Stock-Based Compensation (Summary Of Stock Options) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Stock-Based Compensation [Abstract]
Number of Options, Outstanding, Beginning balance | shares	1,197
Number of Options, Exercised | shares	(502)
Number of Options, Forfeited or expired | shares	(14)
Number of Options, Outstanding, Ending balance | shares	681
Number of Options, Exercisable as of September 30, 2017 | shares	527
Weighted-Average Exercise Price, Outstanding, Beginning balance | $ / shares	$ 19.51
Weighted-Average Exercise Price, Exercised | $ / shares	19.56
Weighted-Average Exercise Price, Forfeited or expired | $ / shares	20.51
Weighted-Average Exercise Price, Outstanding, Ending balance | $ / shares	19.45
Weighted-Average Exercise Price, Exercisable as of September 30, 2017 | $ / shares	$ 18.39
Weighted-Average Remaining Contractual Term (Years), Outstanding	5 years 3 months 21 days
Weighted-Average Remaining Contractual Term (Years), Exercisable as of September 30, 2017	3 years 6 months 14 days
Aggregate Intrinsic Value, Outstanding as of September 30, 2017 | $	$ 10,015
Aggregate Intrinsic Value, Exercisable as of September 30, 2017 | $	$ 8,304