Stockholders' Equity (Summary Of Stock-Based Compensation Expense) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Stock-based compensation expense before income taxes	$ 15,536	$ 6,928	$ 27,800	$ 12,430
Income tax benefit	(5,973)	(2,820)	(10,720)	(5,054)
Total stock-based compensation expense after income taxes	9,563	4,108	17,080	7,376
Fulfillment Expense [Member]
Stock-based compensation expense before income taxes	679	307	1,240	483
Technology And Development Expense [Member]
Stock-based compensation expense before income taxes	7,005	2,376	12,297	4,245
Marketing Expense [Member]
Stock-based compensation expense before income taxes	1,485	756	2,734	1,399
General And Administrative Expense [Member]
Stock-based compensation expense before income taxes	$ 6,367	$ 3,489	$ 11,529	$ 6,303