Property and Equipment by Geographic Area (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	$ 52,253	$ 45,638
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	36,716	30,917
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	3,532	3,077
India
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	3,392	3,092
France
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	2,378	2,388
Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	2,087	1,843
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	1,253	1,447
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	753	938
Other European
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	1,173	957
Other International
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment	$ 969	$ 979