensation plan trust (b) 1 $ 7,565 $ 6,798 Interest rate swaps (c) 2 $ 32,059 $ 19,595 Liabilities Interest rate swaps (d) 2 $ 4,329 $ 5,373 (a) Not deemed available for current operations and have been classified as long-term assets. (b) The fair value of these instruments is recorded in other assets. (c) The fair value of these instruments is recorded in prepaid expenses and other current assets or other assets depending on the timing of expected discounted cash flows. (d) The fair value of these instruments is recorded in other current liabilities based on the timing of expected discounted cash flows. Investment Securities When available, the Company uses quoted market prices to determine the fair value of investment securities; such inputs are classified as Level 1 of the fair-value hierarchy. These securities primarily consist of an open-ended mutual fund which is invested in fixed-income securities and is held in order to satisfy the regulatory requirements of WEX Bank. For mortgage-backed and asset-backed debt securities and municipal bonds, the Company generally uses quoted prices for recent trading activity of assets with similar characteristics to the debt security or bond being valued. The securities and bonds priced using such methods are generally valued using Level 2 inputs. Executive Deferred Compensation Plan Trust The obligations related to the deferred compensation plan trust are classified as Level 1 in the fair value hierarchy because the fair value is determined using quoted prices for identical instruments in active markets. Interest Rate Swaps The Company determines the fair value of its interest rate swaps based on the discounted cash flows of the difference between the projected fixed payments on the swaps and the implied floating payments using the current LIBOR curve, which are Level 2 inputs of the fair value hierarchy. Notes Outstanding The Notes outstanding had a fair value of $402.0 million and $410.0 million as of March 31, 2018 and December 31, 2017 , respectively. The fair value of the Notes, which is recorded in long-term debt, net, is based on market rates for the issuance of our debt and is classified as Level 2 in the fair value hierarchy. 2016 Credit Agreement The Company determines the fair value of the amount outstanding under its 2016 Credit Agreement based on the market rates for the issuance of the Company’s debt, which are Level 2 inputs in the fair value hierarchy. As of both March 31, 2018 and December 31, 2017 , the carrying value of the 2016 Credit Agreement approximated its fair value.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes The Company’s effective tax rate was 24.0 percent for the first quarter of 2018 as compared to 33.3 percent for the first quarter of 2017. The decline in our tax rate was primarily due to the 2017 Tax Act, which reduced the U.S. federal corporate income tax rate from 35 percent to 21 percent effective January 1, 2018. During the fourth quarter of 2017, the Company recorded a provisional amount of one-time income tax benefit of $60.6 million associated with the 2017 Tax Act and it has not changed at March 31, 2018. This estimate may be impacted by further analysis and future clarification and guidance regarding available tax accounting methods and elections, earnings and profits computations and state tax conformity to federal tax changes. As of March 31, 2018, we are still evaluating the effects of the Global Intangible Low Taxed Income (“GILTI”) provisions as guidance and interpretations continue to emerge. However, we do not expect the impact to be material to our financial statements. We have not determined the accounting policy of either treating taxes due on future U.S. inclusions in taxable income related to GILTI as a current period expense when incurred, or factoring such amounts into the Company’s measurement of its deferred taxes. However, the standard requires that we reflect the impact of the GILTI provisions as a period expense until the accounting policy is finalized. Therefore, we have included the provisional estimate of GILTI related to current year operations in our estimated annual effective tax rate and will update the impact and accounting policy as the analysis related to the GILTI provisions is completed. Undistributed earnings of certain foreign subsidiaries of the Company amounted to $73.4 million and $58.7 million at March 31, 2018 and December 31, 2017 , respectively. These earnings are considered to be indefinitely reinvested. For the period ending March 31, 2018, except for GILTI, as indicated above, the Company did not record United States federal income tax on its share of the income of its foreign subsidiaries. Upon distribution of these earnings in the form of dividends or otherwise, the Company would be subject to withholding taxes payable, where applicable, to foreign countries, and to certain state income taxes, but would have no further federal income tax liability.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	13. Commitments and Contingencies Litigation The Company is subject to legal proceedings and claims in the ordinary course of business. As of the date of this filing, the current estimate of a reasonably possible loss contingency from all legal proceedings is not material to the Company’s consolidated financial position, results of operations, cash flows or liquidity. Commitments Significant commitments and contingencies as of March 31, 2018 are consistent with those discussed in Note 18, Commitments and Contingencies, to the consolidated financial statements in the Annual Report on Form 10–K for the year ended December 31, 2017 .

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	14. Stock–Based Compensation The fair value of restricted stock units, deferred stock units, performance-based restricted stock units and service-based stock options awarded during the three months ended March 31, 2018 totaled $27.4 million , as compared to $28.1 million for the three months ended March 31, 2017 . The fair value of restricted stock units, deferred stock units and performance-based restricted stock units is based on the closing market price of the Company’s stock on the grant date as reported by the NYSE. The fair value of each service-based option award is estimated on the grant date using a Black-Scholes-Merton option-pricing model. The table below summarizes the assumptions used to calculate the fair value of service-based stock options by year of grant: 2018 2017 Weighted average expected life (in years) 6.0 6.0 Weighted average exercise price $ 158.23 $ 104.95 Weighted average volatility 27.35 % 30.67 % Weighted average risk-free rate 2.69 % 2.13 % Weighted average fair value $ 51.27 $ 35.58

Restructuring Activities

Restructuring Activities	3 Months Ended
	Mar. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring Activities	15. Restructuring Activities Restructuring In the first quarter of 2015, the Company commenced a restructuring initiative (the “2015 Restructuring Initiative”) as a result of its global review of operations. The review of operations identified certain initiatives to further streamline the business, improve the Company’s efficiency and globalize the Company’s operations, all with an objective to improve scale and increase profitability going forward. The Company continued its efforts to improve its overall operational efficiency and began a second restructuring initiative (the “2016 Restructuring Initiative”) during the second quarter of 2016. In connection with the EFS acquisition, the Company initiated a third restructuring program in the third quarter of 2016 (the “Acquisition Integration Restructuring Initiative”). The restructuring expenses related to these initiatives primarily consist of employee costs and office closure costs directly associated with the respective programs. The Company has determined the amount of expenses related to these initiatives is probable and reasonably estimable. As such, the Company has recorded the impact on the unaudited condensed consolidated statements of income and in accrued expenses and other liabilities on the unaudited condensed consolidated balance sheets. Restructuring charges incurred to date under these initiatives were $24.7 million as of March 31, 2018 . The balances under these initiatives are expected to be paid through 2018 and are included in current liabilities at March, 31, 2018 and December 31, 2017. Based on current plans, which are subject to change, the amount of additional restructuring costs that the Company expects to incur is immaterial. The following table presents the Company’s 2015 Restructuring Initiative liability: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of period $ 2,680 $ 5,231 Restructuring charges — 310 Reserve release (14 ) — Cash paid (409 ) (348 ) Impact of foreign currency translation 80 38 Balance, end of period $ 2,337 $ 5,231 The following table presents the Company’s 2016 Restructuring Initiative liability: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of period $ 738 $ 3,662 Reserve release (4 ) (533 ) Cash paid (315 ) — Impact of foreign currency translation 19 73 Balance, end of period $ 438 $ 3,202 The following table presents the Company’s Acquisition Integration Restructuring Initiative liability: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of period $ 5,093 $ 1,764 Restructuring charges 1 185 707 Cash paid (5,101 ) (590 ) Other 22 258 Impact of foreign currency translation 2 — Balance, end of period $ 201 $ 2,139 1 Primarily consists of office closure costs. The following table presents the Company’s total restructuring liability: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of period $ 8,511 $ 10,657 Restructuring charges 185 1,017 Reserve release (18 ) (533 ) Cash paid (5,825 ) (938 ) Other 22 258 Impact of foreign currency translation 101 111 Balance, end of period $ 2,976 $ 10,572

