Stock-Based Compensation (Summary Of Stock Options) (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Stock-Based Compensation [Abstract]
Number of Options, Outstanding, Beginning balance | shares	1,197
Number of Options, Exercised | shares	(411)
Number of Options, Forfeited or expired | shares	(11)
Number of Options, Outstanding, Ending balance | shares	775
Number of Options, Exercisable as of June 30, 2017 | shares	619
Weighted-Average Exercise Price, Outstanding, Beginning balance | $ / shares	$ 19.51
Weighted-Average Exercise Price, Exercised | $ / shares	19.71
Weighted-Average Exercise Price, Forfeited or expired | $ / shares	19.99
Weighted-Average Exercise Price, Outstanding, Ending balance | $ / shares	19.4
Weighted-Average Exercise Price, Exercisable as of June 30, 2017 | $ / shares	$ 18.46
Weighted-Average Remaining Contractual Term (Years), Outstanding	5 years 4 months 6 days
Weighted-Average Remaining Contractual Term (Years), Exercisable as of June 30, 2017	3 years 7 months 20 days
Aggregate Intrinsic Value, Outstanding as of June 30, 2017 | $	$ 10,004
Aggregate Intrinsic Value, Exercisable as of June 30, 2017 | $	$ 8,559