Basis of Presentation (Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share
Net income	$ 33,710	$ 21,632	$ 84,857	$ 61,600
Preferred dividends	(13)	(13)	(39)	(45)
Interest expense on convertible preferred debt	0	3	0	12
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 33,697	$ 21,622	$ 84,818	$ 61,567
Weighted average common shares outstanding for basic earnings per share (in shares)	34,452	29,648	32,520	27,569
Assumed incremental common shares issued upon non-vested restricted stock units (in shares)	192	262	187	265
Weighted average common shares for diluted earnings per share (in shares)	34,644	29,910	32,707	27,834
Earnings per common share — basic (in dollars per share)	$ 0.98	$ 0.73	$ 2.61	$ 2.23
Earnings per common share — diluted (in dollars per share)	$ 0.97	$ 0.72	$ 2.59	$ 2.21
Number of antidilutive common stock equivalents excluded from diluted earnings per share computation (in shares)	0	0	0	0