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Segment Information	16. Segment Information Operating segments are defined as components of an enterprise about which separate financial information is available and is evaluated regularly by the chief operating decision maker (“CODM”) in deciding how to allocate resources and assess performance. The Company’s CODM is its Chief Executive Officer. The operating segments are aggregated into the three reportable segments described below. • Fleet Solutions provides customers with payment and transaction processing services specifically designed for the needs of commercial and government fleets. This segment also provides information management services to these fleet customers. • Travel and Corporate Solutions focuses on the complex payment environment of business-to-business payments, providing customers with payment processing solutions for their corporate payment and transaction monitoring needs. • Health and Employee Benefit Solutions provides healthcare payment products and SaaS consumer directed platforms, as well as payroll related benefits to customers. The following tables present the Company’s reportable segment results: Three Months Ended March 31, 2018 (In thousands) Fleet Solutions Travel and Corporate Solutions Health and Employee Benefit Solutions Total Revenues Payment processing revenue $ 106,978 $ 44,777 $ 16,699 $ 168,454 Account servicing revenue 42,210 9,469 27,025 78,704 Finance fee revenue 43,604 259 5,819 49,682 Other revenue 37,573 12,274 8,142 57,989 Total revenues $ 230,365 $ 66,779 $ 57,685 $ 354,829 Interest income $ 995 $ 421 $ 6,768 $ 8,184 Three Months Ended March 31, 2017 (In thousands) Fleet Solutions Travel and Corporate Solutions Health and Employee Benefit Solutions Total Revenues Payment processing revenue $ 86,262 $ 34,875 $ 15,241 $ 136,378 Account servicing revenue 36,069 155 25,315 61,539 Finance fee revenue 36,429 223 6,720 43,372 Other revenue 32,063 12,460 5,545 50,068 Total revenues $ 190,823 $ 47,713 $ 52,821 $ 291,357 Interest income $ 1,124 $ 46 $ 6,859 $ 8,029 In evaluating the financial performance of each segment, the CODM reviews segment adjusted operating income, which excludes: (i) acquisition and divestiture related items (including acquisition-related intangible amortization); (ii) debt restructuring costs; (iii) stock-based compensation; (iv) restructuring and other costs. Additionally, we do not allocate foreign currency gains and losses, financing interest expense, unrealized and realized gains and losses on derivative instruments, income taxes and net gains or losses from non-controlling interest to our operating segments. Effective January 1, 2018, the Company revised how it allocates certain costs in its measure of segment adjusted operating income. The primary change is how the Company allocates information technology and corporate related costs to its segments. Certain information technology and corporate related costs that support multiple segments, which were previously included in Fleet Solutions, are now being allocated to the segment that they support. Certain residual unallocated corporate costs represent the portion of expenses relating to general corporate functions including acquisition expenses, certain finance, legal, information technology, human resources, administrative and executive expenses and other expenses. These expenses are recorded in unallocated corporate expenses, as these items are centrally and directly controlled and are not included in internal measures of segment operating performance. Segment results for the three months ended March 31, 2017 have been recast to conform to the current presentation as described above. The following table reconciles segment adjusted operating income to income before income taxes: Three Months Ended March 31, (In thousands) 2018 2017 Segment adjusted operating income Fleet Solutions $ 101,908 $ 83,983 Travel and Corporate Solutions 25,249 19,186 Health and Employee Benefit Solutions 18,639 18,199 Total segment adjusted operating income $ 145,796 $ 121,368 Reconciliation: Total segment adjusted operating income $ 145,796 $ 121,368 Less: Unallocated corporate expenses 13,920 12,298 Acquisition–related intangible amortization 35,236 37,978 Other acquisition and divestiture related items 637 2,136 Debt restructuring costs 3,015 — Stock–based compensation 8,955 6,457 Restructuring and other costs 5,671 1,747 Operating income 78,362 60,752 Financing interest expense (27,337 ) (27,148 ) Net foreign currency gain 390 8,442 Net unrealized gains on interest rate swap agreements 13,508 1,565 Income before income taxes $ 64,923 $ 43,611

Supplementary Regulatory Capita

Supplementary Regulatory Capital Disclosure	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Supplementary Regulatory Capital Disclosure	17. Supplementary Regulatory Capital Disclosure The Company’s subsidiary, WEX Bank, is subject to various regulatory capital requirements administered by the FDIC and the Utah Department of Financial Institutions. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, WEX Bank must meet specific capital guidelines that involve quantitative measures of WEX Bank’s assets, liabilities, and certain off-balance sheet items. WEX Bank’s capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings and other factors. Failure to meet minimum capital requirements can result in the initiation of certain mandatory and possible additional discretionary actions by regulators that, if undertaken, could limit our business activities and have a material adverse effect on our business, results of operations and financial condition. As of March 31, 2018 and December 31, 2017, WEX Bank met all the requirements to be deemed “well-capitalized” pursuant to FDIC regulation and for purposes of the Federal Deposit Insurance Act. WEX Bank’s actual and regulatory minimum capital amounts and ratios are presented in the following table: (In thousands) Actual Amount Ratio Minimum for Capital Adequacy Purposes Amount Ratio Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount Ratio March 31, 2018 Total Capital to risk-weighted assets $ 311,040 12.80 % $ 194,418 8.0 % $ 243,023 10.0 % Tier 1 Capital to average assets $ 298,226 11.32 % $ 105,341 4.0 % $ 131,676 5.0 % Common equity to risk-weighted assets $ 298,226 12.27 % $ 109,360 4.5 % $ 157,965 6.5 % Tier 1 Capital to risk-weighted assets $ 298,226 12.27 % $ 145,814 6.0 % $ 194,418 8.0 % December 31, 2017 Total Capital to risk-weighted assets $ 316,129 13.38 % $ 188,991 8.0 % $ 236,239 10.0 % Tier 1 Capital to average assets $ 304,555 12.50 % $ 97,452 4.0 % $ 121,815 5.0 % Common equity to risk-weighted assets $ 304,555 12.89 % $ 106,308 4.5 % $ 153,555 6.5 % Tier 1 Capital to risk-weighted assets $ 304,555 12.89 % $ 141,743 6.0 % $ 188,991 8.0 %

