Business Acquisitions - Narrative (Details) - USD ($) $ in Thousands										1 Months Ended	3 Months Ended		12 Months Ended
	Aug. 23, 2019	Jan. 01, 2019	Dec. 01, 2018	Oct. 01, 2018	Aug. 01, 2018	Jul. 01, 2018	Apr. 01, 2018	Feb. 01, 2018	Apr. 01, 2017	Dec. 31, 2018	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Jul. 01, 2016
Business Acquisition [Line Items]
Reduction of acquisition earn-out contingent liability													$ (16,543)	$ (1,391)	$ (164)
Derivative liability										$ 24,976		$ 24,976	10,095	24,976	37,096
Contingent liability for accrued earn-out acquisition consideration										11,209		11,209	1,474	11,209
Contingent liability for accrued earn-out acquisition consideration										13,767		13,767	8,621	13,767
Payments to acquire businesses, net of cash acquired													105,466	232,557	192,161
Business acquisition, purchase price allocation, goodwill										946,685		946,685	952,404	946,685	666,863
Goodwill, purchase accounting adjustments													(741)	11,080
Goodwill										946,685		946,685	952,404	946,685	$ 666,863
Final Allocation
Business Acquisition [Line Items]
Derivative liability										8,581		8,581	1,922	8,581
Business acquisition, purchase price allocation, goodwill										322,624		322,624	17,932	322,624
Goodwill										322,624		322,624	17,932	$ 322,624
Wallstreet Canada
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid	$ 2,100
Wallstreet Canada | Final Allocation
Business Acquisition [Line Items]
Derivative liability	0
Business acquisition, purchase price allocation, goodwill	71
Goodwill	$ 71
Weizmann
Business Acquisition [Line Items]
Cash acquired from acquisition increase (decrease)													1,500
Business acquisition, cost of acquired entity, cash paid			$ 63,100							$ 21,100			12,700
Payments to acquire businesses, net of cash acquired													$ 77,350
Ownership percentage increase (decrease)													15.10%
Weizmann | Final Allocation
Business Acquisition [Line Items]
Derivative liability			0
Business acquisition, purchase price allocation, goodwill			71,552
Goodwill			71,552
Pearl
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid			3,400
Pearl | Final Allocation
Business Acquisition [Line Items]
Derivative liability			0
Business acquisition, purchase price allocation, goodwill			3,372
Goodwill			3,372
Lawson
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid			2,700
Lawson | Final Allocation
Business Acquisition [Line Items]
Derivative liability			0
Business acquisition, purchase price allocation, goodwill			4,437
Goodwill			$ 4,437
AHA Taxis
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid				$ 382							$ 214	71	$ 72
AHA Taxis | Final Allocation
Business Acquisition [Line Items]
Derivative liability				0
Business acquisition, purchase price allocation, goodwill				592
Goodwill				592
Routier
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid				413
Routier | Final Allocation
Business Acquisition [Line Items]
Derivative liability				0
Business acquisition, purchase price allocation, goodwill				698
Goodwill				698
Business Travels
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid				$ 1,100							$ 689	$ 414
Miles
Business Acquisition [Line Items]
Derivative liability													7,700
Derivative, term of contract					24 months
Business acquisition, cost of acquired entity, cash paid					$ 18,300
Miles | Final Allocation
Business Acquisition [Line Items]
Derivative liability					5,271
Business acquisition, purchase price allocation, goodwill					19,075
Goodwill					19,075
ItzCash
Business Acquisition [Line Items]
Derivative, term of contract									36 months
Escrow derivative, term of contract									12 months
Leisure
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid						$ 1,600
Leisure | Final Allocation
Business Acquisition [Line Items]
Derivative liability						0
Business acquisition, purchase price allocation, goodwill						1,699
Goodwill						1,699
Mercury
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid						13,200
Mercury | Final Allocation
Business Acquisition [Line Items]
Derivative liability						0
Business acquisition, purchase price allocation, goodwill						15,127
Goodwill						$ 15,127
Indus
Business Acquisition [Line Items]
Derivative liability													0
Derivative, term of contract						24 months
Business acquisition, cost of acquired entity, cash paid						$ 22,900
Indus | Final Allocation
Business Acquisition [Line Items]
Derivative liability						3,310
Business acquisition, purchase price allocation, goodwill						21,501
Goodwill						21,501
CDL (Centrum)
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid							$ 179,500
CDL (Centrum) | Final Allocation
Business Acquisition [Line Items]
Derivative liability							0
Business acquisition, purchase price allocation, goodwill							159,647
Goodwill							159,647
Transcorp
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity, cash paid								$ 7,250
Payments to acquire businesses, net								6,550
Business combination, consideration transferred, liabilities incurred								700
Transcorp | Final Allocation
Business Acquisition [Line Items]
Derivative liability								0
Business acquisition, purchase price allocation, goodwill								7,254
Goodwill								$ 7,254
Essel
Business Acquisition [Line Items]
Derivative liability													$ 396
Business acquisition, cost of acquired entity, cash paid		$ 8,700
Essel | Final Allocation
Business Acquisition [Line Items]
Derivative liability		407
Business acquisition, purchase price allocation, goodwill		8,372
Goodwill		8,372
Zillious
Business Acquisition [Line Items]
Derivative liability																$ 1,500
Business acquisition, cost of acquired entity, cash paid		10,100
Zillious | Final Allocation
Business Acquisition [Line Items]
Derivative liability		1,515
Business acquisition, purchase price allocation, goodwill		9,489
Goodwill		9,489
Maximum | Miles
Business Acquisition [Line Items]
Derivative liability					$ 8,300
Maximum | Indus
Business Acquisition [Line Items]
Derivative liability						$ 5,000
Maximum | Essel
Business Acquisition [Line Items]
Derivative liability		721
Maximum | Zillious
Business Acquisition [Line Items]
Derivative liability		$ 2,200
Zillious
Business Acquisition [Line Items]
Ownership percentage		80.00%
Weizmann
Business Acquisition [Line Items]
Ownership percentage			74.84%							25.16%		25.16%	89.94%	25.16%
AHA Taxis
Business Acquisition [Line Items]
Ownership percentage				70.00%
Routier
Business Acquisition [Line Items]
Ownership percentage				67.00%
Smartclass
Business Acquisition [Line Items]
Payments to acquire interest in joint venture							$ 8,600
Ownership percentage							60.00%
EbixHealth JV; final purchase allocation adjustments
Business Acquisition [Line Items]
Ownership percentage																	51.00%
Contingent Accrued Earn-out Acquisition Consideration
Business Acquisition [Line Items]
Derivative liability										$ 25,000		$ 25,000	$ 10,100	$ 25,000