Accounts Payable and Accrued Expenses (Accounts Payable and Accrued Expenses) (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts Payable and Accrued Liabilities [Abstract]
Trade payables and accrued expenses	$ 35,767	$ 22,608
Sales commissions payable	22,598	13,186
Dividends payable	13,831	13,719
Accrued payroll and related taxes	16,948	10,409
Coach incentive accruals	325	5,598
Promotional sales incentive accruals	7,621	4,818
Deferred revenue	7,606	4,333
Sales tax payable	2,981	1,549
Total	$ 107,677	$ 76,220