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Share-Based Compensation (PBRSU Weighted Average Assumptions) (Details) - PBRSUs
6 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected dividend yield (1) 0.00% 0.00%
Risk-free interest rate 0.60% 2.44%
Expected volatility 32.53% 28.24%
Average total stockholder return (21.47%) 17.15%