Stock Based Compensation (Additional Information Regarding Stock Award Activity) (Details) - Stock Awards [Member] - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-Average Grant Date Fair Value of Shares Granted During the Period (per share)		$ 19.96	$ 17.59	$ 19.96	$ 17.59
Total Grant Date Fair Value of Shares Vested During the Period		$ 4,319	$ 3,727	$ 4,659	$ 4,073
Share-based Liability Awards Paid During the Period	[1]	$ 0	$ 0	$ 1,127	$ 0

[1] Amount reflects the issuance of performance share awards related to the 2013-15 Performance Share Plan during the period.