Acquisitions - Summary of the Purchase Price Allocation (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets:
Goodwill	$ 80,001	$ 78,954	$ 71,543
Intangible assets	4,815
Springboard Research [Member]
Assets:
Cash	85
Accounts receivable	561
Other current assets	285
Goodwill	3,695
Intangible assets	4,815
Total assets	9,441
Liabilities:
Accrued expenses	160
Deferred revenue	312
Total liabilities	472
Net assets acquired	$ 8,969