Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Share data in Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Consolidated Statements of Income (Unaudited) [Abstract]
Revenue	$ 650,027	$ 671,328	$ 1,321,088	$ 1,212,633
Cost of sales	156,010	111,273	262,654	201,318
Gross profit	494,017	560,055	1,058,434	1,011,315
Operating expenses:
Selling expenses	283,575	297,170	596,676	530,264
General and administrative expenses	155,705	148,302	305,824	283,809
Total operating expenses	439,280	445,472	902,500	814,073
Operating income	54,737	114,583	155,934	197,242
Other income (expense), net	(21,119)	(1,187)	(38,627)	(1,075)
Income before provision for income taxes	33,618	113,396	117,307	196,167
Provision for income taxes	14,111	38,961	42,946	67,450
Net income	$ 19,507	$ 74,435	$ 74,361	$ 128,717
Net income per share (Note 2):
Basic (in dollars per share)	$ 0.33	$ 1.27	$ 1.26	$ 2.20
Diluted (in dollars per share)	$ 0.32	$ 1.22	$ 1.22	$ 2.11
Weighted-average common shares outstanding (000s):
Basic (in shares)	59,052	58,620	58,961	58,487
Diluted (in shares)	61,118	61,121	61,177	60,882