Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		3 Months Ended							9 Months Ended
		Jun. 26, 2020	Mar. 27, 2020	Dec. 27, 2019	Jun. 28, 2019	Mar. 29, 2019		Dec. 28, 2018	Jun. 26, 2020	Jun. 28, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		$ 295,434	$ 272,131	$ 232,936	$ 158,497	$ 124,155		$ 122,059	$ 232,936	$ 122,059
Other comprehensive loss before reclassifications		2,252			(610)				1,132	(2,404)
Amounts reclassified from accumulated other comprehensive loss, net of tax		216			20				649	60
Total other comprehensive income (loss)		2,468	(6,003)	5,316	(590)	967		(2,721)	1,781	(2,344)
Reclassification of stranded tax benefits	[1]					0
Balance at end of period		324,195	295,434	272,131	202,518	158,497		124,155	324,195	202,518
Defined benefit pension items
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(23,385)		(23,818)	(8,341)			(6,048)	(23,818)	(6,048)
Other comprehensive loss before reclassifications		0			0				0	0
Amounts reclassified from accumulated other comprehensive loss, net of tax		216			20				649	60
Total other comprehensive income (loss)		216			20				649	60
Reclassification of stranded tax benefits										(2,333)
Balance at end of period		(23,169)	(23,385)		(8,321)	(8,341)			(23,169)	(8,321)
Currency translation adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(19,000)		(17,880)	(12,184)			(10,390)	(17,880)	(10,390)
Other comprehensive loss before reclassifications		2,252			(610)				1,132	(2,404)
Amounts reclassified from accumulated other comprehensive loss, net of tax		0			0				0	0
Total other comprehensive income (loss)		2,252			(610)				1,132	(2,404)
Reclassification of stranded tax benefits										0
Balance at end of period		(16,748)	(19,000)		(12,794)	(12,184)			(16,748)	(12,794)
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(42,385)	(36,382)	(41,698)	(20,525)	(19,159)		(16,438)	(41,698)	(16,438)
Total other comprehensive income (loss)		2,468	(6,003)	5,316	(590)	967		(2,721)
Reclassification of stranded tax benefits						(2,333)	[1]			(2,333)
Balance at end of period		$ (39,917)	$ (42,385)	$ (36,382)	$ (21,115)	$ (20,525)		$ (19,159)	$ (39,917)	$ (21,115)

[1] Due to the adoption of ASU 2018-02.