Stockholders' Equity (Summary Of Stock-Based Compensation Expense) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense, net of tax	$ 15,705	$ 7,296	$ 43,505	$ 19,726
Stock-based compensation expense before income taxes	15,705	7,296	43,505	19,726
Income tax benefit	(5,228)	(3,064)	(16,066)	(8,118)
Total stock-based compensation after income taxes	10,477	4,232	27,439	11,608
Fulfillment Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense, net of tax	206	323	1,446	806
Technology And Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense, net of tax	7,522	2,694	19,819	6,939
Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense, net of tax	1,539	777	4,273	2,176
General And Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense, net of tax	$ 6,438	$ 3,502	$ 17,967	$ 9,805