Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Additional paid-in capital	Treasury stock	Retained earnings	Accumulated other comprehensive income (loss)
Beginning of period (in shares) at Sep. 30, 2017			33,464,000
Exercise of stock options and vesting of other stock awards (in shares)			500,000
Treasury shares purchased (in shares)			(671,000)
End of period (in shares) at Mar. 31, 2018			33,293,000
Beginning of period at Sep. 30, 2017		$ 1,025,939	$ 519	$ 555,297	$ (574,104)	$ 1,049,206	$ (4,979)
Exercise of stock options and vesting of other stock awards			5
Share-based compensation expense				8,420
Exercise of stock options and vesting of other stock awards, including tax benefits				3,818
Treasury shares purchased					(41,159)
Net income (loss)		(86,203)				(86,203)
Other comprehensive income (loss)		9,683					9,683
End of period at Mar. 31, 2018		920,503	$ 524	567,535	(615,263)	963,003	4,704
Beginning of period (in shares) at Dec. 30, 2017			33,607,000
Exercise of stock options and vesting of other stock awards (in shares)			199,000
Treasury shares purchased (in shares)			(513,000)
End of period (in shares) at Mar. 31, 2018			33,293,000
Beginning of period at Dec. 30, 2017		933,848	$ 522	567,562	(583,651)	950,713	(1,298)
Exercise of stock options and vesting of other stock awards			2
Share-based compensation expense				4,524
Exercise of stock options and vesting of other stock awards, including tax benefits				(4,551)
Treasury shares purchased					(31,612)
Net income (loss)		12,290				12,290
Other comprehensive income (loss)		6,002					6,002
End of period at Mar. 31, 2018		$ 920,503	$ 524	567,535	(615,263)	963,003	4,704
Cumulative effect adjustment for adoption of new accounting pronouncement	[1]					7,815
Beginning of period (in shares) at Sep. 29, 2018		31,838,000	31,838,000
Exercise of stock options and vesting of other stock awards (in shares)			265,000
Treasury shares purchased (in shares)			(1,862,000)
End of period (in shares) at Mar. 30, 2019		30,241,000	30,241,000
Beginning of period at Sep. 29, 2018		$ 921,143	$ 526	581,488	(711,138)	1,062,246	(11,979)
Exercise of stock options and vesting of other stock awards			2
Share-based compensation expense				9,929
Exercise of stock options and vesting of other stock awards, including tax benefits				(5,138)
Treasury shares purchased					(106,297)
Net income (loss)		46,984				46,984
Other comprehensive income (loss)		1,006					1,006
End of period at Mar. 30, 2019		$ 875,444	$ 528	586,279	(817,435)	1,117,045	(10,973)
Beginning of period (in shares) at Dec. 29, 2018			30,992,000
Exercise of stock options and vesting of other stock awards (in shares)			241,000
Treasury shares purchased (in shares)			(992,000)
End of period (in shares) at Mar. 30, 2019		30,241,000	30,241,000
Beginning of period at Dec. 29, 2018		$ 905,163	$ 526	587,011	(761,189)	1,092,287	(13,472)
Exercise of stock options and vesting of other stock awards			2
Share-based compensation expense				5,176
Exercise of stock options and vesting of other stock awards, including tax benefits				(5,908)
Treasury shares purchased					(56,246)
Net income (loss)		24,758				24,758
Other comprehensive income (loss)		2,499					2,499
End of period at Mar. 30, 2019		$ 875,444	$ 528	$ 586,279	$ (817,435)	$ 1,117,045	$ (10,973)

[1] See Note 1, "Basis of Presentation," for a discussion of recently adopted accounting pronouncements.