Stock Transactions And Stock-Based Compensation (Key Terms of Shares) (Details) - Preferred stock - $ / shares		1 Months Ended	12 Months Ended
	Mar. 01, 2019	May 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Series A Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, dividend rate, percentage	4.75%		4.75%	4.75%
Preferred stock, liquidation preference per share	$ 1,000		$ 1,000
Series A Preferred Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Convertible preferred stock, shares issued upon conversion			6.6563
Series A Preferred Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Convertible preferred stock, shares issued upon conversion			8.1538
Series B Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, dividend rate, percentage		5.00%	5.00%
Preferred stock, liquidation preference per share		$ 1,000	$ 1,000
Series B Preferred Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Convertible preferred stock, shares issued upon conversion			5.0081
Series B Preferred Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Convertible preferred stock, shares issued upon conversion			6.1349