Earnings Per Share, Share Repurchases and Dividends on Common Stock (Unaudited) (Details 2) - $ / shares shares in Millions	1 Months Ended			3 Months Ended		9 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share, Basic and Diluted [Abstract]
Dilutive effect of of stock awards and options granted to employees under stock-based compensation plans				2.1	3.0	2.2	3.2
Common stock dividends per share, declared (in dollars per share)	$ 0.80	$ 0.70	$ 0.61			$ 2.3	$ 2.01
Increase in quarterly common stock dividend (percent)	14.00%	15.00%