Amortization Expense of Acquired Intangibles (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Amortization expense:
Total amortization expense	$ 11,137	$ 11,315	$ 7,701
Cost of software license
Amortization expense:
Total amortization expense	6,189	6,284	4,231
Selling and marketing
Amortization expense:
Total amortization expense	4,928	4,928	3,285
General and administrative
Amortization expense:
Total amortization expense	$ 20	$ 103	$ 185