Significant Accounting Policies - Earnings Per Share (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Sep. 29, 2018	Sep. 30, 2017	Oct. 01, 2016
Earnings Per Share [Abstract]
Weighted average shares outstanding—basic (shares)									24,572,000	24,487,000	24,142,000
Dilutive effect of employee stock awards (shares)									279,000	290,000	273,000
Weighted average shares outstanding—diluted (shares)									24,851,000	24,777,000	24,415,000
Net income from continuing operations									$ 247,360	$ 208,644	$ 87,502
Loss from discontinued operations, net of income taxes									(2)	(1,522)	0
Net income	$ 73,185	$ 66,970	$ 65,302	$ 41,901	$ 73,752	$ 61,117	$ 41,845	$ 30,408	$ 247,358	$ 207,122	$ 87,502
Dilutive securities excluded from calculation of dilutive shares (shares)									103,547	505	323