Stockholders' Equity (Schedule of Stock-Based Compensation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	$ 15,420	$ 14,043	$ 10,817
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	444	974	1,412
Deferred Stock Unit
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	7,830	7,023	4,343
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	1,770	1,031	910
Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	$ 5,376	$ 5,015	$ 4,152