Stock-Based Compensation (Summary of Company's SARs Activity) (Details) - SARs [Member] - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance	307,323
Exercised	(5,803)
Ending balance	301,520	307,323
Exercisable	289,356
Outstanding, Weighted Average Exercise Price	$ 36.57
Exercised, Weighted Average Exercise Price	31.96
Outstanding, Weighted Average Exercise Price	36.66	$ 36.57
Exercisable, Weighted Average Exercise Price	$ 35.61
Outstanding, Average Remaining Contractual Term Years	5 years 5 months 27 days	5 years 11 months 27 days
Exercisable, Average Remaining Contractual Term Years	5 years 4 months 24 days
Outstanding, Aggregate Intrinsic Value	$ 4,577
Outstanding, Aggregate Intrinsic Value	4,536	$ 4,577
Exercisable, Aggregate Intrinsic Value	$ 4,657