Share-Based Compensation (Weighted Average Assumptions) (Details) - $ / shares		3 Months Ended		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price	[1]	$ 10.02				$ 29.04			$ 41.97
Expected volatility (b)	[2]	38.30%	34.00%						34.00%
Risk-free interest rate (c)	[3]	0.40%	2.42%						2.37%
Expected term in years (e)	[4]	3 years	3 years						3 years
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Exercise Price	[5]			$ 0		$ 5.64		$ 9.07
Expected volatility (b)	[6]			0.00%		32.50%		32.50%
Risk-free interest rate (c)	[7]			0.00%		2.50%		2.70%
Expected dividend yield	[8]							2.00%
Expected term in years (e)	[9]			0 years		6 years 6 months		6 years 6 months
Minimum | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield				0.00%	[8]	2.60%	[8]		2.00%

[1] The weighted-average fair value was based on performance share units granted during the period.

[2] Expected volatility is based on normalized historical volatility of our shares over a preceding period commensurate with the expected term of the performance share units.

[3] he risk-free rate for the expected term of the performance share units is based on the U.S. Treasury yield curve in effect at the time of grant.

[4] For awards subject to service-based vesting, due to the lack of historical exercise and post-vesting termination patterns of the post-Merger employee base, the expected term was estimated using a simplified method for all awards granted in 2020, 2019 and 2018.

[5] The weighted-average fair value was based on stock options granted during the period.

[6] Expected volatility is based on normalized historical volatility of our shares over a preceding period commensurate with the expected term of the option.

[7] e risk-free rate for the expected term of the option is based on the U.S. Treasury yield curve in effect at the time of grant.

[8] hare options awarded in 2020. Share options awarded in 2019 and 2018 were valued using an expected dividend yield of 2.6% and 2.0%, respectively.

[9] For awards subject to service-based vesting, due to the lack of historical exercise and post-vesting termination patterns of the post-Merger employee base, the expected term was estimated using a simplified method for all awards granted in 2020, 2019 and 2018.