Stock-Based Compensation Plan (Summary Of Stock Option Activities) (Details) - Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding at beginning of period, Number of Shares	1,189,255	1,420,749	1,263,485
Options granted, Number of Shares	245,000	183,000	170,000
Options exercised, Number of Shares	(6,000)	(414,494)	(7,319)
Options forfeited/cancelled, Number of Shares			(5,417)
Options outstanding at end of period, Number of Shares	1,428,255	1,189,255	1,420,749
Options exercisable, Number of Shares	1,051,969
Expected to vest after end of period, Number of Shares	376,286
Options outstanding at beginning of period, Weighted Average Exercise Price	$ 18.08	$ 15.67	$ 14.84
Options granted, Weighted Average Exercise Price	7.87	21.72	22.09
Options exercised, Weighted Average Exercise Price	21.99	11.45	15.60
Options forfeited/cancelled, Weighted Average Exercise Price			22.55
Options outstanding at end of period, Weighted Average Exercise Price	16.31	$ 18.08	$ 15.67
Options exercisable, Weighted Average Exercise Price	17.56
Expected to vest after end of period, Weighted Average Exercise Price	$ 12.80
Weighted average remaining term	5 years 8 months 12 days
Weighted average remaining term	4 years 6 months
Expected to vest after end of period, Weighted Average Remaining Contractual Term (in years)	8 years 10 months 24 days
Aggregate intrinsic value of options outstanding	$ 896
Aggregate intrinsic value of options exercised	700
Expected to vest after end of period, Aggregate Intrinsic Value (in thousands)	$ 196