Long-Lived Assets by Geographic Region (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total long-lived assets	$ 57,897	$ 44,042
United States
Segment Reporting Information [Line Items]
Total long-lived assets	31,835	28,626
Israel
Segment Reporting Information [Line Items]
Total long-lived assets	23,883	13,167
United Kingdom
Segment Reporting Information [Line Items]
Total long-lived assets	$ 2,179	$ 2,249