Acquisitions - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed at Acquisition (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Nov. 02, 2015	Oct. 31, 2015	Jun. 01, 2015	Dec. 31, 2014	Nov. 03, 2014	Sep. 02, 2014	Jun. 13, 2014	Apr. 21, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
GOODWILL	$ 1,915,690				$ 1,884,920					$ 1,671,205
Sharp School [Member]
Business Acquisition [Line Items]
Working Capital				$ (1,042)
Property and equipment				782
Other assets, net				77
Intangible assets				9,092
GOODWILL				8,254
Total assets acquired				17,163
Net assets acquired				$ 17,163
School Reach [Member]
Business Acquisition [Line Items]
Working Capital						$ (2,073)
Property and equipment						342
Intangible assets						7,350
GOODWILL						6,923
Total assets acquired						12,542
Net assets acquired						$ 12,542
Health Advocate [Member]
Business Acquisition [Line Items]
Working Capital								$ 1,373
Property and equipment								7,439
Other assets, net								72
Intangible assets								151,990
GOODWILL								156,014
Total assets acquired								316,888
Non-current deferred taxes								43,034
Long-term liabilities								7,964
Total liabilities assumed								50,998
Net assets acquired								$ 265,890
911 Enable [Member]
Business Acquisition [Line Items]
Working Capital							$ 596
Property and equipment							59
Intangible assets							20,685
GOODWILL							21,289
Total assets acquired							42,629
Long-term liabilities							258
Total liabilities assumed							258
Net assets acquired							$ 42,371
School Messenger [Member]
Business Acquisition [Line Items]
Working Capital									$ (9,751)
Property and equipment									1,574
Intangible assets									40,145
GOODWILL									50,386
Total assets acquired									82,354
Non-current deferred taxes									4,231
Long-term liabilities									751
Total liabilities assumed									4,982
Net assets acquired									$ 77,372
ClientTell [Member]
Business Acquisition [Line Items]
Working Capital		$ 503
Property and equipment		429
Other assets, net		2
Intangible assets		26,300
GOODWILL		14,967
Total assets acquired		42,201
Long-term liabilities		3,828
Total liabilities assumed		3,828
Net assets acquired		$ 38,373
Magnetic North [Member]
Business Acquisition [Line Items]
Working Capital			$ 243
Property and equipment			574
Intangible assets			16,361
GOODWILL			24,579
Total assets acquired			41,757
Non-current deferred taxes			3,050
Total liabilities assumed			3,050
Net assets acquired			$ 38,707