Stockholders' Equity (Shares repurchased under the stock repurchase program) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Value		$ 104,502	$ 104,860
April 2015 [Member]
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased as part of the stock repurchase program (Shares)	204,338
Treasury Stock Acquired, Average Cost Per Share	$ 14.38
Treasury Stock, Value	$ 2,939
May 2015 [Member]
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased as part of the stock repurchase program (Shares)	48,200
Treasury Stock Acquired, Average Cost Per Share	$ 13.09
Treasury Stock, Value	$ 631
June 2015 [Member]
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased as part of the stock repurchase program (Shares)	51,447
Treasury Stock Acquired, Average Cost Per Share	$ 12.81
Treasury Stock, Value	$ 659
July 2015 [Member]
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased as part of the stock repurchase program (Shares)	500,000
Treasury Stock Acquired, Average Cost Per Share	$ 9.39
Treasury Stock, Value	$ 4,696
Seventy Millions Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Common shares repurchased as part of the stock repurchase program (Shares)	803,985
Treasury Stock Acquired, Average Cost Per Share	$ 11.1
Treasury Stock, Value	$ 8,925