Components of Deferred Tax Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets
Accruals and reserves, net	$ 16,925	$ 14,006
Allowance for doubtful accounts	14,931	5,853
Stock-based compensation, net	7,309	6,839
Deferred compensation	151	148
Deferred revenue	6,205	0
Net operating loss carryforwards	63,256	93,474
Research and development tax credit	15,573	16,253
AMT credits	7,532	3,400
Other	10,330	9,443
Less: Valuation allowance	(832)	0
Total deferred tax assets	141,380	149,416
Deferred tax liabilities
Prepaid expense	(16,664)	(13,094)
Property and equipment, net	(1,344)	(2,220)
Acquired intangibles, net	(185,257)	(205,775)
Deferred revenue	0	(2,438)
Total deferred tax liabilities	(203,265)	(223,527)
Net deferred tax liabilities	$ (61,885)	$ (74,111)