Description of business and basis of consolidation and presentation (Details 3) (2013 Results of Adjustments, USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended					6 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Results of Adjustments [Line Items]
Correction of Error - Net Revenues						$ 8
Correction of Error - Interest and Other Investment Income (Expense)						1
Correction of Error - Income Before Income Tax Expense						9
Correction of Error - Net Income	1	1	1	1	1	7		4	2	1
Correction of Error - Accrued Expenses and Other Liabilities						9
Correction of Error - Operating Cash Flows							(9)
Correction of Error - Basic and Diluted EPS						$ (0.01)
Online
Results of Adjustments [Line Items]
Correction of Error - Net Revenues						8
Correction of Error - Income Before Income Tax Expense						9
Europe
Results of Adjustments [Line Items]
Correction of Error - Net Revenues						8
Correction of Error - Income Before Income Tax Expense						9
Blizzard
Results of Adjustments [Line Items]
Correction of Error - Net Revenues						8
Correction of Error - Income Before Income Tax Expense						$ 9