XML 155 R140.htm IDEA: XBRL DOCUMENT v3.20.4
Fair Value Measurements (Details) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Quoted Prices in Active Markets for Identical Assets (Level 2) [Member] | Senior Unsecured Notes [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Senior unsecured notes $ 971.6 $ 356.8