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		9 Months Ended
	May 31, 2021	May 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share, Basic and Diluted [Abstract]
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements			0.6	0.5	0.5	0.6
Common stock dividends per share, declared (in dollars per share)	$ 1.57	$ 1.45			$ 4.59	$ 4.22
Increase in quarterly common stock dividend (percent)	8.00%