Convertible Preferred Stock And Stockholders' Equity (Summary Of Options And Stock Appreciation Rights Outstanding By Range Of Exercise Price) (Details) - Stock Options And Stock Appreciation Rights [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding	413,301	671,887
Weighted Average Remaining Life	6 years 26 days
Weighted Average Exercise Price	$ 9.04	$ 8.77
Number of Options Currently Exercisable	339,002
Weighted Average Exercise Price per Vested Share	$ 10.56
$0.00 - $2.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Price, Lower Limit	0.00
Range of Exercise Price, Upper Limit	$ 2.00
Options Outstanding	63,500
Weighted Average Remaining Life	7 years 5 months 5 days
Weighted Average Exercise Price	$ 1.66
Number of Options Currently Exercisable	38,362
Weighted Average Exercise Price per Vested Share	$ 1.86
$2.01 - $4.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Price, Lower Limit	2.01
Range of Exercise Price, Upper Limit	$ 4.00
Options Outstanding	154,001
Weighted Average Remaining Life	7 years 1 month 10 days
Weighted Average Exercise Price	$ 2.15
Number of Options Currently Exercisable	111,974
Weighted Average Exercise Price per Vested Share	$ 2.15
$4.01 - $10.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Price, Lower Limit	4.01
Range of Exercise Price, Upper Limit	$ 10.00
Options Outstanding	126,055
Weighted Average Remaining Life	6 years 2 months 27 days
Weighted Average Exercise Price	$ 4.04
Number of Options Currently Exercisable	118,921
Weighted Average Exercise Price per Vested Share	$ 4.04
$30.01 - $40.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Price, Lower Limit	30.01
Range of Exercise Price, Upper Limit	$ 40.00
Options Outstanding	45,245
Weighted Average Remaining Life	2 years 11 months 27 days
Weighted Average Exercise Price	$ 34.89
Number of Options Currently Exercisable	45,245
Weighted Average Exercise Price per Vested Share	$ 34.89
$40.01 - $50.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Price, Lower Limit	40.01
Range of Exercise Price, Upper Limit	$ 50.00
Options Outstanding	12,250
Weighted Average Remaining Life	1 year 5 months 9 days
Weighted Average Exercise Price	$ 43.90
Number of Options Currently Exercisable	12,250
Weighted Average Exercise Price per Vested Share	$ 43.90
$50.01 - $60.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Price, Lower Limit	50.01
Range of Exercise Price, Upper Limit	$ 60.00
Options Outstanding	12,250
Weighted Average Remaining Life	4 months 28 days
Weighted Average Exercise Price	$ 54.90
Number of Options Currently Exercisable	12,250
Weighted Average Exercise Price per Vested Share	$ 54.90