Amortization Expense of Acquired Intangibles (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 2,777	$ 2,805
Cost of software license
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	1,541	1,568
Selling and marketing
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	1,232	1,232
General and administrative
Acquired Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 4	$ 5