Accounts Receivable - Allowance for Doubtful Accounts Related to Accounts Receivable (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Allowance for doubtful accounts beginning of period	$ 32,506	$ 21,903
Provision for bad debts	27,648	13,729	[1]
Write-offs	(12,318)	(10,396)
Allowance for doubtful accounts end of period	$ 47,836	$ 25,236

[1] Reflects the impact of the Company's adoption of Accounting Standards Update 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, to simplify several aspects of the accounting for share-based compensation, including the income tax consequences.