Share-Based Compensation (Summary Of Stock Option Activity) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding Shares, Beginning balance | shares	85,500
Granted, Shares | shares	0
Exercised, Shares | shares	(43,000)
Cancelled or expired, Shares | shares	0
Outstanding Shares, Ending balance | shares	42,500
Exercisable, Shares | shares	42,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Outstanding, Weighted-Average Exercise Price, Beginning balance (in dollars per share) | $ / shares	$ 47.52
Granted, Weighted-Average Exercise Price (in dollars per share) | $ / shares	0.00
Exercised, Weighted-Average Exercise Price (in dollars per share) | $ / shares	50.28
Canceled or Expired, Weighted-Average Exercise Price (in dollars per share) | $ / shares	0.00
Outstanding, Weighted-Average Exercise Price, Ending balance (in dollars per share) | $ / shares	44.72
Exercisable, Weighted-Average Exercise Price (in dollars per share) | $ / shares	$ 44.72
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding, Weighted-Average Remaining Contractual Term (Years)	3 years
Exercisable, Weighted-Average Remaining Contractual Term (Years)	3 years
Outstanding, Aggregate Intrinsic Value | $	$ 371
Exercisable, Aggregate Intrinsic Value | $	$ 371