Stock Option Plans (Summary of Grants Shares Issued and Fair Market Value) (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
March [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	6,675	4,670
Fair Market Value	$ 8.08	$ 8.35
June [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	6,723	3,552
Fair Market Value	$ 7.28	$ 9.85
July [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued		616
Fair Market Value		$ 9.85
September [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	7,459	4,741
Fair Market Value	$ 7.76	$ 9.05
December [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	6,210	5,192
Fair Market Value	$ 8.69	$ 8.27