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Employee Benefit Plans (Defined Contribution Plan) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Employee Savings Plan [Member]      
Defined Contribution Plan Disclosure [Line Items]      
Employer contributions $ 9.1 $ 8.3 $ 7.5