Shareholders' Equity - Common Stock Repurchased and Retired Table (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended	12 Months Ended
	Sep. 30, 2020	Aug. 31, 2020	Jul. 31, 2020	Sep. 30, 2020	Sep. 30, 2020
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Shares	0	357,644	0		799,495
Treasury Stock Acquired, Average Cost Per Share	$ 0	$ 139.79	$ 0		$ 125.10
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 1,272,511	$ 1,272,511	$ 1,322,518	$ 1,272,511	$ 1,272,511
Cost of Issuance of Treasury Stock, Shares				15,434
October Twenty Six Two Thousand Ten Program and Cost of Issuance of Treasury Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Shares	0	373,078	0