Cash, cash equivalents and short-term investments (Detail) (USD $) In Thousands, unless otherwise specified	Apr. 03, 2015	Jan. 02, 2015
Fair Value Measurements [Line Items]
Amortized Cost	$ 145,015	$ 154,380
Unrealized Gains	13	27
Unrealized Losses	(2)	(4)
Estimated Fair Value	145,026	154,403
Total short-term investments
Fair Value Measurements [Line Items]
Amortized Cost	21,357	24,890
Unrealized Gains	13	27
Unrealized Losses	(2)	(4)
Estimated Fair Value	21,368	24,913
Money market securities
Fair Value Measurements [Line Items]
Amortized Cost	48,940	45,478
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	48,940	45,478
Total cash and cash equivalents
Fair Value Measurements [Line Items]
Amortized Cost	123,658	129,490
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	123,658	129,490
Cash
Fair Value Measurements [Line Items]
Amortized Cost	74,718	84,012
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	74,718	84,012
Total cash equivalents
Fair Value Measurements [Line Items]
Amortized Cost	48,940	45,478
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	48,940	45,478
State and municipal bonds
Fair Value Measurements [Line Items]
Amortized Cost	21,357	24,890
Unrealized Gains	13	27
Unrealized Losses	(2)	(4)
Estimated Fair Value	$ 21,368	$ 24,913

Amount of accumulated gross unrealized gain on investments in available for sale securities.

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Amount of accumulated gross unrealized loss on investments in available for sale securities.

+ References

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- Definition

This item represents the fair value of cash, cash equivalents and short-term investments.

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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 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

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