Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Additional paid-in capital	Treasury stock	Retained earnings	Accumulated other comprehensive (loss) income
Beginning of period (in shares) at Sep. 30, 2017			33,464,000
Exercise of stock options and vesting of other stock awards (in shares)			516,000
Treasury shares purchased (in shares)			(1,619,000)
End of period (in shares) at Jun. 30, 2018			32,361,000
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			6
Share-based compensation expense				13,206
Exercise of stock options and vesting of other stock awards, including tax benefits				4,056
Treasury shares purchased					(97,840)
Net income (loss)		(59,702)				(59,702)
Other comprehensive loss		(3,305)					(3,305)
End of period at Jun. 30, 2018		882,360	$ 525	572,559	(671,944)	989,504	(8,284)
Beginning of period (in shares) at Mar. 31, 2018			33,293,000
Exercise of stock options and vesting of other stock awards (in shares)			16,000
Treasury shares purchased (in shares)			(948,000)
End of period (in shares) at Jun. 30, 2018			32,361,000
Beginning of period at Mar. 31, 2018		920,503	$ 524	567,535	(615,263)	963,003	4,704
Exercise of stock options and vesting of other stock awards			1
Share-based compensation expense				4,786
Exercise of stock options and vesting of other stock awards, including tax benefits				238
Treasury shares purchased					(56,681)
Net income (loss)		26,501				26,501
Other comprehensive loss		(12,988)					(12,988)
End of period at Jun. 30, 2018		$ 882,360	$ 525	572,559	(671,944)	989,504	(8,284)
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)			295,000
Treasury shares purchased (in shares)			(2,646,000)
End of period (in shares) at Jun. 29, 2019		29,487,000	29,487,000
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			3
Share-based compensation expense				15,355
Exercise of stock options and vesting of other stock awards, including tax benefits				(4,527)
Treasury shares purchased					(150,704)
Net income (loss)		71,785				71,785
Other comprehensive loss		(79)					(79)
End of period at Jun. 29, 2019		$ 860,791	$ 529	592,316	(861,842)	1,141,846	(12,058)
Beginning of period (in shares) at Mar. 30, 2019			30,241,000
Exercise of stock options and vesting of other stock awards (in shares)			30,000
Treasury shares purchased (in shares)			(784,000)
End of period (in shares) at Jun. 29, 2019		29,487,000	29,487,000
Beginning of period at Mar. 30, 2019		$ 875,444	$ 528	586,279	(817,435)	1,117,045	(10,973)
Exercise of stock options and vesting of other stock awards			1
Share-based compensation expense				5,426
Exercise of stock options and vesting of other stock awards, including tax benefits				611
Treasury shares purchased					(44,407)
Net income (loss)		24,801				24,801
Other comprehensive loss		(1,085)					(1,085)
End of period at Jun. 29, 2019		$ 860,791	$ 529	$ 592,316	$ (861,842)	$ 1,141,846	$ (12,058)

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