Shareholders' Equity (Narrative) (Details) - USD ($)		1 Months Ended				3 Months Ended		9 Months Ended		62 Months Ended
	Jul. 29, 2016	Nov. 30, 2021	Jul. 31, 2021	Apr. 30, 2021	Feb. 28, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Aug. 31, 2021	May 31, 2021	Mar. 31, 2021
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, repurchased cost						$ 20,000,000.0		$ 50,000,000.0	$ 34,400,000
Quarterly dividends declared			$ 0.21	$ 0.21	$ 0.21
Dividends declared						$ 0.21	$ 0.20	$ 0.63	$ 0.60
Dividends payable, date to be paid, year and month											2021-08	2021-05	2021-03
Scenario Forecast [Member]
Equity Class Of Treasury Stock [Line Items]
Dividends declared		$ 0.231
Dividends payable, date to be paid, year and month		2021-11
Common Stock
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, expiration date	Dec. 31, 2023
Stock repurchase program, remaining authorized repurchase amount						$ 543,800,000		$ 543,800,000		$ 543,800,000
Shares repurchase program, shares repurchased						(186,929)		(507,022)	(382,170)
Common Stock | Share Repurchase Program Excluding Accelerated Share Repurchase
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, shares repurchased						200,000		500,000
Shares repurchase program, repurchased cost						$ 20,000,000.0		$ 50,000,000.0
Shares repurchase program, average price per share						$ 106.99		$ 98.61
Common Stock | Share Repurchase Program Including Accelerated Share Repurchase
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, shares repurchased										10,200,000
Shares repurchase program, repurchased cost										$ 656,200,000
Shares repurchase program, average price per share										$ 64.15
Common Stock | Maximum [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program, authorized amount	$ 1,200,000,000.0