Acquisitions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands						1 Months Ended	3 Months Ended								12 Months Ended
	Nov. 16, 2015	Sep. 01, 2015	Aug. 18, 2015	Jul. 08, 2015	Nov. 30, 2014	Oct. 31, 2013	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Revenue							$ 300,888	$ 280,894	$ 212,768	$ 205,735	$ 200,731	$ 192,598	$ 188,722	$ 185,810	$ 1,000,285	$ 767,861	$ 712,702
Primatics Financial [Member]
Business Acquisition [Line Items]
Consideration paid, net of cash plus the costs of transaction	$ 127,600														$ 115,181
Business acquisition, effective date of acquisition															Nov. 16, 2015
Revenue															$ 6,500
Primatics Financial [Member] | Doubtful [Member]
Business Acquisition [Line Items]
Fair value of acquired accounts receivable							400								$ 400
Primatics Financial [Member] | Completed Technology [Member]
Business Acquisition [Line Items]
Amortized period															10 years
Primatics Financial [Member] | Customer Relationships [Member] | Minimum [Member]
Business Acquisition [Line Items]
Amortized period															1 year
Primatics Financial [Member] | Customer Relationships [Member] | Maximum [Member]
Business Acquisition [Line Items]
Amortized period															15 years
Primatics Financial [Member] | Trade Name [Member]
Business Acquisition [Line Items]
Amortized period															10 years
Varden [Member]
Business Acquisition [Line Items]
Consideration paid, net of cash plus the costs of transaction		$ 25,300													$ 23,134
Business acquisition, effective date of acquisition															Sep. 01, 2015
Revenue															$ 2,500
Varden [Member] | Completed Technology [Member]
Business Acquisition [Line Items]
Amortized period															8 years
Varden [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortized period															10 years
Varden [Member] | Trade Name [Member]
Business Acquisition [Line Items]
Amortized period															10 years
Varden [Member] | Non-Compete Agreement [Member]
Business Acquisition [Line Items]
Amortized period															3 years
Advent [Member]
Business Acquisition [Line Items]
Consideration paid, net of cash plus the costs of transaction				$ 2,600,000											$ 2,596,532
Business acquisition, effective date of acquisition															Jul. 08, 2015
Revenue															$ 155,800
Business acquisition, share price				$ 44.25
Non-cash consideration related to fair value of unvested acquired equity awards															11,800
Advent [Member] | Doubtful [Member]
Business Acquisition [Line Items]
Fair value of acquired accounts receivable							2,600								$ 2,600
Advent [Member] | Completed Technology [Member]
Business Acquisition [Line Items]
Amortized period															12 years
Advent [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Amortized period															12 years
Advent [Member] | Trade Name [Member]
Business Acquisition [Line Items]
Amortized period															10 years
DSTGS [Member]
Business Acquisition [Line Items]
Consideration paid, net of cash plus the costs of transaction					$ 95,000										$ 94,962
Business acquisition, effective date of acquisition															Nov. 30, 2014
Working capital adjustment paid in second quarter of 2015									$ 7,900
DSTGS [Member] | Doubtful [Member]
Business Acquisition [Line Items]
Fair value of acquired accounts receivable							$ 500								$ 500
DSTGS [Member] | Completed Technology [Member] | Minimum [Member]
Business Acquisition [Line Items]
Amortized period															7 years
DSTGS [Member] | Completed Technology [Member] | Maximum [Member]
Business Acquisition [Line Items]
Amortized period															8 years
DSTGS [Member] | Customer Relationships [Member] | Minimum [Member]
Business Acquisition [Line Items]
Amortized period															10 years
DSTGS [Member] | Customer Relationships [Member] | Maximum [Member]
Business Acquisition [Line Items]
Amortized period															15 years
DSTGS [Member] | Trade Name [Member]
Business Acquisition [Line Items]
Amortized period															10 years
Prime [Member]
Business Acquisition [Line Items]
Consideration paid, net of cash plus the costs of transaction						$ 4,000
Citigroup's Alternative Investor Services [Member]
Business Acquisition [Line Items]
Consideration paid, net of cash plus the costs of transaction			$ 425,000
Business acquisition, effective date of acquisition															Aug. 18, 2015