Stock-Based Compensation (Schedule of Fair Value of the Restricted Stock Awards Granted During the Periods) (Details) - Restricted Stock [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019		Sep. 30, 2018
Time Vested [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0	0	999,957		888,810
Estimated fair value (in millions)	$ 0.0	$ 0.0	$ 15.5	[1]	$ 17.1	[1]
Time Vested [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0	0	927,173		844,498
Estimated fair value (in millions)	$ 0.0	$ 0.0	$ 14.6	[1]	$ 16.2	[1]
Percentage of shares granted expected to be distributed			95.00%		95.00%
Time Vested [Member] | Non-employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0	0	72,784		44,312
Estimated fair value (in millions)	$ 0.0	$ 0.0	$ 0.9	[1]	$ 0.9	[1]
Percentage of shares granted expected to be distributed			100.00%		100.00%
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0	0	424,070		362,070
Estimated fair value (in millions)	$ 0.0	$ 0.0	$ 7.1	[1]	$ 7.3	[1]
Performance Shares [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0	0	424,070		362,070
Estimated fair value (in millions)	$ 0.0	$ 0.0	$ 7.1	[1]	$ 7.3	[1]
Percentage of shares granted expected to be distributed			52.00%		74.00%
Performance Shares [Member] | Non-employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0	0	0		0
Estimated fair value (in millions)	$ 0.0	$ 0.0	$ 0.0	[1]	$ 0.0	[1]

[1] The performance shares represent 100% of the grant date fair value. (We recognize the grant date fair value minus estimated forfeitures.)