Condensed 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, 2012	$ 335,428	$ 96,325	$ 246	$ 180,289	$ 117,048	$ (58,480)
Shares Outstanding, Beginning Balance at Dec. 31, 2012		4,000	21,687,253
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	137,162				137,162
Fair value over carrying value of preferred shares redeemed	0	2,190			(2,190)
Dividends, Preferred Stock	(2,438)				(2,438)
Common share issuance	2,461,000		2,461,000
Net proceeds from issuance of common shares	54,617		25	54,592
Preferred shares redeemed during period	2,000	(2,000)
Preferred shares redeemed, value	(50,352)	(50,352)
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	383			383
Stock options exercised, shares			184,832
Stock options exercised	2,640			(1,031)		3,671
Stock-based compensation expense	1,835			1,835
Deferral of executive and director compensation	305			305
Executive and director deferred compensation distributions shares			24,858
Executive and director deferred compensation distributions	0			(493)		493
Stockholders' Equity, Ending Balance at Sep. 30, 2013	$ 479,580	$ 48,163	$ 271	$ 235,880	$ 249,582	$ (54,316)
Shares Outstanding, Ending Balance at Sep. 30, 2013		2,000	24,357,943