Condensed Consolidated Statement of Shareholders' Equity - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Total	Preferred Shares [Member]	Common Shares [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Shares [Member]
Shares Outstanding, Beginning Balance at Dec. 31, 2014		2,000	24,512,910
Stockholders' Equity, Beginning Balance at Dec. 31, 2014	$ 544,295	$ 48,163	$ 271	$ 238,560	$ 308,539	$ (51,238)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	38,488				38,488
Dividends, Preferred Stock	(3,656)				(3,656)
Stock options exercised, shares			72,640
Stock options exercised	1,035			(408)		1,443
Stock-based compensation expense	3,073			3,073
Deferral of executive and director compensation	103			103
Executive and director deferred compensation distributions shares			63,314
Executive and director deferred compensation distributions	0			(1,257)		1,257
Shares Outstanding, Ending Balance at Sep. 30, 2015		2,000	24,648,864
Stockholders' Equity, Ending Balance at Sep. 30, 2015	$ 583,338	$ 48,163	$ 271	$ 240,071	$ 343,371	$ (48,538)