Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Stockholders Equity [Abstract]
Cash dividends paid per common share	$ 1.95	$ 1.91	$ 1.87
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01