Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock option exercises/deferred stock unit conversions, shares	408,563	399,224	548,238
Stock Redeemed or Called During Period, Shares	6,000,000
Stock Issued During Period, Shares, New Issues	150,000
Treasury Stock, Shares, Acquired	206,951	716,062	1,037,982
Stock Issued During Period, Shares, Treasury Stock Reissued	140,264
Preferred Stock, Dividends Per Share, Declared	$ 0.34	$ 1.34	$ 1.34
Common Stock, Dividends, Per Share, Cash Paid	$ 2.85	$ 2.80	$ 2.58