Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Share data in Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Consolidated Statements of Income (Unaudited) [Abstract]
Revenue	$ 671,061	$ 541,305
Cost of sales	106,644	90,045
Gross profit	564,417	451,260
Operating expenses:
Selling expenses	313,101	233,094
General and administrative expenses	150,119	135,507
Total operating expenses	463,220	368,601
Operating income	101,197	82,659
Other income (expense), net	(3,604)	112
Income before provision for income taxes	97,593	82,771
Provision for income taxes	33,332	28,489
Net income	$ 64,261	$ 54,282
Net income per share (Note 2):
Basic (in dollars per share)	$ 1.09	$ 0.93
Diluted (in dollars per share)	$ 1.05	$ 0.90
Weighted-average common shares outstanding (000s):
Basic (in shares)	58,869	58,352
Diluted (in shares)	61,227	60,566