Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statements of Income [Abstract]
Revenue	$ 2,169,664	$ 1,743,991	$ 1,537,259
Cost of sales	353,152	322,624	272,431
Gross profit	1,816,512	1,421,367	1,264,828
Operating expenses:
Selling expenses	970,219	751,448	646,348
General and administrative expenses	505,449	436,177	401,418
Total operating expenses	1,475,668	1,187,625	1,047,766
Operating income	340,844	233,742	217,062
Other income (expense), net (Note 23)	4,398	(6,973)	(9,449)
Income before provision for income taxes	345,242	226,769	207,613
Provision for income taxes	123,597	73,439	71,562
Net income	$ 221,645	$ 153,330	$ 136,051
Net income per share:
Basic (in dollars per share)	$ 3.66	$ 2.47	$ 2.18
Diluted (in dollars per share)	$ 3.52	$ 2.38	$ 2.11
Weighted-average common shares outstanding (000s):
Basic (in shares)	60,600	62,066	62,370
Diluted (in shares)	63,025	64,546	64,547