Equity Incentive Plans (Summary Of Exercisable Options) (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($) $ / shares shares
Options outstanding (in shares) | shares	113,879
Weighted avg. life remaining (in years)	4 years 6 months
Weighted avg. exercise price	$ 55.10
Aggregate intrinsic value | $	$ 2,221
Forty Four Point Sixty Two To Forty Nine Point Nine Nine [Member]
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	$ 44.62
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 49.99
Options outstanding (in shares) | shares	31,673
Weighted avg. life remaining (in years)	2 years 7 months 6 days
Fifty To Fifty Nine Point Nine Nine Member
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	$ 50.00
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 59.99
Options outstanding (in shares) | shares	29,392
Weighted avg. life remaining (in years)	4 years 7 months 6 days
Sixty To Sixty Five Point Five Zero Member
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	$ 60.00
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 69.99
Options outstanding (in shares) | shares	51,706
Weighted avg. life remaining (in years)	5 years 7 months 6 days
Seventy To Seventy Six Point Six Three [Member]
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	$ 70.00
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 76.63
Options outstanding (in shares) | shares	1,108
Weighted avg. life remaining (in years)	7 years 8 months 12 days