Earnings Per Share, Share Repurchases and Dividends on Common Stock (Unaudited) (Details 2) - $ / shares shares in Millions	1 Months Ended		3 Months Ended
	May. 31, 2015	May. 31, 2014	Mar. 31, 2016	Mar. 31, 2015
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	2.8
Common stock dividends per share, declared (in dollars per share)	$ 0.80	$ 0.70	$ 0.8	$ 0.7
Increase in quarterly common stock dividend (percent)	14.00%