Acquisitions (Details) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended		0 Months Ended			1 Months Ended
	Jan. 03, 2015	Dec. 29, 2012	Oct. 17, 2013	Jul. 01, 2013	Jul. 03, 2012	Sep. 30, 2012 item	Dec. 28, 2013
Acquisition
Earn-Out, fair value	$ 14,150,000						$ 12,919,000
Amount of initial consideration held in escrow by the company as security for breaches of representations and warranties and certain other expressly enumerated matters							20,010,000
Purchase price allocation
Goodwill	228,781,000	130,265,000					228,781,000
Weighted-Average Amortization Period	9 years
Net gain on purchase		(8,457,000)
Customer relationships
Purchase price allocation
Weighted-Average Amortization Period	9 years
Trademarks
Purchase price allocation
Weighted-Average Amortization Period	10 years
Energy Micro
Acquisition
Purchase price of acquisition				140,600,000
Initial consideration			107,400,000	107,400,000
Deferred consideration in the form of a promissory note, fair value				19,200,000
Restricted stock exchanged of promissory note in form of deferred consideration on acquisition				0.5
Mandatory period of creditor notice after which the deferred consideration in the form of a promissory note will be exchanged for the entity's restricted stock				2 months
Earn-Out, fair value				14,000,000
Additional consideration on acquisition			33,300,000	33,300,000
Minimum annual revenue growth for additional consideration (as a percent)				25.00%
Earn out period				5 years
Maximum annual Earn-Out payment				6,666,666
Minimum revenue in single fiscal year from Earn-Out products required to make the entire Earn-Out amount payable				400,000,000
Amount of initial consideration held in escrow by the company as security for breaches of representations and warranties and certain other expressly enumerated matters			20,300,000	20,300,000
Percentage of Earn-Out contingent on the continued employment of certain key employees				28.76%
Period of continued employment of key employees for calculating Earn-out portion following acquisition date				3 years
Purchase price allocation
Intangible assets				55,400,000
Cash and cash equivalents				919,000
Other current assets				6,486,000
Goodwill				98,515,000
Other non-current assets				3,117,000
Current liabilities				(8,000,000)
Non-current deferred tax liabilities, net				(6,288,000)
Long-term debt				(8,434,000)
Other non-current liabilities				(1,133,000)
Total purchase price				140,582,000
Acquisition-related costs recorded in selling, general and administrative expenses							2,400,000
Energy Micro | Core and developed technology
Purchase price allocation
Intangible assets				29,100,000
Weighted-Average Amortization Period				7 years
Energy Micro | Customer relationships
Purchase price allocation
Intangible assets				6,400,000
Weighted-Average Amortization Period				8 years
Energy Micro | Trademarks
Purchase price allocation
Intangible assets				1,300,000
Weighted-Average Amortization Period				8 years
Energy Micro | In-process research and development
Purchase price allocation
Intangible assets				18,600,000
Discount rate applicable to the cash flows (as a percent)	13.00%
Ember
Acquisition
Purchase price of acquisition					79,000,000
Estimated fair value					4,000,000
Purchase price allocation
Intangible assets					39,140,000
Cash and cash equivalents					3,115,000
Accounts receivable					1,928,000
Inventories					4,749,000
Other current assets					324,000
Goodwill					14,777,000
Deferred tax assets - non-current					16,449,000
Other non-current assets					1,776,000
Current liabilities					(3,287,000)
Total purchase price					78,971,000
Ember | Developed technology
Purchase price allocation
Intangible assets					17,800,000
Weighted-Average Amortization Period					11 years
Ember | Customer relationships
Purchase price allocation
Intangible assets					5,620,000
Weighted-Average Amortization Period					9 years
Ember | Trademarks
Purchase price allocation
Intangible assets					910,000
Weighted-Average Amortization Period					12 years
Ember | In-process research and development
Purchase price allocation
Intangible assets					14,810,000
Discount rate applicable to the cash flows (as a percent)	12.50%
Corporate Headquarters Buildings
Purchase price allocation
Total purchase price						94,350,000
Buildings						90,900,000
Leasehold interest in ground leases						23,840,000
Acquired unfavorable leases						(11,925,000)
Lease-related charges						(8,000)
Net gain on purchase						(8,457,000)
Useful life of building						40 years
Useful life of leasehold interest in ground leases						86 years
Number of leases for which purchase prices were fixed						2
400 WCC
Purchase price allocation
Purchase option price for buildings						44,300,000
200 WCC
Purchase price allocation
Purchase option price for buildings						$ 50,100,000