Recent Accounting Pronounceme27

Recent Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Basis of Presentation	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10–Q and Rule 10–01 of Regulation S–X. Accordingly, they do not include all information and notes required by GAAP for complete financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the financial statements that are included in the Company’s Annual Report on Form 10–K for the year ended December 31, 2017 , filed with the SEC on March 1, 2018 . In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2018 are not necessarily indicative of the results for any future periods or the year ending December 31, 2018 . The Company rounds amounts in the unaudited condensed consolidated financial statements to thousands and calculates all per-share data from underlying whole-dollar amounts. Thus, certain amounts may not foot, crossfoot or recalculate based on reported numbers due to rounding.
New Accounting Standards	Standard Description Date/Method of Adoption Effect on financial statements or other significant matters Adopted During the Three Months Ended March 31, 2018 ASU 2014–09 This standard supersedes most existing revenue recognition guidance under GAAP. The new revenue recognition standard requires entities to recognize revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In addition, the standard requires disclosure of the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The Company adopted this standard on January 1, 2018. The guidance permits two methods of adoption: full retrospective approach, which requires an entity to restate each prior period that is reported in the financial statements and modified retrospective approach, which requires a cumulative adjustment to retained earnings as of the effective date, without restatement of prior period amounts. The Company adopted the standard using the modified retrospective method, applied to those contracts which were not completed as of January 1, 2018. The Company’s revenue from discount and interchange, transaction processing and certain fees is within the scope of Topic 606. FASB and its Transition Resource Group have issued clarifications on various aspects of ASU 2014–09. There were three primary impacts to the Company resulting from the adoption of Topic 606, which are described below. As of January 1, 2018, we recorded $0.6 million cumulative-effect adjustment, net of the associated tax effect, related to the deferral of capitalizable costs to obtain a contract within our Health and Employee Benefit Solutions segment. These commissions are amortized to sales and marketing expense over a useful life that considers the contract term, our commission policy, renewal experience and the transfer of services to which the asset relates. ASU 2017–07 This standard changes the presentation of net benefit pension costs by requiring the disaggregation of certain of its components. Under the guidance, companies are required to present the service cost component in the same income statement line item(s) as other employee compensation costs arising from services rendered during the period. The other components of net benefit cost will be presented in the income statement separately from the service cost component and outside the subtotal of operating income, if one is presented. Additionally, only the service cost component will be eligible for capitalization under the new guidance. The Company adopted ASU 2017–07 effective January 1, 2018. The adoption did not have a material impact on our results of operations, cash flows or consolidated financial position. ASU 2016–18 This standard clarifies the classification and presentation of restricted cash in the statement of cash flows. The statement of cash flows must explain the change during the period in the total of cash and cash equivalents and amounts described as restricted cash or cash equivalents. The Company retrospectively adopted ASU 2016–18 effective January 1, 2018. This retrospective adoption resulted in including restricted cash in cash, cash equivalents and restricted cash when reconciling the beginning of year and end of year amounts presented on the unaudited condensed consolidated statements of cash flows. A reconciliation of cash, cash equivalents and restricted cash as reported within our unaudited condensed consolidated balance sheets is included within our unaudited condensed consolidated statements of cash flows. ASU 2016–01 This standard requires equity investments, except those accounted for under the equity method of accounting, or those that result in consolidation of the investee, to be measured at fair value with changes in fair value recognized in net income. The Company adopted ASU 2016–01 effective All gains and losses on investment securities are now reflected as non-operating income within our unaudited condensed consolidated statements of income. The adoption did not have a material impact on our results of operations, balance sheet or cash flows. Not Yet Adopted as of March 31, 2018 ASU 2016–02 Leases (Topic 842) This standard increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. Certain qualitative and quantitative disclosures are required. The standard is effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period. When transitioning, the standard requires leases to be recognized and measured at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the impact the standard will have on the consolidated financial statements and related disclosures. ASU 2016–13 Financial Instruments–Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This standard requires financial assets measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of expected credit losses will be based on historical experience, current conditions, and reasonable and supportable forecasts that impact the collectability of the reported amount. The standard is effective for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. The Company is evaluating the impact the standard will have on the consolidated financial statements and related disclosures.
Receivables	In general, the Company’s trade receivables provide for payment terms of 30 days or less. Receivables not paid within the terms of the agreement are generally subject to late fees based upon the outstanding receivable balance. The Company extends revolving credit to certain small fleets. These accounts are also subject to late fees, and balances that are not paid in full are subject to interest charges based on the revolving balance.
Earnings per Share	Basic earnings per share is computed by dividing net income attributable to shareholders by the weighted average number of shares of common stock and vested deferred stock units outstanding during the year. The computation of diluted earnings per share is similar to the computation of basic earnings per share, except that the denominator is increased for the assumed exercise of dilutive options, the assumed issuance of unvested restricted stock units and deferred stock units, and unvested performance-based restricted stock units for which the performance condition has been met as of the date of determination using the treasury stock method unless the effect is anti-dilutive. The treasury stock method assumes that proceeds, including cash received from the exercise of employee stock options and the average unrecognized compensation expense for unvested share-based compensation awards, would be used to purchase the Company’s common stock at the average market price during the period.
Derivative Instruments	The Company is exposed to certain market risks relating to its ongoing business operations. From time to time, the Company enters into derivative instrument arrangements to manage various risks including interest rate risk, foreign exchange risk and commodity price risk.
Fair Value of Financial Instruments	Investment Securities When available, the Company uses quoted market prices to determine the fair value of investment securities; such inputs are classified as Level 1 of the fair-value hierarchy. These securities primarily consist of an open-ended mutual fund which is invested in fixed-income securities and is held in order to satisfy the regulatory requirements of WEX Bank. For mortgage-backed and asset-backed debt securities and municipal bonds, the Company generally uses quoted prices for recent trading activity of assets with similar characteristics to the debt security or bond being valued. The securities and bonds priced using such methods are generally valued using Level 2 inputs. Executive Deferred Compensation Plan Trust The obligations related to the deferred compensation plan trust are classified as Level 1 in the fair value hierarchy because the fair value is determined using quoted prices for identical instruments in active markets. Interest Rate Swaps The Company determines the fair value of its interest rate swaps based on the discounted cash flows of the difference between the projected fixed payments on the swaps and the implied floating payments using the current LIBOR curve, which are Level 2 inputs of the fair value hierarchy. 2016 Credit Agreement The Company determines the fair value of the amount outstanding under its 2016 Credit Agreement based on the market rates for the issuance of the Company’s debt, which are Level 2 inputs in the fair value hierarchy. The fair value of the Notes, which is recorded in long-term debt, net, is based on market rates for the issuance of our debt and is classified as Level 2 in the fair value hierarchy. The Company holds mortgage-backed securities, fixed-income securities, derivatives (see Note 7 , Derivative Instruments) and certain other financial instruments that are carried at fair value. The Company determines fair value based upon quoted prices when available or through the use of alternative approaches, such as model pricing, when market quotes are not readily accessible or available. Various factors are considered in determining the fair value of the Company’s obligations, including: closing exchange or over-the-counter market price quotations; time value and volatility factors underlying options and derivatives; price activity for equivalent instruments; and the Company’s own credit standing. These valuation techniques may be based upon observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s market assumptions. These two types of inputs create the following fair value hierarchy: • Level 1 – Quoted prices for identical instruments in active markets. • Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations whose inputs are observable or whose significant value drivers are observable. • Level 3 – Instruments whose significant value drivers are unobservable. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability.
Segment Information	Operating segments are defined as components of an enterprise about which separate financial information is available and is evaluated regularly by the chief operating decision maker (“CODM”) in deciding how to allocate resources and assess performance. The Company’s CODM is its Chief Executive Officer. The operating segments are aggregated into the three reportable segments described below. • Fleet Solutions provides customers with payment and transaction processing services specifically designed for the needs of commercial and government fleets. This segment also provides information management services to these fleet customers. • Travel and Corporate Solutions focuses on the complex payment environment of business-to-business payments, providing customers with payment processing solutions for their corporate payment and transaction monitoring needs. • Health and Employee Benefit Solutions provides healthcare payment products and SaaS consumer directed platforms, as well as payroll related benefits to customers.

