Accounts Receivable - Activity in Accounts Receivable Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	$ 7,364	$ 9,023	$ 3,703
Charges to income from operations	49,677	37,870	32,293
Collections from cash basis customers	(50,896)	(39,529)	(26,973)
Ending balance	$ 6,145	$ 7,364	$ 9,023