Stock-Based Compensation (Summary Of Stock Options Under The 2007 Plan) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Shares
Options outstanding at beginning of year (in shares)	169,000
Granted (in shares)	0
Exercised (in shares)	(78,000)
Forfeited and expired (in share)	0
Options outstanding at end of year (in shares)	91,000	169,000
Vested and expected to vest at end of year, (in shares)	91,000
Exercisable at end of year (in shares)	90,000
Weighted average exercise price
Options outstanding at the end of year (usd per share)	$ 63.84	$ 61.73
Options granted during the year (usd per share)	0.00
Options exercised during the year (usd per share)	59.24
Forfeited and expired (usd per share)	0.00
Vested and expected to vest, weighted average exercise price (usd per share)	63.84
Exercisable, weighted average exercise price (usd per share)	$ 63.82
Additional Disclosures
Weighted average remaining life	4 years 10 months 17 days
Vested and expected to vest, weighted average remaining contractual term (years)	4 years 10 months 17 days
Exercisable, weighted average remaining contractual term (years)	4 years 10 months 17 days
Options outstanding at end of year, aggregate intrinsic value	$ 12,360
Vested and expected to vest, aggregate intrinsic value	12,360
Exercisable, aggregate intrinsic value	$ 12,227