Recent Accounting Pronounceme28

Recent Accounting Pronouncements Recent Accounting Pronouncements (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The following table provides a brief description of accounting pronouncements adopted during the quarter and recent accounting pronouncements that could have a material effect on our financial statements: Standard Description Date/Method of Adoption Effect on financial statements or other significant matters Adopted During the Three Months Ended March 31, 2018 ASU 2014–09 This standard supersedes most existing revenue recognition guidance under GAAP. The new revenue recognition standard requires entities to recognize revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In addition, the standard requires disclosure of the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The Company adopted this standard on January 1, 2018. The guidance permits two methods of adoption: full retrospective approach, which requires an entity to restate each prior period that is reported in the financial statements and modified retrospective approach, which requires a cumulative adjustment to retained earnings as of the effective date, without restatement of prior period amounts. The Company adopted the standard using the modified retrospective method, applied to those contracts which were not completed as of January 1, 2018. The Company’s revenue from discount and interchange, transaction processing and certain fees is within the scope of Topic 606. FASB and its Transition Resource Group have issued clarifications on various aspects of ASU 2014–09. There were three primary impacts to the Company resulting from the adoption of Topic 606, which are described below. As of January 1, 2018, we recorded $0.6 million cumulative-effect adjustment, net of the associated tax effect, related to the deferral of capitalizable costs to obtain a contract within our Health and Employee Benefit Solutions segment. These commissions are amortized to sales and marketing expense over a useful life that considers the contract term, our commission policy, renewal experience and the transfer of services to which the asset relates. ASU 2017–07 This standard changes the presentation of net benefit pension costs by requiring the disaggregation of certain of its components. Under the guidance, companies are required to present the service cost component in the same income statement line item(s) as other employee compensation costs arising from services rendered during the period. The other components of net benefit cost will be presented in the income statement separately from the service cost component and outside the subtotal of operating income, if one is presented. Additionally, only the service cost component will be eligible for capitalization under the new guidance. The Company adopted ASU 2017–07 effective January 1, 2018. The adoption did not have a material impact on our results of operations, cash flows or consolidated financial position. ASU 2016–18 This standard clarifies the classification and presentation of restricted cash in the statement of cash flows. The statement of cash flows must explain the change during the period in the total of cash and cash equivalents and amounts described as restricted cash or cash equivalents. The Company retrospectively adopted ASU 2016–18 effective January 1, 2018. This retrospective adoption resulted in including restricted cash in cash, cash equivalents and restricted cash when reconciling the beginning of year and end of year amounts presented on the unaudited condensed consolidated statements of cash flows. A reconciliation of cash, cash equivalents and restricted cash as reported within our unaudited condensed consolidated balance sheets is included within our unaudited condensed consolidated statements of cash flows. ASU 2016–01 This standard requires equity investments, except those accounted for under the equity method of accounting, or those that result in consolidation of the investee, to be measured at fair value with changes in fair value recognized in net income. The Company adopted ASU 2016–01 effective All gains and losses on investment securities are now reflected as non-operating income within our unaudited condensed consolidated statements of income. The adoption did not have a material impact on our results of operations, balance sheet or cash flows. Not Yet Adopted as of March 31, 2018 ASU 2016–02 Leases (Topic 842) This standard increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. Certain qualitative and quantitative disclosures are required. The standard is effective for annual reporting periods beginning after December 15, 2018, including interim periods within that reporting period. When transitioning, the standard requires leases to be recognized and measured at the beginning of the earliest period presented using a modified retrospective approach. The Company is evaluating the impact the standard will have on the consolidated financial statements and related disclosures. ASU 2016–13 Financial Instruments–Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments This standard requires financial assets measured at amortized cost basis to be presented at the net amount expected to be collected. The measurement of expected credit losses will be based on historical experience, current conditions, and reasonable and supportable forecasts that impact the collectability of the reported amount. The standard is effective for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. The Company is evaluating the impact the standard will have on the consolidated financial statements and related disclosures.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Summary of Disaggregation of Revenue	The following table disaggregates our consolidated revenue: Three Months Ended March 31, 2018 (In thousands) Fleet Solutions Travel and Corporate Solutions Health and Employee Benefit Solutions Total Topic 606 revenues Payment processing revenue $ 106,978 $ 44,777 $ 16,699 $ 168,454 Account servicing revenue 8,466 9,469 27,025 44,960 Other revenue 17,042 1,117 8,142 26,301 Total Topic 606 revenues $ 132,486 $ 55,363 $ 51,866 $ 239,715 Topic 310 revenues Account servicing revenue $ 33,744 — — $ 33,744 Finance fee revenue 43,604 259 5,819 49,682 Other revenue 20,531 11,157 — 31,688 Total Topic 310 revenues $ 97,879 $ 11,416 $ 5,819 $ 115,114 Total revenues $ 230,365 $ 66,779 $ 57,685 $ 354,829
Summary of Contract Assets and Liabilities	The following table provides information about these contract assets and liabilities from contracts with customers. Our contract assets and liabilities are reported in a net position on a contract-by-contract basis at the end of each reporting period. (In thousands) Contract balance Location on the unaudited condensed consolidated balance sheets March 31, 2018 Receivables 1 Accounts receivable, net $ 19,379 Contract assets Prepaid expenses and other current assets and Other assets $ 53,363 Contract liabilities Other current liabilities $ 23,841 1 The majority of the Company’s receivables, excluded from the table above, are either due from cardholders, who have not been deemed our customer as it relates to interchange income, or from revenues earned outside of the scope of ASC Topic 606.
Schedule of Remaining Performance Obligations	The following table includes revenue expected to be recognized in the future related to remaining performance obligations at the end of the reporting period. (In thousands) 2018 2019 2020 2021 2022 Thereafter Total Minimum monthly fees 1 $ 34,432 $ 30,814 $ 17,565 $ 9,719 $ 5,744 $ 267 $ 98,541 Professional services 2 12,840 2,363 — — — — 15,203 Total remaining performance obligations $ 47,272 $ 33,177 $ 17,565 $ 9,719 $ 5,744 $ 267 $ 113,744 1 The transaction price allocated to the remaining performance obligations represents the minimum monthly fees on certain service contracts, which contain substantive termination penalties that require the counterparty to pay the Company for the aggregate remaining minimum monthly fees upon an early termination for convenience. 2 Includes software development projects and other services sold subsequent to the core offerings, to which the customer is contractually obligated.

Business Acquisition (Tables)

Business Acquisition (Tables)	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Schedule of Business Acquisitions	The following is a summary of the preliminary allocation of the purchase price to the assets and liabilities acquired: (In thousands) As Reported December 31, 2017 Measurement Period Adjustments As Reported, March 31, 2018 Total consideration $ 129,828 $ — $ 129,828 Less: — Cash 15,546 — 15,546 Accounts receivable 4,171 — 4,171 Property and equipment 2,530 (1,329 ) 1,201 Customer relationships (a) 15,000 200 15,200 Developed technologies (b) 24,100 — 24,100 Trademarks and trade names (c) 1,460 10 1,470 Other liabilities (685 ) (449 ) (1,134 ) Recorded goodwill $ 67,706 $ 1,568 $ 69,274 (a) Weighted average life – 9.0 years . (b) Weighted average life – 3.4 years . (c) Weighted average life – 4.3 years . (a) (b) (c) The weighted average life of these amortized intangible assets is 5.5 years .

Accounts Receivable (Tables)

Accounts Receivable (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Past Due Financing Receivables	The following table presents the outstanding balance of trade accounts receivable that are less than 30 and 60 days past due, in each case, as a percentage of total trade accounts receivable: March 31, 2018 December 31, 2017 Delinquency Status 29 days or less past due 96 % 95 % 59 days or less past due 98 % 97 %
Changes in Reserves for Credit Losses Related to Accounts Receivable	The following table presents changes in the accounts receivable allowances: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of year $ 30,207 $ 20,092 Provision for credit losses 13,990 12,231 Charges to other accounts 1 4,442 2,939 Charge-offs (19,221 ) (13,369 ) Recoveries of amounts previously charged-off 1,926 928 Currency translation 99 745 Balance, end of period $ 31,443 $ 23,566 1 The Company earns revenue by assessing monthly finance fees on accounts with overdue balances. These fees are recognized as revenue at the time the fees are assessed. The finance fee is calculated using the greater of a minimum charge or a stated late fee rate multiplied by the outstanding balance that is subject to a late fee charge. On occasion, these fees are waived to maintain relationship goodwill. Charges to other accounts represents the offset against the late fee revenue recognized when the Company establishes a reserve for such waived amounts.

Earnings per Share (Tables)

Earnings per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Reconciliation of Income and Share Data Used in Basic and Diluted Earnings Per Share Computations	The following table summarizes net income attributable to shareholders and reconciles basic and diluted shares outstanding used in the earnings per share computations: Three Months Ended March 31, (In thousands) 2018 2017 Net income attributable to shareholders $ 48,633 $ 29,401 Weighted average common shares outstanding – Basic 43,049 42,871 Dilutive impact of share-based compensation awards 401 248 Weighted average common shares outstanding – Diluted 43,450 43,119

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts of Outstanding Derivative Positions	The notional amounts, fixed and variable interest rates and maturities of the interest rate swap agreements are as follows: Tranche A Tranche B Tranche C Tranche D Tranche E Notional amount at inception (in thousands) $300,000 $200,000 $400,000 $150,000 $250,000 Amortization N/A N/A 5% annually N/A N/A Maturity date 12/30/2022 12/30/2022 12/31/2020 12/31/2020 12/31/2018 Fixed interest rate 2.204% 2.212% 1.108% 1.125% 0.896% The following table summarizes the contracts related to the Company’s foreign currency swaps, which settle in the base currency at various dates within 5 days after quarter-end: Aggregate Notional Amount March 31, (In thousands) 2018 2017 Australian dollar A$ 5,000 A$ 18,000
Location and Amounts of Derivative Gains and Losses in Condensed Consolidated Statements of Income	The following table presents information on the location and amounts of interest rate swap gains and losses: (In thousands) Three Months Ended March 31, Derivatives Not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income 1 2018 2017 Interest rate swap agreements – unrealized portion Net unrealized gains on interest rate swap agreements $ 13,508 $ 1,565 Interest rate swap agreements – realized portion Financing interest income (expense) $ 313 $ (543 ) 1 The Company has not elected hedge accounting treatment.

