Marketable Securities (Schedule of Available-for-sale Marketable Securities by Contractual Maturity Date) (Details) - USD ($) $ in Thousands	Mar. 30, 2019	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, amortized cost	$ 25,296	$ 25,792
Due in one year or less, fair value	25,238	25,670
Due after one year through three years, amortized cost	31,228	30,572
Due after one year through three years, fair value	31,177	30,281
Amortized cost	56,524	56,364
Fair value	$ 56,415	$ 55,951