Condensed Consolidated Statement of Shareholders' Equity - 3 months ended Mar. 31, 2016 - 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, 2015		2,000	24,649,044
Stockholders' Equity, Beginning Balance at Dec. 31, 2015	$ 596,566	$ 48,163	$ 271	$ 241,239	$ 355,427	$ (48,534)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,189				9,189
Dividends, Preferred Stock	(1,219)				(1,219)
Reversal of deferred tax asset related to stock options and executive deferred compensation distributions	(1,030)			(1,030)
Stock options exercised, shares			6,000
Stock options exercised	73			(46)		119
Stock-based compensation expense	916			916
Deferral of executive and director compensation	110			110
Executive and director deferred compensation distributions shares			10,661
Executive and director deferred compensation distributions	0			(212)		212
Shares Outstanding, Ending Balance at Mar. 31, 2016		2,000	24,665,705
Stockholders' Equity, Ending Balance at Mar. 31, 2016	$ 604,605	$ 48,163	$ 271	$ 240,977	$ 363,397	$ (48,203)