Business Combinations (Narrative) (Details) $ in Thousands										3 Months Ended		12 Months Ended
		Feb. 01, 2018 USD ($)	Nov. 01, 2017 USD ($)	Oct. 01, 2017 USD ($)	Sep. 01, 2017 USD ($)	Jun. 01, 2017 USD ($)	Apr. 01, 2017 USD ($)	Jul. 02, 2016 USD ($)	Sep. 02, 2015 USD ($)	Mar. 31, 2018 USD ($) Companies	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) Companies	Dec. 31, 2016 USD ($)	Jul. 01, 2016	Sep. 01, 2015
Business Acquisition [Line Items]
Recognized controlling ownership of joint venture										$ (389)
Non-operating income, gain on joint venture investment (see Note 8)										$ 53	$ 0	$ 1,162
Number of Businesses Acquired | Companies										1		6
Reduction of acquisition earnout accruals											0
Goodwill, Translation and Purchase Accounting Adjustments	[1]									$ 0	0	$ (4,007)
Derivative Liability										36,511		37,096	$ 8,510
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability										0	$ 0
Goodwill, Purchase Accounting Adjustments										1,528		(12,158)
Goodwill										672,159		666,863	$ 441,404
Fair Value of Joint Venture, excluding Noncontrolling Interest							$ 120,000
Fair Value of Joint Venture, including Noncontrolling Interest							150,000
Transcorp [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		$ 7,300
Payments to Acquire Businesses, Net		6,550
Business Combination, Consideration Transferred, Liabilities Incurred		$ 700
Via [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross			$ 78,800
Derivative, Term of Contract			12 months
PML [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross			$ 37,400
Wallstreet [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross				$ 7,400
YouFirst [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross					$ 10,200
beBetter [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross						$ 1,000
Derivative, Term of Contract						24 months
ItzCash [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross							$ 76,300
Derivative Liability										33,960
Derivative, Term of Contract							36 months
Payments to Acquire Business, Held in Escrow							$ 4,000
Escrow Derivative, Term of Contract							12 months
Maximum [Member] | beBetter [Member]
Business Acquisition [Line Items]
Derivative Liability						$ 2,000
Maximum [Member] | ItzCash [Member]
Business Acquisition [Line Items]
Derivative Liability							$ 44,000
Potential claims made by tax authorities [Member] | Via [Member]
Business Acquisition [Line Items]
Derivative Liability			2,300
Refund of Advance and withholding taxes [Member] | Via [Member]
Business Acquisition [Line Items]
Derivative Liability			$ 2,000
Contingent accrued earn-out acquisition consideration [Member]
Business Acquisition [Line Items]
Derivative Liability										36,511		37,096
Contingent liability for accrued earn-out acquisition consideration										32,500		33,100
Business acquisition, contingent consideration, at fair value, current										$ 4,000		$ 4,000
ItzCash [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage							80.00%
EbixHealth JV [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage Increase (Decrease)								11.00%
Payments to Acquire Interest in Joint Venture								$ 2,000	$ 6,000
Equity Method Investment, Ownership Percentage														51.00%	40.00%

[1] Recorded as an adjustment to reported general and administrative expenses