Acquisitions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended					9 Months Ended
	Jul. 01, 2015	Feb. 12, 2015	Jan. 01, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Acquisition Date [Line Items]
Acquisition date fair value based on closing price				$ 62.53					$ 62.53
Net Revenue				$ 209,881				$ 198,049	$ 621,378	$ 618,185
Operating income				36,825				21,277	81,685	97,119
Amortization expenses for intangible assets				8,300				$ 2,800	22,000	$ 8,300
Goodwill				806,801			$ 567,146		806,801
Studer Group
Acquisition Date [Line Items]
Effective date of acquisition		Feb. 12, 2015
Outstanding stock from the existing shareholders		100.00%
Date of acquisition agreement		Jan. 26, 2015
Acquisition date fair value of the consideration		$ 325,186
Borrowings under credit facility		$ 102,000
Common stock issued		28,486
Acquisition date fair value		$ 2,204
Acquisition date fair value based on closing price		$ 77.35
Weighted-average amortization period		6 years 3 months 18 days
Goodwill expected to be deductible for income tax purpose		$ 119,500
Net Revenue				22,300					56,000
Operating income				1,600					3,600
Amortization expenses for intangible assets				$ 6,100					$ 15,200
Expenses incurred		2,100			$ 200	$ 1,000	$ 900
Cash		323,237
Intangible Asset		97,500
Goodwill		$ 232,676
Sky Analytics Inc
Acquisition Date [Line Items]
Acquisition date fair value of the consideration			$ 9,700
Cash			8,800
Fair value of contingent consideration			900
Intangible Asset			2,000
Goodwill			$ 7,400
Rittman Mead [Member]
Acquisition Date [Line Items]
Acquisition date fair value of the consideration	$ 1,200