Summary of Significant Accounting Policies (Details)	6 Months Ended
	Jun. 30, 2011
Summary of Significant Accounting Policies
Useful life of rental library product, low end of range (in months)	6
Useful life of rental library product, high end of range (in months)	24
Portion deferred subscriber fees period, low end of range (in months)	18
Portion deferred subscriber fees period, high end of range (in years)	5