Earnings Per Share, Share Repurchases and Dividends on Common Stock (Unaudited) (Details 2) - $ / shares shares in Millions	1 Months Ended			3 Months Ended		6 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share, Basic and Diluted [Abstract]
Dilutive effect of of stock awards and options granted to employees under stock-based compensation plans				1.4	1.9	1.7	2.3
Common stock dividends per share, declared (in dollars per share)	$ 0.90	$ 0.80	$ 0.70			$ 1.70	$ 1.50
Increase in quarterly common stock dividend (percent)	13.00%	14.00%