Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 30, 2017	Dec. 31, 2016
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	$ 494,657	$ 153,961
Assets and liabilities measured at fair value on recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	159,662	69,432
Total short-term investments	94,575	12,416
Total assets at fair value	254,237	81,848
Assets and liabilities measured at fair value on recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	106,047	69,432
Assets and liabilities measured at fair value on recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1) | Government debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	53,615
Total short-term investments	94,575	12,416
Assets and liabilities measured at fair value on recurring basis | Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	12,684	11,057
Total short-term investments	400,082	141,545
Derivative instruments		1,808
Other assets, net		1,808
Total assets at fair value	412,766	154,410
Assets and liabilities measured at fair value on recurring basis | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	11,231	7,153
Total short-term investments	171,835	44,442
Assets and liabilities measured at fair value on recurring basis | Significant Other Observable Inputs (Level 2) | Government debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	1,453	3,904
Total short-term investments	228,247	97,103
Assets and liabilities measured at fair value on recurring basis | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities measured at fair value on a recurring basis
Other assets, net	5,681	5,196
Total assets at fair value	5,681	5,196
Assets and liabilities measured at fair value on recurring basis | Significant Unobservable Inputs (Level 3) | Auction rate securities
Financial assets and liabilities measured at fair value on a recurring basis
Total long-term investments	5,681	5,196
Assets and liabilities measured at fair value on recurring basis | Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	172,346	80,489
Total short-term investments	494,657	153,961
Derivative instruments		1,808
Other assets, net	5,681	7,004
Total assets at fair value	672,684	241,454
Assets and liabilities measured at fair value on recurring basis | Fair Value | Money market funds
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	106,047	69,432
Assets and liabilities measured at fair value on recurring basis | Fair Value | Corporate debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	11,231	7,153
Total short-term investments	171,835	44,442
Assets and liabilities measured at fair value on recurring basis | Fair Value | Government debt securities
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	55,068	3,904
Total short-term investments	322,822	109,519
Assets and liabilities measured at fair value on recurring basis | Fair Value | Auction rate securities
Financial assets and liabilities measured at fair value on a recurring basis
Total long-term investments	$ 5,681	$ 5,196