Basis of Presentation (Earnings per share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share
Net income	$ 21,958	$ 20,970	$ 39,968	$ 40,979
Preferred dividends	(13)	(52)	(32)	(220)
Interest expense on convertible preferred debt	4	31	9	31
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 21,949	$ 20,949	$ 39,945	$ 40,790
Weighted average common shares outstanding for basic earnings per share (in shares)	26,687	24,524	26,512	24,093
Assumed incremental common shares issued upon exercise of stock options and non-vested restricted stock units (in shares)	286	451	286	448
Weighted average common shares for diluted earnings per share (shares)	26,973	24,975	26,798	24,541
Earnings per common share — basic (in dollars per share)	$ 0.82	$ 0.85	$ 1.51	$ 1.69
Earnings per common share — diluted (in dollars per share)	$ 0.81	$ 0.84	$ 1.49	$ 1.66
Number of antidilutive common stock equivalents excluded from diluted earnings per share computation (in shares)	0	0	0	0