Summary of Significant Accounting Policies - Schedule of Annual Dues Deferred Revenue (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Deferred Revenue Arrangement [Line Items]
Revenue recognized	$ (596,000)	$ (628,000)	$ (376,000)
Annual Dues
Deferred Revenue Arrangement [Line Items]
Balance at beginning of period	11,599,000	11,874,000	12,212,000
New Billings	30,269,000	28,634,000	28,584,000
Revenue recognized	(29,524,000)	(28,909,000)	(28,922,000)
Balance at end of period	$ 12,344,000	$ 11,599,000	$ 11,874,000