Financing and Other Debt (Table

Financing and Other Debt (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt	The following table summarizes the Company’s total outstanding debt: (In thousands) March 31, 2018 December 31, 2017 Revolving line-of-credit facility under 2016 Credit Agreement (a) $ 1,000 $ 136,535 Term loans under 2016 Credit Agreement (a) 1,746,799 1,602,875 Notes outstanding (a) 400,000 400,000 Securitized debt 145,587 126,901 Participation debt 166,361 184,990 WEX Latin America debt 9,377 9,747 Total gross debt $ 2,469,124 $ 2,461,048 Current portion of gross debt $ 308,638 $ 404,233 Less: unamortized debt issuance costs (7,928 ) (7,015 ) Short-term debt, net $ 300,710 $ 397,218 Long-term gross debt $ 2,160,486 $ 2,056,815 Less: unamortized debt issuance costs (28,203 ) $ (29,063 ) Long-term debt, net $ 2,132,283 $ 2,027,752 Supplemental information under 2016 Credit Agreement: Letters of credit (b) $ 52,600 $ 27,500 Borrowing capacity $ 516,400 $ 405,965 (a) See Note 11 , Fair Value, for more information regarding the Company’s 2016 Credit Agreement and notes outstanding. (b) Collateral for lease agreements, virtual card and fuel payment processing activity at the Company’s foreign subsidiaries

Deposits and Borrowed Federal35

Deposits and Borrowed Federal Funds (Tables)	3 Months Ended
	Mar. 31, 2018
Banking and Thrift [Abstract]
Schedule of Deposits	The following table presents the composition of deposits: (In thousands) March 31, 2018 December 31, 2017 Interest-bearing money market deposits $ 258,204 $ 285,899 Customer deposits 69,531 70,211 Certificates of deposit with maturities within 1 year (a) 451,123 630,879 Short-term deposits 778,858 986,989 Certificates of deposit with maturities greater than 1 year and less than 5 years (a) 330,043 306,865 Total deposits $ 1,108,901 $ 1,293,854 Weighted average cost of funds on certificates of deposit outstanding 1.79 % 1.51 % Weighted average cost of interest-bearing money market deposits 1.80 % 1.49 % (a) Certificates of deposit are classified as short-term or long-term within our unaudited condensed consolidated balance sheets based on maturity date.

Fair Value Fair Value (Tables)

Fair Value Fair Value (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value	The following table presents the Company’s assets and liabilities that are measured at fair value and the related hierarchy levels: (In thousands) Fair Value Hierarchy March 31, 2018 December 31, 2017 Assets Municipal bonds 2 $ 472 $ 534 Asset-backed securities 2 337 345 Mortgage-backed securities 2 300 305 Fixed-income mutual fund 1 21,940 22,174 Investment securities (a) $ 23,049 $ 23,358 Executive deferred compensation plan trust (b) 1 $ 7,565 $ 6,798 Interest rate swaps (c) 2 $ 32,059 $ 19,595 Liabilities Interest rate swaps (d) 2 $ 4,329 $ 5,373 (a) Not deemed available for current operations and have been classified as long-term assets. (b) The fair value of these instruments is recorded in other assets. (c) The fair value of these instruments is recorded in prepaid expenses and other current assets or other assets depending on the timing of expected discounted cash flows. (d) The fair value of these instruments is recorded in other current liabilities based on the timing of expected discounted cash flows.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Assumptions Used	The table below summarizes the assumptions used to calculate the fair value of service-based stock options by year of grant: 2018 2017 Weighted average expected life (in years) 6.0 6.0 Weighted average exercise price $ 158.23 $ 104.95 Weighted average volatility 27.35 % 30.67 % Weighted average risk-free rate 2.69 % 2.13 % Weighted average fair value $ 51.27 $ 35.58

Restructuring Activities (Table

Restructuring Activities (Tables)	3 Months Ended
	Mar. 31, 2018
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs	The following table presents the Company’s 2015 Restructuring Initiative liability: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of period $ 2,680 $ 5,231 Restructuring charges — 310 Reserve release (14 ) — Cash paid (409 ) (348 ) Impact of foreign currency translation 80 38 Balance, end of period $ 2,337 $ 5,231 The following table presents the Company’s 2016 Restructuring Initiative liability: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of period $ 738 $ 3,662 Reserve release (4 ) (533 ) Cash paid (315 ) — Impact of foreign currency translation 19 73 Balance, end of period $ 438 $ 3,202 The following table presents the Company’s Acquisition Integration Restructuring Initiative liability: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of period $ 5,093 $ 1,764 Restructuring charges 1 185 707 Cash paid (5,101 ) (590 ) Other 22 258 Impact of foreign currency translation 2 — Balance, end of period $ 201 $ 2,139 1 Primarily consists of office closure costs. The following table presents the Company’s total restructuring liability: Three Months Ended March 31, (In thousands) 2018 2017 Balance, beginning of period $ 8,511 $ 10,657 Restructuring charges 185 1,017 Reserve release (18 ) (533 ) Cash paid (5,825 ) (938 ) Other 22 258 Impact of foreign currency translation 101 111 Balance, end of period $ 2,976 $ 10,572

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Schedule of Revenue by Major Customers by Reporting Segments	The following tables present the Company’s reportable segment results: Three Months Ended March 31, 2018 (In thousands) Fleet Solutions Travel and Corporate Solutions Health and Employee Benefit Solutions Total Revenues Payment processing revenue $ 106,978 $ 44,777 $ 16,699 $ 168,454 Account servicing revenue 42,210 9,469 27,025 78,704 Finance fee revenue 43,604 259 5,819 49,682 Other revenue 37,573 12,274 8,142 57,989 Total revenues $ 230,365 $ 66,779 $ 57,685 $ 354,829 Interest income $ 995 $ 421 $ 6,768 $ 8,184
Schedule of Reportable Segment Results	Three Months Ended March 31, 2017 (In thousands) Fleet Solutions Travel and Corporate Solutions Health and Employee Benefit Solutions Total Revenues Payment processing revenue $ 86,262 $ 34,875 $ 15,241 $ 136,378 Account servicing revenue 36,069 155 25,315 61,539 Finance fee revenue 36,429 223 6,720 43,372 Other revenue 32,063 12,460 5,545 50,068 Total revenues $ 190,823 $ 47,713 $ 52,821 $ 291,357 Interest income $ 1,124 $ 46 $ 6,859 $ 8,029
Reconciliation of Adjusted Net Income to Income Before Income Taxes	The following table reconciles segment adjusted operating income to income before income taxes: Three Months Ended March 31, (In thousands) 2018 2017 Segment adjusted operating income Fleet Solutions $ 101,908 $ 83,983 Travel and Corporate Solutions 25,249 19,186 Health and Employee Benefit Solutions 18,639 18,199 Total segment adjusted operating income $ 145,796 $ 121,368 Reconciliation: Total segment adjusted operating income $ 145,796 $ 121,368 Less: Unallocated corporate expenses 13,920 12,298 Acquisition–related intangible amortization 35,236 37,978 Other acquisition and divestiture related items 637 2,136 Debt restructuring costs 3,015 — Stock–based compensation 8,955 6,457 Restructuring and other costs 5,671 1,747 Operating income 78,362 60,752 Financing interest expense (27,337 ) (27,148 ) Net foreign currency gain 390 8,442 Net unrealized gains on interest rate swap agreements 13,508 1,565 Income before income taxes $ 64,923 $ 43,611

Supplementary Regulatory Capi40

Supplementary Regulatory Capital Disclosure (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	WEX Bank’s actual and regulatory minimum capital amounts and ratios are presented in the following table: (In thousands) Actual Amount Ratio Minimum for Capital Adequacy Purposes Amount Ratio Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount Ratio March 31, 2018 Total Capital to risk-weighted assets $ 311,040 12.80 % $ 194,418 8.0 % $ 243,023 10.0 % Tier 1 Capital to average assets $ 298,226 11.32 % $ 105,341 4.0 % $ 131,676 5.0 % Common equity to risk-weighted assets $ 298,226 12.27 % $ 109,360 4.5 % $ 157,965 6.5 % Tier 1 Capital to risk-weighted assets $ 298,226 12.27 % $ 145,814 6.0 % $ 194,418 8.0 % December 31, 2017 Total Capital to risk-weighted assets $ 316,129 13.38 % $ 188,991 8.0 % $ 236,239 10.0 % Tier 1 Capital to average assets $ 304,555 12.50 % $ 97,452 4.0 % $ 121,815 5.0 % Common equity to risk-weighted assets $ 304,555 12.89 % $ 106,308 4.5 % $ 153,555 6.5 % Tier 1 Capital to risk-weighted assets $ 304,555 12.89 % $ 141,743 6.0 % $ 188,991 8.0 %

Basis of Presentation Basis of

Basis of Presentation Basis of Presentation (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Assets	$ 6,755,620		$ 6,742,851
Liabilities	$ 4,985,431		$ 5,022,293
Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Assets		$ 3,700
Liabilities		$ 3,700

