Stock-Based Compensation (Summary Of Stock Options) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) $ / shares shares
Stock-Based Compensation [Abstract]
Number of Options, Outstanding, Beginning balance | shares	1,197
Number of Options, Exercised | shares	(256)
Number of Options, Forfeited or expired | shares	(10)
Number of Options, Outstanding, Ending balance | shares	931
Number of Options, Exercisable as of March 31, 2017 | shares	771
Weighted-Average Exercise Price, Outstanding, Beginning balance | $ / shares	$ 19.51
Weighted-Average Exercise Price, Exercised | $ / shares	20.07
Weighted-Average Exercise Price, Forfeited or expired | $ / shares	19.78
Weighted-Average Exercise Price, Outstanding, Ending balance | $ / shares	19.35
Weighted-Average Exercise Price, Exercisable as of March 31, 2017 | $ / shares	$ 18.58
Weighted-Average Remaining Contractual Term (Years), Outstanding	5 years 5 months 26 days
Weighted-Average Remaining Contractual Term (Years), Exercisable as of March 31, 2017	3 years 8 months 26 days
Aggregate Intrinsic Value, Outstanding as of March 31, 2017 | $	$ 11,585
Aggregate Intrinsic Value, Exercisable as of March 31, 2017 | $	$ 10,195