Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	3 Months Ended
Apr. 02, 2016	Jan. 02, 2016
Available-for-sale securities
Available-for-sale securities, Cost	$ 185,285
Cash, cash equivalents and investments
Auction-rate securities guaranteed by the U.S. government	6,000
Auction-rate securities privately insured	2,000
Auction-rate securities having credit rating 'AA'	6,000
Auction-rate securities having credit rating 'A'	2,000
Other-than-temporary impairment losses	0
Cash on hand, Cost	76,197	$ 59,071
Cash on hand, Fair Value	76,197	59,071
Cash and cash equivalents, Cost	126,690	114,084
Cash and cash equivalents, Gross Unrealized Gains		1
Cash and cash equivalents, Fair Value	126,690	114,085
Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	50,493	55,013
Available-for-sale securities, Gross Unrealized Gains		1
Available-for-sale securities, Fair Value	50,493	55,014
Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	126,792	128,900
Available-for-sale securities, Gross Unrealized Losses	(32)	(42)
Available-for-sale securities, Gross Unrealized Gains	64	43
Available-for-sale securities, Fair Value	126,824	128,901
Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	8,000	8,000
Available-for-sale securities, Gross Unrealized Losses	(1,155)	(874)
Available-for-sale securities, Fair Value	6,845	7,126
Money market funds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	40,720	37,721
Available-for-sale securities, Fair Value	40,720	37,721
Municipal bonds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	5,724	1,576
Available-for-sale securities, Gross Unrealized Gains		1
Available-for-sale securities, Fair Value	5,724	1,577
Municipal bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	85,668	93,506
Available-for-sale securities, Gross Unrealized Losses	(14)	(32)
Available-for-sale securities, Gross Unrealized Gains	55	42
Available-for-sale securities, Fair Value	85,709	93,516
Commercial paper \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	1,200	11,272
Available-for-sale securities, Fair Value	1,200	11,272
Commercial paper \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	2,489	11,176
Available-for-sale securities, Fair Value	2,489	11,176
Variable-rate demand notes \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	18,395	8,995
Available-for-sale securities, Fair Value	18,395	8,995
Certificates of deposit \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	2,849	2,845
Available-for-sale securities, Fair Value	2,849	2,845
Certificates of deposit \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost		8,000
Available-for-sale securities, Fair Value		8,000
US government agency \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost		1,599
Available-for-sale securities, Fair Value		1,599
US government agency \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost		3,997
Available-for-sale securities, Gross Unrealized Gains		1
Available-for-sale securities, Fair Value		3,998
International government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	2,220	2,227
Available-for-sale securities, Gross Unrealized Losses		(7)
Available-for-sale securities, Gross Unrealized Gains	1
Available-for-sale securities, Fair Value	2,221	2,220
Corporate bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	8,021	999
Available-for-sale securities, Gross Unrealized Losses	(18)	(3)
Available-for-sale securities, Fair Value	8,003	996
U.S. government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	6,004
Available-for-sale securities, Gross Unrealized Gains	5
Available-for-sale securities, Fair Value	6,009
Asset-backed securities \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	3,995
Available-for-sale securities, Gross Unrealized Gains	3
Available-for-sale securities, Fair Value	3,998
Auction rate securities \| Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	8,000	8,000
Available-for-sale securities, Gross Unrealized Losses	(1,155)	(874)
Available-for-sale securities, Fair Value	$ 6,845	$ 7,126

This element represents the amount of auction-rate securities that is guaranteed by the U.S. government.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

This element represents the amount of auction-rate securities having credit rating of 'A'.

+ References

No definition available.

+ Details

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- Definition

This element represents the amount of auction-rate securities having credit rating of 'AA'.

+ References

No definition available.

+ Details

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- Definition

This element represents the amount of auction-rate securities that is privately insured.

+ References

No definition available.

+ Details

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- Definition

This element represents the adjusted cost of cash and cash equivalents that are considered available-for-sale and recorded at fair value.

+ References

No definition available.

+ Details

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- Definition

This element represents the unrealized gains from cash and cash equivalents.

+ References

No definition available.

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- Definition

Represents fair value of cash which is similar to carrying value of cash as of balance sheet date.

+ References

No definition available.

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- Definition

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6506951

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6507016

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No definition available.

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- Definition

The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

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-Name Accounting Standards Codification
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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