Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share [Abstract]
Net income as reported	$ 8,766	$ 8,273	$ 14,951	$ 12,385
Preferred stock dividend	(438)	(438)	(875)	(875)
Accretion of preferred stock discount	(206)	(192)	(410)	(381)
Net income available to common shareholders	8,122	7,643	13,666	11,129
Impact of assumed conversions
Interest on 9% convertible trust preferred securities, net of income tax	371	371	742	742
Net income available to common shareholders and assumed conversions	$ 8,493	$ 8,014	$ 14,408	$ 11,871
Weighted average common shares outstanding (in shares)	17,833,000	17,140,000	17,808,000	15,601,000
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)	14,000	23,000	32,000	20,000
Diluted common shares outstanding (in shares)	19,286,000	18,602,000	19,279,000	17,060,000
Basic earnings per common share: (in dollars per share)	$ 0.46	$ 0.45	$ 0.77	$ 0.71
Diluted earnings per common share: (in dollars per share)	$ 0.44	$ 0.43	$ 0.75	$ 0.70
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)	1,100,000	782,266	1,000,000	925,049
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	324,074	324,074	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%