Recent Accounting Pronounceme42

Recent Accounting Pronouncements (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)segment	Mar. 31, 2017USD ($)	Jan. 01, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 354,829	$ 291,357
Number of operating segments | segment	3,000
Fleet Solutions And Travel And Corporate Solutions | Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 14,900
Operating expenses	14,900
Travel and corporate solutions
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	66,779	47,713
Travel and corporate solutions | Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	(5,600)
Operating expenses	(5,600)
Health and Employee Benefit Solutions
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenues	$ 57,685	$ 52,821
Health and Employee Benefit Solutions | Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment			$ 600

Revenue - Summary of Disaggrega

Revenue - Summary of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	$ 239,715
Revenues	354,829	$ 291,357
Fleet Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	132,486
Revenues	230,365	190,823
Travel and corporate solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	55,363
Revenues	66,779	47,713
Health and Employee Benefit Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	51,866
Revenues	57,685	$ 52,821
Payment processing revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	168,454
Payment processing revenue | Fleet Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	106,978
Payment processing revenue | Travel and corporate solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	44,777
Payment processing revenue | Health and Employee Benefit Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	16,699
Account servicing revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	44,960
Revenues	33,744
Account servicing revenue | Fleet Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	8,466
Revenues	33,744
Account servicing revenue | Travel and corporate solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	9,469
Revenues	0
Account servicing revenue | Health and Employee Benefit Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	27,025
Revenues	0
Finance fee revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	49,682
Finance fee revenue | Fleet Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	43,604
Finance fee revenue | Travel and corporate solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	259
Finance fee revenue | Health and Employee Benefit Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	5,819
Other revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	26,301
Revenues	31,688
Other revenue | Fleet Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	17,042
Revenues	20,531
Other revenue | Travel and corporate solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	1,117
Revenues	11,157
Other revenue | Health and Employee Benefit Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue from contract with customer	8,142
Revenues	0
Topic 310 Revenues
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	115,114
Topic 310 Revenues | Fleet Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	97,879
Topic 310 Revenues | Travel and corporate solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	11,416
Topic 310 Revenues | Health and Employee Benefit Solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ 5,819

Revenue - Contract Assets and L

Revenue - Contract Assets and Liabilities From Contracts with Customers (Details)	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Variable consideration	$ 198,500,000
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract assets	53,363
Contract liabilities	23,841
Accounts receivable
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract assets	$ 19,379

Revenue - Remaining Performance

Revenue - Remaining Performance Obligation (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 47,272
Performance obligations expected to be satisfied, expected timing	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01 | Monthly Fees
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 34,432
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01 | Professional Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	12,840
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 33,177
Performance obligations expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 | Monthly Fees
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 30,814
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 | Professional Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	2,363
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 17,565
Performance obligations expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01 | Monthly Fees
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 17,565
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01 | Professional Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 9,719
Performance obligations expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Monthly Fees
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 9,719
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Professional Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 5,744
Performance obligations expected to be satisfied, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Monthly Fees
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 5,744
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Professional Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	267
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Monthly Fees
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	267
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Professional Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 113,744
Performance obligations expected to be satisfied, expected timing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | Monthly Fees
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 98,541
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | Professional Services
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied	$ 15,203

Business Acquisition (Details)

Business Acquisition (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Oct. 18, 2017
Less:
Recorded goodwill	$ 1,876,922	$ 1,876,132
AOC
Business Acquisition [Line Items]
Total consideration	129,828	129,828	$ 129,800
Less:
Cash	15,546	15,546
Accounts receivable	4,171	4,171
Property and equipment	1,201	2,530
Other liabilities	(1,134)	(685)
Recorded goodwill	69,274	67,706
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Total consideration	0
Cash	0
Accounts receivable	0
Property and equipment	(1,329)
Other liabilities	(449)
Recorded goodwill	$ 1,568
Weighted average life (in years)	5 years 6 months
Total revenues		6,700
Net loss before taxes		600
Customer relationships | AOC
Less:
Intangible assets	$ 15,200	15,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Intangible assets	$ 200
Weighted average life (in years)	9 years
Developed technologies | AOC
Less:
Intangible assets	$ 24,100	24,100
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Intangible assets	$ 0
Weighted average life (in years)	3 years 4 months 24 days
Trademarks and trade names | AOC
Less:
Intangible assets	$ 1,470	$ 1,460
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments [Abstract]
Intangible assets	$ 10
Weighted average life (in years)	4 years 3 months 18 days

Accounts Receivable - Additiona

Accounts Receivable - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Trade receivable payments terms (30 days or less)	30 days
Threshold period past due for write-off of trade accounts receivable	150 days
Revolving line-of-credit facility under 2016 Credit Agreement
Concentration Risk [Line Items]
Receivables with revolving credit balances	$ 14.1	$ 12.2
29 days or less past due | Credit Concentration Risk | Accounts receivable
Concentration Risk [Line Items]
Concentration risk, percentage	96.00%	95.00%
59 days or less past due | Credit Concentration Risk | Accounts receivable
Concentration Risk [Line Items]
Concentration risk, percentage	98.00%	97.00%

Accounts Receivable - Changes i

Accounts Receivable - Changes in Reserves for Accounts Receivable (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of year	$ 30,207	$ 20,092
Provision for credit losses	13,990	12,231
Charges to other accounts	4,442	2,939
Charge-offs	(19,221)	(13,369)
Recoveries of amounts previously charged-off	1,926	928
Currency translation	99	745
Balance, end of period	$ 31,443	$ 23,566

Earnings per Share - Summary of

Earnings per Share - Summary of Net Earning Attributable to Shareholders and Reconciliation of Basic and Diluted Shares (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income attributable to shareholders	$ 48,633	$ 29,401
Weighted average common shares outstanding – Basic (in shares)	43,049	42,871
Dilutive impact of share-based compensation awards (in shares)	401	248
Weighted average common shares outstanding – Diluted (in shares)	43,450	43,119

Earnings per Share - Stock Opti

Earnings per Share - Stock Options and Restricted Stock Units (Details) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	0

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Details)	3 Months Ended
	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2017contract
Derivative [Line Items]
Lines of credit outstanding	$ 1,700,000,000
Interest rate swaps
Derivative [Line Items]
Number of derivative instruments held (agreement) | contract			5
Borrowings under derivative agreements	$ 1,300,000,000
Interest rate swaps | Minimum
Derivative [Line Items]
Fixed rate variable interest	0.896%
Interest rate swaps | Maximum
Derivative [Line Items]
Fixed rate variable interest	2.212%
Currency Swap
Derivative [Line Items]
Derivative term	5 days
Gain (loss) on foreign currency derivatives	$ 0	$ 0

Financing and Other Debt - Sche

Financing and Other Debt - Schedule of Debt (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,469,124,000	$ 2,461,048,000
Current portion of gross debt	308,638,000	404,233,000
Less: unamortized debt issuance costs	(7,928,000)	(7,015,000)
Short-term debt, net	300,710,000	397,218,000
Long-term gross debt	2,160,486,000	2,056,815,000
Less: unamortized debt issuance costs	(28,203,000)	(29,063,000)
Long-term debt, net	2,132,283,000	2,027,752,000
Lines of credit outstanding	1,700,000,000
Maximum borrowing capacity	275,000,000
Loan Participations and Assignments
Debt Instrument [Line Items]
Long-term debt, gross	166,361,000	184,990,000
WEX Latin America Securitization Facility
Debt Instrument [Line Items]
Long-term debt, gross	9,377,000	9,747,000
Secured debt
Debt Instrument [Line Items]
Long-term debt, gross	145,587,000	126,901,000
Line of Credit
Debt Instrument [Line Items]
Lines of credit outstanding	0	0
Line of Credit | Revolving line-of-credit facility under 2016 Credit Agreement | 2016 Credit Agreement
Debt Instrument [Line Items]
Long-term debt, gross	1,000,000	136,535,000
Line of Credit | Secured debt | 2016 Credit Agreement
Debt Instrument [Line Items]
Long-term debt, gross	1,746,799,000	1,602,875,000
Notes payable
Debt Instrument [Line Items]
Long-term debt, gross	400,000,000	400,000,000
Revolving line-of-credit facility under 2016 Credit Agreement | 2016 Credit Agreement
Debt Instrument [Line Items]
Maximum borrowing capacity	516,400,000	405,965,000
Letter of Credit | Revolving line-of-credit facility under 2016 Credit Agreement | 2016 Credit Agreement
Debt Instrument [Line Items]
Lines of credit outstanding	$ 52,600,000	$ 27,500,000

