Earnings Per Common Share (Earnings per common share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income (loss)	$ 52,646	$ 59,186	$ (2,504)
Non-Convertible Preferred Stock Dividend (Series A,B and D)	(6,512)	(6,512)	(6,512)
Convertible Preferred Stock Dividend (Series C)	(7,350)	(7,350)	(7,350)
Income available to common shareholders	38,784	45,324	(16,366)
Effect of assumed conversion of convertible preferred stock	7,350	7,350	7,350
Income available to common sharesholders assuming conversion	$ 46,134	$ 52,674	$ (9,016)
Average common shares outstanding	43,939	43,913	44,231
Average potential common shares options	19	37	68
Average potential common shares convertible preferred stock	7,138	7,138	7,156
Average common shares outstanding and equivalents	51,096	51,088	51,455
Earnings per common share - basic	$ 0.88	$ 1.03	$ (0.37)
Earnings per common share - diluted	$ 0.88	$ 1.03	$ (0.37)