Stock-Based Compensation (Summary of Company's SARs Activity) (Details) - SARs [Member] - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance	307,323
Exercised	(32,391)
Ending balance	274,932	307,323
Exercisable	262,768
Outstanding, Weighted Average Exercise Price	$ 36.57
Exercised, Weighted Average Exercise Price	33.48
Outstanding, Weighted Average Exercise Price	36.93	$ 36.57
Exercisable, Weighted Average Exercise Price	$ 35.79
Outstanding, Average Remaining Contractual Term Years	5 years 3 months 7 days	5 years 11 months 27 days
Exercisable, Average Remaining Contractual Term Years	5 years 2 months 1 day
Outstanding, Aggregate Intrinsic Value	$ 4,577
Outstanding, Aggregate Intrinsic Value	5,421	$ 4,577
Exercisable, Aggregate Intrinsic Value	$ 5,482