Share-Based Compensation - Performance Thresholds (Details)	Dec. 31, 2020	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Market performance percentage, maximum	200.00%
Market performance percentage, target	100.00%
Market performance percentage, minimum	50.00%
Market-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RMS relative market performance, high level	75.00%
RMS relative market performance, target level	55.00%
RMS relative market performance, threshold level	30.00%
RMS relative market performance, below threshold	30.00%
TSR, maximum	12.00%	12.00%
TSR, target	10.00%	10.00%
TSR, minimum	8.00%	8.00%
Market performance percentage, maximum	150.00%	150.00%
Market performance percentage, target	100.00%	100.00%
Market performance percentage, minimum	50.00%	50.00%
Market performance percentage, below threshold	0.00%