Accounts Payable and Accrued Expenses (Accounts Payable and Accrued Expenses) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts Payable and Accrued Liabilities [Abstract]
Trade payables and accrued expenses	$ 22,608	$ 19,017
Sales commissions payable	13,186	10,626
Dividends payable	13,719	9,137
Accrued payroll and related taxes	10,409	8,309
Coach incentive accruals	5,598	5,546
Promotional sales incentive accruals	4,818	3,817
Deferred revenue	4,333	2,797
Sales tax payable	1,549	1,074
Total	$ 76,220	$ 60,323