Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) Vendor Agreement	Dec. 31, 2015 USD ($) Vendor	Dec. 31, 2014 USD ($) Vendor
Significant Accounting Policies [Line Items]
Deferred revenue	$ 26,131,000	$ 26,733,000
Membership enrollment fees recognition period	2 years
Membership fees recognition period	12 months
Equipment deposits	$ 2,170,000	5,587,000
Cost of revenue	122,317,000	113,492,000	$ 100,306,000
Selling, general and administrative	50,008,000	55,573,000	35,121,000
Impairment charges	$ 0	0
Income tax positions	Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized.
Number of tax receivable agreements | Agreement	2
Applicable tax savings	85.00%
Percentage of remaining tax savings	15.00%
Income tax rate maximum tax liability	3.50%
Direct TSG Investors and TRA Holders [Member]
Significant Accounting Policies [Line Items]
Liability payable under tax benefit obligations	$ 419,071,000
Selling, General and Administrative Expenses [Member]
Significant Accounting Policies [Line Items]
Advertising expenses	8,270,000	9,349,000	7,272,000
Point of Sale System [Member]
Significant Accounting Policies [Line Items]
Cost of revenue	0	1,236,000	3,385,000
Placement Services [Member]
Significant Accounting Policies [Line Items]
Selling, general and administrative	3,974,000	3,452,000	$ 2,743,000
Area Development Agreements [Member]
Significant Accounting Policies [Line Items]
Deferred revenue	10,026,000	10,471,000
Franchise Fees [Member]
Significant Accounting Policies [Line Items]
Deferred revenue	$ 260,000	$ 473,000
Individual Franchise Agreements [Member]
Significant Accounting Policies [Line Items]
Franchisee initial term	10 years
Equipment Purchase [Member] | Supplier Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Number of vendors | Vendor	2	2	2
Equipment Purchase [Member] | Supplier Concentration Risk [Member] | Vendor One [Member]
Significant Accounting Policies [Line Items]
Purchases from vendor	83.00%	79.00%	66.00%
Equipment Purchase [Member] | Supplier Concentration Risk [Member] | Vendor Two [Member]
Significant Accounting Policies [Line Items]
Purchases from vendor	13.00%	18.00%	25.00%
Advertising Purchase [Member] | Supplier Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Number of vendors | Vendor	2	2	2
Advertising Purchase [Member] | Supplier Concentration Risk [Member] | Vendor One [Member]
Significant Accounting Policies [Line Items]
Purchases from vendor	25.00%	49.00%	61.00%
Advertising Purchase [Member] | Supplier Concentration Risk [Member] | Vendor Two [Member]
Significant Accounting Policies [Line Items]
Purchases from vendor	16.00%	0.00%	0.00%
Maximum [Member]
Significant Accounting Policies [Line Items]
Insured amount	$ 250,000,000
Maximum [Member] | Area Development Agreements [Member]
Significant Accounting Policies [Line Items]
Franchisee initial term	10 years
Maximum [Member] | Transfer Fees [Member]
Significant Accounting Policies [Line Items]
Deferred revenue	$ 25,000
Minimum [Member] | Area Development Agreements [Member]
Significant Accounting Policies [Line Items]
Franchisee initial term	5 years
Minimum [Member] | Transfer Fees [Member]
Significant Accounting Policies [Line Items]
Deferred revenue	$ 10,000