Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 27, 2019	Dec. 28, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 232,936	$ 122,059
Other comprehensive loss before reclassifications	5,109	(2,746)
Amounts reclassified from accumulated other comprehensive loss	207	25
Total other comprehensive income (loss)	5,316	(2,721)
Balance at end of period	272,131	124,155
Defined benefit pension items
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(23,818)	(6,048)
Other comprehensive loss before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive loss	207	25
Total other comprehensive income (loss)	207	25
Balance at end of period	(23,611)	(6,023)
Currency translation adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(17,880)	(10,390)
Other comprehensive loss before reclassifications	5,109	(2,746)
Amounts reclassified from accumulated other comprehensive loss	0	0
Total other comprehensive income (loss)	5,109	(2,746)
Balance at end of period	(12,771)	(13,136)
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	(41,698)	(16,438)
Total other comprehensive income (loss)	5,316	(2,721)
Balance at end of period	$ (36,382)	$ (19,159)