Consolidated Statement of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Preferred Shares [Member]	Common Shares [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Shares [Member]
Stockholders' Equity, Beginning Balance at Dec. 31, 2011	$ 273,350	$ 96,325	$ 221	$ 139,943	$ 103,701	$ (66,840)
Shares Outstanding, Beginning Balance at Dec. 31, 2011		4,000	18,736,357
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	13,347				13,347
Common share issuance - shares			2,530,000
Net proceeds from issuance of common shares	42,085		25	42,060
Stock options exercised, shares			378,674
Stock options exercised - value	4,762			(2,759)		7,521
Stock-based compensation expense	1,734			1,734
Deferral of executive and director compensation	150			150
Executive and director deferred compensation distributions shares			42,222
Executive and director deferred compensation distributions	0			(839)		839
Stockholders' Equity, Ending Balance at Dec. 31, 2012	335,428	96,325	246	180,289	117,048	(58,480)
Shares Outstanding, Ending Balance at Dec. 31, 2012		4,000	21,687,253
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	151,423				151,423
Fair value over carrying value of preferred share redeemed	0	2,190			(2,190)
Dividends paid to preferred shareholders	(3,656)				(3,656)
Common share issuance - shares			2,461,000
Net proceeds from issuance of common shares	54,617		25	54,592
Preferred shares redeemed - shares		(2,000)
Preferred share redeemed - value	(50,352)	(50,352)
Stock options exercised, shares			184,832
Stock options exercised - value	2,640			(1,031)		3,671
Stock-based compensation expense	2,344			2,344
Deferral of executive and director compensation	359			359
Executive and director deferred compensation distributions shares			24,858
Executive and director deferred compensation distributions	0			(493)		493
Stockholders' Equity, Ending Balance at Dec. 31, 2013	492,803	48,163	271	236,060	262,625	(54,316)
Shares Outstanding, Ending Balance at Dec. 31, 2013		2,000	24,357,943
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	50,789				50,789
Dividends paid to preferred shareholders	(4,875)				(4,875)
Net proceeds from issuance of common shares	0
Stock options exercised, shares	(147,619)		147,619
Stock options exercised - value	1,944			(988)		2,932
Stock-based compensation expense	3,215			3,215
Deferral of executive and director compensation	419			419
Executive and director deferred compensation distributions shares			7,348
Executive and director deferred compensation distributions	0			(146)		146
Stockholders' Equity, Ending Balance at Dec. 31, 2014	$ 544,295	$ 48,163	$ 271	$ 238,560	$ 308,539	$ (51,238)
Shares Outstanding, Ending Balance at Dec. 31, 2014		2,000	24,512,910