Summary of Significant Accounting Policies - Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Accounts receivable, gross	$ 4,971	$ 6,206
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance Beginning of the Year	2,511	2,309	$ 3,249
Additions	11,237	9,826	8,335
Write-offs Net of Recoveries	(10,615)	(9,624)	(9,275)
Balance at End of Year	$ 3,133	$ 2,511	$ 2,309