Condensed Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Statement Of Stockholders Equity [Abstract]
Dividends on common stock, per share	$ 0.41	$ 0.41	$ 0.41	$ 0.40	$ 0.40	$ 0.40