Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Statement of Stockholders' Equity [Abstract]
Common treasury shares (in shares)	43,040,406	45,329,344	43,040,406	45,329,344	43,095,635	45,243,329	45,452,865	45,813,109
Cash dividends declared per common share (in dollars per share)	$ 0	$ 0.00	$ 0	$ 0.16