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Balance Sheet Components (Narrative) (Details)
12 Months Ended
Dec. 31, 2018
USD ($)
segment
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Balance Sheet Related Disclosures [Abstract]      
Equity securities without readily determinable fair values $ 2,900,000 $ 4,500,000  
Gain (impairment charges) related to long-term investment 1,400,000 0 $ 0
Upward adjustments for observable price changes 200,000    
Amortization expense 8,300,000 11,000,000 15,700,000
Intangible assets impairment charges $ 0 0 0
Number of reportable segments | segment 2    
Number of operating segments | segment 2    
Goodwill impairment charges $ 0 0 $ 0
Accumulated goodwill impairment charges $ 74,200,000 $ 74,200,000