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, 2019	May 31, 2018	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share, Basic and Diluted [Abstract]
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements			0.7	0.7
Common stock dividends per share, declared (in dollars per share)	$ 1.32	$ 1.20	$ 1.32	$ 1.20
Increase in quarterly common stock dividend (percent)	10.00%

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 28A
-URI http://asc.fasb.org/extlink&oid=117326831&loc=d3e1500-109256

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration