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Line of Credit Narrative (Details 2) - USD ($)
$ in Millions
Sep. 30, 2020
Dec. 31, 2019
Oct. 12, 2017
Debt Disclosure [Abstract]      
Current borrowing capacity for line of credit facility     $ 750
Maximum borrowing capacity for line of credit facility     $ 1,000
Line of credit borrowings outstanding $ 0 $ 0  
Outstanding letters of credit issued against line of credit facility $ 1 $ 1