Basis and Summary of Significant Accounting Policies - Components of the Accounts Receivable Provision (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Accounting Policies [Abstract]
Bad Debt Expense	$ 118,749	$ 91,635
Provision for Returns and Uncollected Renewal Payments	23,393	28,045
Accounts Receivable Provision	$ 142,142	$ 119,680