Subsequent Event (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2014
Subsequent Event [Line Items]
Treasury Stock, Shares, Acquired		22,475,816	8,168,318
Treasury Stock, Value, Acquired, Cost Method		$ 1,107	$ 443
Subsequent Event [Member]
Subsequent Event [Line Items]
Treasury Stock, Shares, Acquired	3,288,239
Treasury Stock, Value, Acquired, Cost Method	$ 153
Approved dividend, amount per share	$ 0.375
Estimated aggregate dividend payment	$ 418