Changes in Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill	$ 1,924,052	$ 1,222,601
Additions arising from business acquisitions	79,910	703,074
Other additions	4,970	65,334
Reallocation		0
Foreign exchange translation	991	(1,623)
Goodwill, net	2,004,953	1,924,052
Netsmart Acquisition [Member]
Goodwill [Line Items]
Additions arising from business acquisitions		619,283
HealthMEDX, LLC [Member]
Goodwill [Line Items]
Additions arising from business acquisitions		18,457
DeVero Acquisition [Member]
Goodwill [Line Items]
Additions arising from business acquisitions	32,363
NantHealth, Inc. [Member]
Goodwill [Line Items]
Additions arising from business acquisitions	13,350
Enterprise Information Solutions [Member]
Goodwill [Line Items]
Increase in the residual allocation to goodwill	29,227
Clinical and Financial Solutions [Member]
Goodwill [Line Items]
Goodwill	843,837	796,367
Additions arising from business acquisitions	16,787	49,093
Other additions	420	49,093
Reallocation		0
Foreign exchange translation	991	(1,623)
Goodwill, net	861,615	843,837
Clinical and Financial Solutions [Member] | Netsmart Acquisition [Member]
Goodwill [Line Items]
Additions arising from business acquisitions		0
Clinical and Financial Solutions [Member] | HealthMEDX, LLC [Member]
Goodwill [Line Items]
Additions arising from business acquisitions		0
Clinical and Financial Solutions [Member] | DeVero Acquisition [Member]
Goodwill [Line Items]
Additions arising from business acquisitions	0
Clinical and Financial Solutions [Member] | NantHealth, Inc. [Member]
Goodwill [Line Items]
Additions arising from business acquisitions	0
Clinical and Financial Solutions [Member] | Enterprise Information Solutions [Member]
Goodwill [Line Items]
Increase in the residual allocation to goodwill	16,367
Population Health [Member]
Goodwill [Line Items]
Goodwill	404,875	426,234
Additions arising from business acquisitions	26,257	16,241
Other additions	47	16,241
Reallocation		(37,600)
Foreign exchange translation	0	0
Goodwill, net	431,132	404,875
Population Health [Member] | Netsmart Acquisition [Member]
Goodwill [Line Items]
Additions arising from business acquisitions		0
Population Health [Member] | HealthMEDX, LLC [Member]
Goodwill [Line Items]
Additions arising from business acquisitions		0
Population Health [Member] | DeVero Acquisition [Member]
Goodwill [Line Items]
Additions arising from business acquisitions	0
Population Health [Member] | NantHealth, Inc. [Member]
Goodwill [Line Items]
Additions arising from business acquisitions	13,350
Population Health [Member] | Enterprise Information Solutions [Member]
Goodwill [Line Items]
Increase in the residual allocation to goodwill	12,860
Netsmart [Member]
Goodwill [Line Items]
Goodwill	675,340	0
Additions arising from business acquisitions	36,866	637,740
Other additions	4,503	0
Reallocation		37,600
Foreign exchange translation	0	0
Goodwill, net	712,206	675,340
Netsmart [Member] | Netsmart Acquisition [Member]
Goodwill [Line Items]
Additions arising from business acquisitions		619,283
Netsmart [Member] | HealthMEDX, LLC [Member]
Goodwill [Line Items]
Additions arising from business acquisitions		$ 18,457
Netsmart [Member] | DeVero Acquisition [Member]
Goodwill [Line Items]
Additions arising from business acquisitions	32,363
Netsmart [Member] | NantHealth, Inc. [Member]
Goodwill [Line Items]
Additions arising from business acquisitions	0
Netsmart [Member] | Enterprise Information Solutions [Member]
Goodwill [Line Items]
Increase in the residual allocation to goodwill	$ 0