Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Net income as reported	$ 11,033	$ 8,766	$ 21,073	$ 14,951
Preferred stock dividend	0	(438)	0	(875)
Accretion of preferred stock discount	0	(206)	0	(410)
Net income available to common shareholders	11,033	8,122	21,073	13,666
Impact of assumed conversions
Interest on 9% convertible trust preferred securities, net of income tax	354	371	709	742
Net income available to common shareholders and assumed conversions	$ 11,387	$ 8,493	$ 21,782	$ 14,408
Weighted average common shares outstanding (in shares)	18,119,000	17,833,000	18,052,000	17,808,000
Incremental shares from assumed conversions of convertible trust preferred securities (in shares)	1,439,000	1,439,000	1,439,000	1,439,000
Additional dilutive common stock equivalents (in shares)	153,000	14,000	115,000	32,000
Weighted average diluted common shares outstanding (in shares)	19,711,000	19,286,000	19,606,000	19,279,000
Basic earnings per common share: (in dollars per share)	$ 0.61	$ 0.46	$ 1.17	$ 0.77
Diluted earnings per common share: (in dollars per share)	$ 0.58	$ 0.44	$ 1.11	$ 0.75
Antidilutive Securities Excluded from Computation of Earnings Per Share
Common stock equivalents excluded from earnings per share calculations due to anti-dilutive effect (in shares)	600,000	1,148,812	547,356	1,000,000
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share
Common stock equivalents excluded from earnings per share calculations due to anti-dilutive effect (in shares)		324,074	14,324	324,074
Convertible Debt Securities
Debt Instrument, Interest Rate, Stated Percentage [Abstract]
Convertible trust preferred securities, interest rate, stated percentage	9.00%	9.00%	9.00%	9.00%