Other Income (Additional Information) (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Other Income Expense [Line Items]
Carrying value of investments				$ 0
Proceeds from sales of cost-based investments	400,000	800,000	1,165,000
Ziplist Cost Method Investment [Member]
Other Income Expense [Line Items]
Realized gain on sale of investments			800,000
Pingg Cost Method Investment [Member]
Other Income Expense [Line Items]
Realized gain on sale of investments			$ 400,000