Derivative Instruments - Schedu

Derivative Instruments - Schedule of Interest Rate Swaps (Details) - Derivatives Not Designated as Hedging Instruments	Mar. 31, 2018USD ($)
Tranche A
Derivative [Line Items]
Notional amount at inception (in thousands)	$ 300,000,000
Fixed interest rate	2.204%
Tranche B
Derivative [Line Items]
Notional amount at inception (in thousands)	$ 200,000,000
Fixed interest rate	2.212%
Tranche C
Derivative [Line Items]
Notional amount at inception (in thousands)	$ 400,000,000
Amortization	5.00%
Fixed interest rate	1.108%
Tranche D
Derivative [Line Items]
Notional amount at inception (in thousands)	$ 150,000,000
Fixed interest rate	1.125%
Tranche E
Derivative [Line Items]
Notional amount at inception (in thousands)	$ 250,000,000
Fixed interest rate	0.896%

Financing and Other Debt - Addi

Financing and Other Debt - Additional Information (Details) - USD ($)	Jan. 17, 2018	Apr. 07, 2016	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Jan. 16, 2018	Jul. 01, 2016
Debt Instrument [Line Items]
Loss on extinguishment of debt	$ 1,100,000
General and administrative costs incurred	3,000,000
Debt issuance costs	$ 2,900,000
Payments for equity method investments			$ 2,307,000	$ 0
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Interest rate during period, percent	2.30%
Base Rate
Debt Instrument [Line Items]
Interest rate during period, percent	1.25%
Interest Rate Option Two | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			1.00%
Interest Rate Option Two | Federal Fund Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			0.50%
2016 Credit Agreement Tranche A | Interest Rate Option One | Eurocurrency Rate
Debt Instrument [Line Items]
Basis spread on variable rate, reduction in basis points							0.50%
Margin on variable rate, percent			2.00%
2016 Credit Agreement Tranche A | Interest Rate Option One | Minimum | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			1.75%
2016 Credit Agreement Tranche A | Interest Rate Option One | Maximum | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			2.75%
2016 Credit Agreement Tranche A | Interest Rate Option Two | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			1.00%
2016 Credit Agreement Tranche A | Interest Rate Option Two | Minimum | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			0.75%
2016 Credit Agreement Tranche A | Interest Rate Option Two | Maximum | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			1.75%
2016 Credit Agreement Tranche B
Debt Instrument [Line Items]
Weighted average annual interest rate, percent			4.10%		4.20%
2016 Credit Agreement Tranche B | Interest Rate Option One | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			2.25%
Debt instrument, interest rate, floor			0.00%
2016 Credit Agreement Tranche B | Interest Rate Option Two | Minimum | Eurocurrency Rate
Debt Instrument [Line Items]
Interest rate, stated percentage			1.75%
2016 Credit Agreement | Interest Rate Option One | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			2.25%
2016 Credit Agreement | Interest Rate Option One | Minimum | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			1.75%
2016 Credit Agreement | Interest Rate Option One | Maximum | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			3.25%
2016 Credit Agreement | Interest Rate Option Two | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			1.25%
2016 Credit Agreement | Interest Rate Option Two | Minimum | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			0.75%
2016 Credit Agreement | Interest Rate Option Two | Maximum | Eurocurrency Rate
Debt Instrument [Line Items]
Margin on variable rate, percent			2.25%
Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage			4.75%		4.75%
Australian Securitization Facility
Debt Instrument [Line Items]
Interest rate during period, percent			2.68%		2.53%
Debt instrument, term			1 year
Percentage used as collateral			85.00%
Short-term debt, net			$ 90,400,000		$ 90,000,000
WEX Latin America Securitization Facility
Debt Instrument [Line Items]
Payments for equity method investments			$ 2,300,000
European Securitization Facility
Debt Instrument [Line Items]
Interest rate during period, percent			0.30%		1.11%
Debt instrument, term		5 years
Securitized debt			$ 23,500,000		$ 17,900,000
Loan Participations and Assignments
Debt Instrument [Line Items]
Debt balance			$ 166,400,000		$ 185,000,000
Loan Participations and Assignments | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Margin on variable rate, percent			2.25%
Loan Participations and Assignments, Amounts Maturing May 2018
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount			$ 85,000,000
Loan Participations and Assignments, Amounts Maturing December 2021
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount			50,000,000
Loan Participations and Assignments, Amounts Maturing On Demand
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount			31,400,000
Credit Facility Term Loans | 2016 Credit Agreement Tranche A
Debt Instrument [Line Items]
Current borrowing capacity			455,000,000
Mandatory quarterly payments			5,700,000
Credit Facility Term Loans | 2016 Credit Agreement Tranche B
Debt Instrument [Line Items]
Current borrowing capacity	$ 1,335,000,000		1,335,000,000			$ 1,182,000,000
Mandatory quarterly payments			3,400,000
Revolving line-of-credit facility under 2016 Credit Agreement | 2016 Credit Agreement
Debt Instrument [Line Items]
Current borrowing capacity			$ 570,000,000
WEX Latin America
Debt Instrument [Line Items]
Weighted average annual interest rate, percent			16.20%		21.20%
Outstanding debt			$ 9,400,000		$ 9,700,000
WEX Latin America | WEX Latin America Securitization Facility
Debt Instrument [Line Items]
Securitized debt			31,600,000		19,000,000
Servicing fee income			2,100,000
Reported Value Measurement | Senior Notes
Debt Instrument [Line Items]
Senior notes			$ 400,000,000		$ 400,000,000

Derivative Instruments - Locati

Derivative Instruments - Location and Amounts of Interest Rate Swap Gains and Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Net unrealized gains on interest rate swap agreements	$ 13,508	$ 1,565
Derivatives Not Designated as Hedging Instruments | Net unrealized gain on interest rate swap agreements | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net unrealized gains on interest rate swap agreements	13,508	1,565
Derivatives Not Designated as Hedging Instruments | Financing interest income | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net unrealized gains on interest rate swap agreements	$ 313	$ (543)

Derivative Instruments - Sche56

Derivative Instruments - Schedule of Foreign Currency Swaps (Details) - AUD ($)	Mar. 31, 2018	Mar. 31, 2017
Derivatives Not Designated as Hedging Instruments | Currency Swap
Derivative [Line Items]
Australian dollar	$ 5,000,000	$ 18,000,000

Deposits and Borrowed Federal57

Deposits and Borrowed Federal Funds - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Apr. 01, 2018
Debt Instrument [Line Items]
Certificates of deposits denominations in dollar amount	$ 250,000
Maximum money market and demand deposit accounts purchasable	125,000,000
Lines of credit outstanding	1,700,000,000
Maximum borrowing capacity	$ 275,000,000
Minimum
Debt Instrument [Line Items]
Certificate of deposits maturities period	6 months
Certificate of deposits, fixed interest rates range (as a percent)	1.15%	1.00%
Maximum
Debt Instrument [Line Items]
Certificate of deposits maturities period	3 years
Certificate of deposits, fixed interest rates range (as a percent)	2.55%	2.15%
Line of Credit
Debt Instrument [Line Items]
Lines of credit outstanding	$ 0	$ 0
Subsequent Event
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 150,000,000

Deposits and Borrowed Federal58

Deposits and Borrowed Federal Funds - Schedule of Composition of Deposits (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Banking and Thrift [Abstract]
Interest-bearing money market deposits	$ 258,204	$ 285,899
Customer deposits	69,531	70,211
Certificates of deposit with maturities within 1 year	451,123	630,879
Short-term deposits	778,858	986,989
Certificates of deposit with maturities greater than 1 year and less than 5 years	330,043	306,865
Total deposits	$ 1,108,901	$ 1,293,854
Weighted average cost of funds on certificates of deposit outstanding (as a percent)	1.79%	1.51%
Weighted average cost of interest-bearing money market deposits (as a percent)	1.80%	1.49%

