Stock Compensation Plans (Details 4) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Summary of nonvested stock compensation awards
Number of Nonvested shares outstanding, Beginning balance (in shares)	659,309	634,976	720,692	677,111
Weighted Average Exercise Price Nonvested shares, Beginning balance (in dollars per share)	$ 9.80	$ 7.87	$ 7.46	$ 8.81
Number of Nonvested shares outstanding, Granted (in shares)	379,425	390,750	372,750
Weighted Average Exercise Price Nonvested shares, Granted (in dollars per share)	$ 11.42	$ 8.62	$ 5.97
Number of Nonvested shares outstanding, Vested (in shares)	(311,630)	(453,744)	(322,003)
Weighted Average Exercise Price Nonvested shares, Vested (in dollars per share)	$ 7.80	$ 8.50	$ 8.57
Number of Nonvested shares outstanding, Forfeited (in shares)	(43,462)	(22,722)	(7,166)
Weighted Average Exercise Price Nonvested shares, Forfeited (in dollars per share)	$ 9.77	$ 7.59	$ 8.10
Number of Nonvested shares outstanding, Ending balance (in shares)	659,309	634,976	720,692	677,111
Weighted Average Exercise Price Nonvested shares, Ending balance (in dollars per share)	$ 9.80	$ 7.87	$ 7.46	$ 8.81