Stock-Based Compensation Plan (Summary Of Stock Option Activities) (Details) - Stock Options [Member] - $ / shares	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
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
Options granted, Number of Shares	245,000	177,000
Options exercised, Number of Shares		(396,994)
Options forfeited/cancelled, Number of Shares	(6,000)
Options outstanding at end of period, Number of Shares	1,428,255	1,200,755
Options exercisable, Number of Shares	1,013,680	885,855
Options outstanding at beginning of period, Weighted Average Exercise Price	$ 18.08	$ 15.67
Options granted, Weighted Average Exercise Price	7.87	21.89
Options exercised, Weighted Average Exercise Price		11.70
Options forfeited/cancelled, Weighted Average Exercise Price	21.99
Options outstanding at end of period, Weighted Average Exercise Price	16.31	17.90
Options exercisable, Weighted Average Exercise Price	$ 17.38	$ 16.45
Weighted average remaining term	4 years 10 months 24 days	5 years 3 months 18 days