FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 30, 2017	Jul. 01, 2017	Dec. 31, 2016	Jul. 02, 2016
Short-term Investments [Abstract]
Cash held in bank accounts	$ 157,153	$ 219,270	$ 222,796	$ 95,929
Money market funds
Short-term Investments [Abstract]
Cash held in bank accounts	63,202	99,037
Commercial paper
Short-term Investments [Abstract]
Cash held in bank accounts	3,996	22,981
Cash-in-bank
Short-term Investments [Abstract]
Cash held in bank accounts	85,938	79,259
Fair Value, Measurements, Recurring
Short-term Investments [Abstract]
Total assets measured at fair value	204,170	178,282
Fair Value, Measurements, Recurring | Commercial paper
Short-term Investments [Abstract]
Short-term investments	66,582	23,459
Fair Value, Measurements, Recurring | US Treasury securities
Short-term Investments [Abstract]
Short-term investments	47,831	4,006
Fair Value, Measurements, Recurring | Corporate bonds
Short-term Investments [Abstract]
Short-term investments	18,542	10,094
Fair Value, Measurements, Recurring | Money market funds
Cash and cash equivalents:
Cash and cash equivalents	63,202	99,037
Restricted cash:
Restricted cash		712
Fair Value, Measurements, Recurring | Commercial paper
Cash and cash equivalents:
Cash and cash equivalents	3,996	22,981
Fair Value, Measurements, Recurring | U.S. agency securities
Cash and cash equivalents:
Cash and cash equivalents		15,981
Fair Value, Measurements, Recurring | Corporate bonds
Cash and cash equivalents:
Cash and cash equivalents	4,017	2,012
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Short-term Investments [Abstract]
Total assets measured at fair value	63,202	99,749
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Cash and cash equivalents:
Cash and cash equivalents	63,202	99,037
Restricted cash:
Restricted cash		712
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Short-term Investments [Abstract]
Total assets measured at fair value	140,968	78,533
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commercial paper
Short-term Investments [Abstract]
Short-term investments	66,582	23,459
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | US Treasury securities
Short-term Investments [Abstract]
Short-term investments	47,831	4,006
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate bonds
Short-term Investments [Abstract]
Short-term investments	18,542	10,094
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commercial paper
Cash and cash equivalents:
Cash and cash equivalents	3,996	22,981
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. agency securities
Cash and cash equivalents:
Cash and cash equivalents		15,981
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate bonds
Cash and cash equivalents:
Cash and cash equivalents	$ 4,017	$ 2,012