Fair Value Measurements (Details) $ in Thousands	Sep. 26, 2015 USD ($)	[1]
Level 1 [Member]
Fair value measurement
Total
Level 1 [Member] | Time deposits [Member]
Fair value measurement
Total
Level 1 [Member] | Repurchase Agreements [Member]
Fair value measurement
Total
Level 1 [Member] | National government and agency securities [Member]
Fair value measurement
Total
Level 1 [Member] | State and municipal bond obligations [Member]
Fair value measurement
Total
Level 1 [Member] | Corporate bonds and notes [Member]
Fair value measurement
Total
Level 1 [Member] | Asset backed securities [Member]
Fair value measurement
Total
Level 1 [Member] | Mortgage backed securities [Member]
Fair value measurement
Total
Level 2 [Member]
Fair value measurement
Total	$ 100,510
Level 2 [Member] | Time deposits [Member]
Fair value measurement
Total	40,062
Level 2 [Member] | Repurchase Agreements [Member]
Fair value measurement
Total	754
Level 2 [Member] | National government and agency securities [Member]
Fair value measurement
Total	3,241
Level 2 [Member] | State and municipal bond obligations [Member]
Fair value measurement
Total	5,242
Level 2 [Member] | Corporate bonds and notes [Member]
Fair value measurement
Total	39,188
Level 2 [Member] | Asset backed securities [Member]
Fair value measurement
Total	7,619
Level 2 [Member] | Mortgage backed securities [Member]
Fair value measurement
Total	$ 4,404
Level 3 [Member]
Fair value measurement
Total
Level 3 [Member] | Time deposits [Member]
Fair value measurement
Total
Level 3 [Member] | Repurchase Agreements [Member]
Fair value measurement
Total
Level 3 [Member] | National government and agency securities [Member]
Fair value measurement
Total
Level 3 [Member] | State and municipal bond obligations [Member]
Fair value measurement
Total
Level 3 [Member] | Corporate bonds and notes [Member]
Fair value measurement
Total
Level 3 [Member] | Asset backed securities [Member]
Fair value measurement
Total
Level 3 [Member] | Mortgage backed securities [Member]
Fair value measurement
Total
Fair Value [Member]
Fair value measurement
Total	$ 100,510
Fair Value [Member] | Time deposits [Member]
Fair value measurement
Total	40,062
Fair Value [Member] | Repurchase Agreements [Member]
Fair value measurement
Total	754
Fair Value [Member] | National government and agency securities [Member]
Fair value measurement
Total	3,241
Fair Value [Member] | State and municipal bond obligations [Member]
Fair value measurement
Total	5,242
Fair Value [Member] | Corporate bonds and notes [Member]
Fair value measurement
Total	39,188
Fair Value [Member] | Asset backed securities [Member]
Fair value measurement
Total	7,619
Fair Value [Member] | Mortgage backed securities [Member]
Fair value measurement
Total	$ 4,404

[1] $20,798,000 of the time deposits and $754,000 of the repurchase agreements are included in cash and cash equivalents; the balance of the investments are included in short-term investments in marketable securities on our consolidated balance sheet.