Stock-Based Compensation (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before income taxes	$ 104	$ 110	$ 126
Stock-based compensation expense, income tax benefit	(38)	(40)	(46)
Total stock-based compensation expense, net of income tax benefit	66	70	80
Cost of sales - online
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before income taxes	1	0	0
Cost of sales - software royalties and amortization
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before income taxes	17	17	9
Product development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before income taxes	22	33	20
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before income taxes	8	7	8
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense before income taxes	$ 56	$ 53	$ 89