Common Stock (Vested Restricted Stock Aggregate Intrinsic Value And Grant Date Fair Value) (Details) - Restricted Stock - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares vested - aggregated intrinsic value	$ 3,711	$ 2,515	$ 3,451
Fair value at grant date	$ 2,803	$ 1,993	$ 3,327