Earnings per Share (EPS) and Common Stock (Earnings per Share Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Mar. 30, 2019	Mar. 31, 2018
Earnings Per Share and Common Stock
Net income (loss)	$ (43,513)	$ 7,922	$ (22,528)	$ 21,799
Weighted average shares outstanding—Basic (in shares)	118,461	116,241	118,392	115,986
Dilutive effect of employee stock options, restricted shares and restricted stock units (in shares)	0	1,664	0	1,794
Weighted average shares outstanding—Diluted (in shares)	118,461	117,905	118,392	117,780
Earnings per share—Basic (in USD per share)	$ (0.37)	$ 0.07	$ (0.19)	$ 0.19
Earnings per share—Diluted (in USD per share)	$ (0.37)	$ 0.07	$ (0.19)	$ 0.19