Acquisitions - Purchase Price Allocation (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 31, 2013 Ruckus Sports LLC and UK Elite Soccer, Inc. [Member]
Cash				$ 1,991
Accounts receivable				637
Marketable securities				195
Prepaid expenses and other current assets				759
Property and equipment				69
Other assets				55
Accounts payable				(96)
Accrued liabilities and other current liabilities				(3,481)
Long-term liabilities				(53)
Total identifiable net assets acquired				76
Non-controlling interest				(2,896)
Goodwill	59,164	53,093	8,244	6,071
Net assets acquired				$ 3,251