Schedule of Amortizable Intangible Assets (Detail) - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Goodwill and Other Intangible Assets [Line Items]
Cost		$ 127,446	$ 127,467
Accumulated Amortization		(101,229)	(95,568)
Net Book Value	[1]	26,217	31,899
Client related intangibles
Goodwill and Other Intangible Assets [Line Items]
Cost		63,143	63,164
Accumulated Amortization		(48,033)	(44,835)
Net Book Value	[1]	15,110	18,329
Technology
Goodwill and Other Intangible Assets [Line Items]
Cost		58,942	58,942
Accumulated Amortization		(47,835)	(45,372)
Net Book Value	[1]	11,107	13,570
Other intangibles
Goodwill and Other Intangible Assets [Line Items]
Cost		5,361	5,361
Accumulated Amortization		$ (5,361)	$ (5,361)
Minimum | Client related intangibles
Goodwill and Other Intangible Assets [Line Items]
Useful Lives		9 years	9 years
Minimum | Technology
Goodwill and Other Intangible Assets [Line Items]
Useful Lives		7 years	7 years
Maximum | Client related intangibles
Goodwill and Other Intangible Assets [Line Items]
Useful Lives		10 years	10 years
Maximum | Technology
Goodwill and Other Intangible Assets [Line Items]
Useful Lives		10 years	10 years

[1] Included in other long-term assets in the unaudited condensed consolidated balance sheets.