Earnings Per Share, Share Repurchases and Dividends on Common Stock (Unaudited) Earnings Per Share and Dividends (Details 1) - $ / shares shares in Millions	1 Months Ended		3 Months Ended
	May 31, 2020	May 31, 2019	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share, Basic and Diluted [Abstract]
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements			0.4	0.7
Common stock dividends per share, declared (in dollars per share)	$ 1.45	$ 1.32	$ 1.45	$ 1.32
Increase in quarterly common stock dividend (percent)	10.00%