Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2015

Summary of Significant Accounting Policies

Schedule of Annual Dues Deferred Revenue

	Balance at beginning of period		New billings		Revenue recognized		Balance at end of period
Year ended December 31, 2015	$	12,912	$	31,952	$	(31,758)	$	13,106
Year ended December 31, 2014		12,344		31,294		(30,726)		12,912
Year ended December 31, 2013		11,599		30,269		(29,524)		12,344

Schedule of Allowances Against Accounts and Notes Receivable

					Adjustments (to)/from
			Additions/charges		deferred revenue, net,
	Balance at		to cost and expense for		for accounts where
	beginning of period		allowances for doubtful accounts		collectability is remote		Deductions/write-offs		Balance at end of period
Year ended December 31, 2015	$	4,495	$	433	$	(80)	$	(365)	$	4,483
Year ended December 31, 2014		4,122		630		228		(485)		4,495
Year ended December 31, 2013		3,913		604		(160)		(235)		4,122