Shareholders' Equity - Shares Repurchased (Details) - USD ($)	1 Months Ended	3 Months Ended							9 Months Ended		10 Months Ended	12 Months Ended
	Nov. 04, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Nov. 04, 2021	Dec. 31, 2020	Aug. 04, 2021
Equity, Class of Treasury Stock [Line Items]
Repurchases of common stock									$ 305,000,000	$ 320,000,000
Common Shares
Equity, Class of Treasury Stock [Line Items]
Repurchase authorized amount													$ 350,000,000
Shares repurchased (in shares)		2,918,993	1,887,531	1,986,534	4,344,649	1,857,323	5,956,422	3,629,410				15,787,804
Repurchases of common stock		$ 140,000,000	$ 88,000,000	$ 77,000,000	$ 126,000,000	$ 40,000,000	$ 164,000,000	$ 116,000,000				$ 446,000,000
Average price paid per share (in dollars per share)		$ 47.76	$ 46.63	$ 38.83	$ 28.87	$ 21.72	$ 27.49	$ 32.03				$ 28.23
Common Shares | Subsequent Event
Equity, Class of Treasury Stock [Line Items]
Remaining capacity of shares repurchase program	$ 220,000,000										$ 220,000,000
Shares repurchased (in shares)	1,498,751										8,291,809
Repurchases of common stock	$ 77,000,000										$ 382,000,000
Average price paid per share (in dollars per share)	$ 51.90										$ 46.11