CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock:	Capital in Excess of Par:	Retained Earnings:	Accumulated Other Comprehensive Income (Loss):	Treasury Stock:
Beginning balance, common stock (in shares) at Sep. 30, 2020		39,914
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under stock plans (in shares)		273
Ending balance, common stock (in shares) at Mar. 31, 2021		40,187
Balance at beginning of period at Sep. 30, 2020		$ 40	$ 1,019,803	$ 553,718	$ (14,104)	$ (485,144)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			11,170
Exercise of stock options			6,693
Issuance of common stock under Employee Stock Purchase Plan			3,371
Issuance of restricted stock under Deposit Share Program			215
Net income (loss)	$ (118,278)			(118,278)
Dividends				(26,457)
Foreign currency translation adjustment	7,810				7,810
Cash flow hedges	15,430				15,430
Repurchases of common stock under Share Repurchase Program						(10,002)
Repurchases of common stock - other						(5,436)
Balance at end of period at Mar. 31, 2021	$ 958,829	$ 40	1,041,252	408,983	9,136	$ (500,582)
Beginning balance, treasure stock (in shares) at Sep. 30, 2020						10,834
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock under Share Repurchase Program (in shares)						67
Repurchase of commons stock - other (in shares)						37
Ending balance, treasury stock (in shares) at Mar. 31, 2021						10,938
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock (in dollars per share)	$ 0.90
Beginning balance, common stock (in shares) at Dec. 31, 2020		40,092
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under stock plans (in shares)		95
Ending balance, common stock (in shares) at Mar. 31, 2021		40,187
Balance at beginning of period at Dec. 31, 2020		$ 40	1,030,677	572,441	5,135	$ (499,565)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			5,319
Exercise of stock options			5,256
Net income (loss)	$ (149,808)			(149,808)
Dividends				(13,650)
Foreign currency translation adjustment	(13,815)				(13,815)
Cash flow hedges	17,816				17,816
Repurchases of common stock under Share Repurchase Program						(801)
Repurchases of common stock - other						(216)
Balance at end of period at Mar. 31, 2021	$ 958,829	$ 40	1,041,252	408,983	9,136	$ (500,582)
Beginning balance, treasure stock (in shares) at Dec. 31, 2020						10,931
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock under Share Repurchase Program (in shares)						5
Repurchase of commons stock - other (in shares)						2
Ending balance, treasury stock (in shares) at Mar. 31, 2021						10,938
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock (in dollars per share)	$ 0.46
Beginning balance, common stock (in shares) at Sep. 30, 2021		40,221
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under stock plans (in shares)		291
Ending balance, common stock (in shares) at Mar. 31, 2022		40,512
Balance at beginning of period at Sep. 30, 2021	$ 878,937	$ 40	1,052,869	431,968	4,791	$ (610,731)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			10,897
Exercise of stock options			13,122
Issuance of common stock under stock plans		1
Issuance of common stock under Employee Stock Purchase Plan			3,711
Net income (loss)	61,999			61,999
Dividends				(26,452)
Foreign currency translation adjustment	(14,009)				(14,009)
Cash flow hedges	30,199				30,199
Repurchases of common stock under Share Repurchase Program						(10,600)
Repurchases of common stock - other						(3,724)
Balance at end of period at Mar. 31, 2022	$ 944,081	$ 41	1,080,599	467,515	20,981	$ (625,055)
Beginning balance, treasure stock (in shares) at Sep. 30, 2021	11,795					11,795
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock under Share Repurchase Program (in shares)						79
Repurchase of commons stock - other (in shares)						26
Ending balance, treasury stock (in shares) at Mar. 31, 2022	11,900					11,900
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock (in dollars per share)	$ 0.92
Beginning balance, common stock (in shares) at Dec. 31, 2021		40,466
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under stock plans (in shares)		46
Ending balance, common stock (in shares) at Mar. 31, 2022		40,512
Balance at beginning of period at Dec. 31, 2021		$ 40	1,072,076	446,193	9,181	$ (624,670)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			4,894
Exercise of stock options			3,629
Issuance of common stock under stock plans		1
Net income (loss)	$ 34,571			34,571
Dividends				(13,249)
Foreign currency translation adjustment	(11,417)				(11,417)
Cash flow hedges	23,217				23,217
Repurchases of common stock - other						(385)
Balance at end of period at Mar. 31, 2022	$ 944,081	$ 41	$ 1,080,599	$ 467,515	$ 20,981	$ (625,055)
Beginning balance, treasure stock (in shares) at Dec. 31, 2021						11,898
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of commons stock - other (in shares)						2
Ending balance, treasury stock (in shares) at Mar. 31, 2022	11,900					11,900
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock (in dollars per share)	$ 0.46