v3.8.0.1
Organization and Summary of Significant Accounting Policies - Narrative - Derivatives (Details) - USD ($)
$ in Millions
Dec. 31, 2017
Jan. 01, 2017
Foreign exchange forward [Member] | Not designated as hedging instrument [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Notional amount of outstanding forward contracts $ 88 $ 69