Summary of Significant Accounting Policies - AOCI and Concentrations of Credit Risk (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) club	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Accounting Policies [Line Items]
Number of stores | club	150
Foreign currency translation adjustment	$ (176,000)	$ (165,000)	$ (545,000)
Foreign currency translation adjustment, tax	0	0	0
Cash and cash equivalents held at one financial institution	20,965,000
Cash and cash equivalents	$ 45,596,000	$ 76,217,000	$ 93,452,000	$ 73,598,000
Switzerland Clubs [Member]
Accounting Policies [Line Items]
Number of stores | club	3