Sale of Building (Details) ft² in Thousands, $ in Thousands			1 Months Ended	12 Months Ended
	Dec. 23, 2015 USD ($)	Sep. 12, 2014 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2017 USD ($) ft²	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Leases [Abstract]
Gross proceeds from sale of building		$ 85,650
Area of new club lease (in sq ft) | ft²				24
Proceeds from building financing arrangement	$ 3,500		$ 500	$ 0	$ 0	$ 4,000
Gain on sale of building				$ 0	$ 0	$ 77,146