Selected Segment Financial Data (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Revenues	$ 135,037	$ 112,149	$ 113,366	$ 104,543	$ 141,241	$ 97,017	$ 92,423	$ 87,743	$ 465,095	$ 418,424	$ 405,755
Depreciation and amortization expense									28,377	26,347	23,727
Stock-based compensation expense									11,254	7,790	7,645
Operating income (loss)	37,043	11,268	10,422	7,498	42,799	7,388	4,366	(905)	66,231	53,648	41,570
Americas
Segment Reporting Information [Line Items]
Revenues									245,703	221,560	222,952
Depreciation and amortization expense									11,139	9,903	12,373
Stock-based compensation expense									1,496	1,684	1,553
Operating income (loss)									84,662	74,791	69,350
EMEA
Segment Reporting Information [Line Items]
Revenues									164,874	150,525	137,061
Depreciation and amortization expense									4,473	3,731	1,954
Stock-based compensation expense									403	145	291
Operating income (loss)									46,889	43,274	31,083
Asia /Pacific
Segment Reporting Information [Line Items]
Revenues									54,518	46,339	45,742
Depreciation and amortization expense									3,410	3,126	1,300
Stock-based compensation expense									418	425	429
Operating income (loss)									6,774	(60)	6,293
Corporate
Segment Reporting Information [Line Items]
Depreciation and amortization expense									9,355	9,587	8,100
Stock-based compensation expense									8,937	5,536	5,372
Operating income (loss)									$ (72,094)	$ (64,357)	$ (65,156)