Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	$ 451,114	$ 153,961
Total long-term investments	5,379	5,196
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	78,006	69,432
Total short-term investments	60,769	12,416
Total assets at fair value	138,775	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	78,006	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 short-term investments	60,769	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	33,323	11,057
Total short-term investments	390,345	141,545
Derivative instruments		1,808
Other assets, net		1,808
Total assets at fair value	423,668	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	31,827	7,153
Total short-term investments	175,259	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	1,496	3,904
Total short-term investments	215,086	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
Total long-term investments	5,379	5,196
Total assets at fair value	5,379	5,196
Contingent consideration, noncurrent	3,993
Total liabilities at fair value	3,993
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	5,379	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	111,329	80,489
Total short-term investments	451,114	153,961
Total long-term investments	5,379	5,196
Derivative instruments		1,808
Other assets, net		1,808
Total assets at fair value	567,822	241,454
Contingent consideration, noncurrent	3,993
Total liabilities at fair value	3,993
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	78,006	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	31,827	7,153
Total short-term investments	175,259	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	1,496	3,904
Total short-term investments	275,855	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	$ 5,379	$ 5,196