Accrued Liabilities and Deferred Credits (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accrued Liabilities And Deferred Credits [Line Items]
Accrued compensation	$ 4,983	$ 2,673
Deferred revenue	15,484	15,309
Membership deposits	7,731	8,426
Accruals for fees and expenses for the SEC investigation	5,781	0
Other accrued liabilities	9,447	5,651
Total accrued liabilities and deferred credits	44,139	34,911
Special Purpose Entities
Accrued Liabilities And Deferred Credits [Line Items]
Accrued interest expense for Senior Notes held by special purpose entity	$ 713	$ 2,852