XML 18 R37.htm IDEA: XBRL DOCUMENT v3.19.3
Balance Sheet Details - Net Gain on Equity Method Securities (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]          
Net gains and losses recognized during the period on equity securities $ 0.0 $ 34.9 $ (4.2) $ 85.0  
Less: Net gains and losses recognized during the period on equity securities sold during the period 0.0 (14.1) 4.2 (44.2)  
Unrealized gains recognized during the reporting period on equity securities still held at the reporting date $ 0.0 $ 20.8 $ 0.0 $ 40.8  
Contractual maturities of debt securities (less than) 12 months   12 months   12 months