Summary of Significant Accounting Policies - Allowance for Doubtful Accounts and Credit Memo Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Valuation Allowance [Line Items]
The general period to charge-off uncollectible balances of receivable, as circumstances warrant, is no later than this period of time past due	1 year
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowance, balance at the beginning of the year	$ 32,141	$ 34,645	$ 25,209
Credit Memos Charged to Revenue	42,497	47,137	49,483
Allowance for Bad Debts Charged to Expense	15,326	14,209	11,321
Other	(4,511)	(572)	3,612
Deductions	(54,006)	(63,278)	(54,980)
Valuation allowance, balance at the end of the year	$ 31,447	$ 32,141	$ 34,645