Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Consolidated Statements of Income (Unaudited) [Abstract]
Revenue	$ 424,426	$ 388,362	$ 820,271	$ 752,486
Cost of sales	71,168	67,937	171,822	132,770
Gross profit	353,258	320,425	648,449	619,716
Operating expenses:
Selling expenses	183,500	160,739	352,642	315,001
General and administrative expenses	103,712	100,525	204,854	199,437
Total operating expenses	287,212	261,264	557,496	514,438
Operating income	66,046	59,161	90,953	105,278
Other income (expense), net	(127)	(7,287)	(549)	(6,673)
Income before provision for income taxes	65,919	51,874	90,404	98,605
Provision for income taxes	24,218	19,482	33,395	35,173
Net income	$ 41,701	$ 32,392	$ 57,009	$ 63,432
Net income per share (Note 2):
Basic (in dollars per share)	$ 0.67	$ 0.51	$ 0.92	$ 1.01
Diluted (in dollars per share)	$ 0.65	$ 0.50	$ 0.89	$ 0.98
Weighted-average common shares outstanding (000s):
Basic (in shares)	61,806	62,919	61,817	62,698
Diluted (in shares)	64,193	65,072	64,177	64,904