Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Option Activity) (Details) - Stock Options [Member] - $ / shares shares in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	1,229
Options granted, Number of shares	1,068
Options exercised, Number of shares	(63)
Options canceled, Number of shares	(6)
Options expired, Number of shares
Ending Balance, Number of shares	2,228	1,229
Exercisable, Number of shares	530
Beginning Balance, Weighted average exercise price per share	$ 3.82
Options granted, Weighted average exercise price per share	27.02
Options exercised, Weighted average exercise price per share	2.98
Options canceled, Weighted average exercise price per share	4.00
Options expired, Weighted average exercise price per share
Ending Balance, Weighted average exercise price per share	$ 14.97	$ 3.82
Weighted average remaining life	8 years 7 months 6 days	7 years 7 months 6 days