Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Income [Abstract]
Revenue	$ 2,581,934	$ 2,420,416	$ 2,679,008
Cost of sales	658,028	581,420	634,140
Gross profit	1,923,906	1,838,996	2,044,868
Operating expenses:
Selling expenses	1,019,494	955,600	1,071,020
General and administrative expenses	646,848	615,970	662,302
Restructuring and impairment expenses	0	0	70,686
Total operating expenses	1,666,342	1,571,570	1,804,008
Operating income	257,564	267,426	240,860
Other income (expense), net (Note 17)	(1,332)	(12,254)	(21,194)
Income before provision for income taxes	256,232	255,172	219,666
Provision for income taxes	64,877	81,619	97,779
Net income	$ 191,355	$ 173,553	$ 121,887
Net income per share:
Basic (in dollars per share)	$ 3.66	$ 3.13	$ 2.21
Diluted (in dollars per share)	$ 3.63	$ 3.10	$ 2.16
Weighted-average common shares outstanding:
Basic (in shares)	52,296	55,518	55,170
Diluted (in shares)	52,765	55,927	56,476