Off-Balance Sheet Arrangements

Off-Balance Sheet Arrangements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Receivables [Abstract]
Proceeds from sale of factoring receivables	$ 170.2
Loss on sale of factoring receivables	1.1	$ 0
Amount of factoring receivables	30.3
Amount of factoring receivables, portion in excess of the established credit limit	$ 0.5

Fair Value - Assets and Liabili

Fair Value - Assets and Liabilities Measured at Fair Value and Related Hierarchy Levels (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets
Total available-for-sale securities	$ 23,049	$ 23,358
Level 2 | Interest rate swaps
Assets
Derivative asset		19,595
Liabilities
Interest rate swaps		5,373
Level 1
Assets
Executive deferred compensation plan trust	7,565	6,798
Municipal bonds | Level 2
Assets
Total available-for-sale securities	472	534
Asset-backed securities | Level 2
Assets
Total available-for-sale securities	337	345
Mortgage-backed securities | Level 2
Assets
Total available-for-sale securities	300	305
Fixed-income mutual fund | Level 1
Assets
Total available-for-sale securities	21,940	$ 22,174
Derivatives Not Designated as Hedging Instruments | Other Assets | Interest rate swaps
Assets
Derivative Asset, Fair Value, Gross Asset	32,059
Derivatives Not Designated as Hedging Instruments | Other Liabilities | Level 2 | Interest rate swaps
Liabilities
Interest rate swaps	$ 4,329

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Senior Notes | Estimate of Fair Value Measurement | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 402	$ 410

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Effective tax rate	24.00%		33.30%
Tax Act, provisional income tax benefit		$ 60,600
Undistributed earnings of certain foreign subsidiaries	$ 73,400	$ 58,675

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Fair value of units awarded	$ 27.4	$ 28.1

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Assumptions Used to Calculate Fair Value of Stock Options (Details) - Stock Options - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected life (in years)	6 years	6 years
Weighted average exercise price (in dollars per share)	$ 158.23	$ 104.95
Weighted average volatility	27.35%	30.67%
Weighted average risk–free rate	2.69%	2.13%
Weighted average fair value (in dollars per share)	$ 51.27	$ 35.58

Restructuring Activities - Addi

Restructuring Activities - Additional Information (Details) $ in Millions	Mar. 31, 2018USD ($)
Restructuring and Related Activities [Abstract]
Restructuring charges incurred to date	$ 24.7

Restructuring Activities - Sche

Restructuring Activities - Schedule of Restructuring Reserve (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Restructuring Reserve
Balance, beginning of period	$ 8,511	$ 10,657
Restructuring charges	185	1,017
Reserve release	(18)	(533)
Cash paid	(5,825)	(938)
Other	22	258
Impact of foreign currency translation	101	111
Balance, end of period	2,976	10,572
Year 2,015
Restructuring Reserve
Balance, beginning of period	2,680	5,231
Restructuring charges	0	310
Reserve release	(14)	0
Cash paid	(409)	(348)
Impact of foreign currency translation	80	38
Balance, end of period	2,337	5,231
Year 2,016
Restructuring Reserve
Balance, beginning of period	738	3,662
Reserve release	(4)	(533)
Cash paid	(315)	0
Impact of foreign currency translation	19	73
Balance, end of period	438	3,202
Acquisition Integration Restructuring Initiative
Restructuring Reserve
Balance, beginning of period	5,093	1,764
Restructuring charges	185	707
Cash paid	(5,101)	(590)
Other	22	258
Impact of foreign currency translation	2	0
Balance, end of period	$ 201	$ 2,139

Segment Information - Additiona

Segment Information - Additional Information (Details)	3 Months Ended
	Mar. 31, 2018segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information - Revenue b

Segment Information - Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Payment processing revenue	$ 168,454	$ 136,378
Account servicing revenue	78,704	61,539
Finance fee revenue	49,682	43,372
Other revenue	57,989	50,068
Total revenues	354,829	291,357
Interest income	8,184	8,029
Fleet Solutions
Segment Reporting Information [Line Items]
Payment processing revenue	106,978	86,262
Account servicing revenue	42,210	36,069
Finance fee revenue	43,604	36,429
Other revenue	37,573	32,063
Total revenues	230,365	190,823
Interest income	995	1,124
Travel and Corporate Solutions
Segment Reporting Information [Line Items]
Payment processing revenue	44,777	34,875
Account servicing revenue	9,469	155
Finance fee revenue	259	223
Other revenue	12,274	12,460
Total revenues	66,779	47,713
Interest income	421	46
Health and Employee Benefit Solutions
Segment Reporting Information [Line Items]
Payment processing revenue	16,699	15,241
Account servicing revenue	27,025	25,315
Finance fee revenue	5,819	6,720
Other revenue	8,142	5,545
Total revenues	57,685	52,821
Interest income	$ 6,768	$ 6,859

Segment Information - Reconcili

Segment Information - Reconciliation of Adjusted Operating Income to Income Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Adjusted operating income	$ 145,796	$ 121,368
Stock-based compensation	8,955	6,457
Restructuring and other costs	185	1,017
Operating income	78,362	60,752
Financing interest expense	(27,337)	(27,148)
Net foreign currency gain	390	8,442
Net unrealized gains on interest rate swap agreements	13,508	1,565
Income before income taxes	64,923	43,611
Fleet Solutions
Segment Reporting Information [Line Items]
Adjusted operating income	101,908	83,983
Travel and corporate solutions
Segment Reporting Information [Line Items]
Adjusted operating income	25,249	19,186
Health and Employee Benefit Solutions
Segment Reporting Information [Line Items]
Adjusted operating income	18,639	18,199
Segment reconciling items
Segment Reporting Information [Line Items]
Unallocated corporate expenses	13,920	12,298
Acquisition–related intangible amortization	35,236	37,978
Other acquisition and divestiture related items	637	2,136
Debt restructuring costs	3,015	0
Stock-based compensation	8,955	6,457
Restructuring and other costs	$ 5,671	$ 1,747

Supplementary Regulatory Capi70

Supplementary Regulatory Capital Disclosure (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Total Capital to risk-weighted assets, Actual Amount	$ 311,040	$ 316,129
Total Capital to risk-weighted assets, Actual, Ratio	12.80%	13.38%
Total Capital to risk-weighted assets, Minimum for Capital Adequacy Purposes Amount	$ 194,418	$ 188,991
Total Capital to risk-weighted assets, Minimum for Capital Adequacy Purposes, Ratio	8.00%	8.00%
Total Capital to risk-weighted assets, Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 243,023	$ 236,239
Total Capital to risk-weighted assets, Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%	10.00%
Tier 1 Capital to average assets, Actual Amount	$ 298,226	$ 304,555
Tier 1 Capital to average assets, Actual, Ratio	11.32%	12.50%
Tier 1 Capital to average assets, Minimum for Capital Adequacy Purposes Amount	$ 105,341	$ 97,452
Tier 1 Capital to average assets, Minimum for Capital Adequacy Purposes, Ratio	4.00%	4.00%
Tier 1 Capital to average assets, Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 131,676	$ 121,815
Tier 1 Capital to average assets, Minimum to Be Well Capitalized Under Prompt Corrective Action Provision, Ratio	5.00%	5.00%
Common equity to risk-weighted assets, Actual Amount	$ 298,226	$ 304,555
Common equity to risk-weighted assets, Actual, Ratio	12.27%	12.89%
Common equity to risk-weighted assets, Minimum for Capital Adequacy Purposes Amount	$ 109,360	$ 106,308
Common equity to risk-weighted assets, Minimum for Capital Adequacy Purposes, Ratio	4.50%	4.50%
Common equity to risk-weighted assets, Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 157,965	$ 153,555
Common equity to risk-weighted assets, Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%	6.50%
Tier 1 Capital to risk-weighted assets, Actual Amount	$ 298,226	$ 304,555
Tier 1 Capital to risk-weighted assets, Actual, Ratio	12.27%	12.89%
Tier 1 Capital to risk-weighted assets, Minimum for Capital Adequacy Purposes Amount	$ 145,814	$ 141,743
Tier 1 Capital to risk-weighted assets, Minimum for Capital Adequacy Purposes, Ratio	6.00%	6.00%
Tier 1 Capital to risk-weighted assets, Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 194,418	$ 188,991
Tier 1 capital to risk-weighted assets, Minimum to Be Well Capitalized Under Prompt Corrective Action Provisions Amount, Ratio	8.00%	8.00%