Stock Compensation Plans (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of nonvested stock compensation awards
Number of Nonvested shares outstanding, Beginning balance (in shares)	660,059	635,726	721,442
Weighted Average Exercise Price Nonvested shares, Beginning balance (in dollars per share)	$ 9.80	$ 7.87	$ 7.46
Number of Nonvested shares outstanding, Granted (in shares)	417,420	379,425	390,750
Weighted Average Exercise Price Nonvested shares, Granted (in dollars per share)	$ 12.36	$ 11.42	$ 8.62
Number of Nonvested shares outstanding, Vested (in shares)	(317,635)	(311,630)	(453,744)
Weighted Average Exercise Price Nonvested shares, Vested (in dollars per share)	$ 8.99	$ 7.80	$ 8.50
Number of Nonvested shares outstanding, Forfeited (in shares)	(25,232)	(43,462)	(22,722)
Weighted Average Exercise Price Nonvested shares, Forfeited (in dollars per share)	$ 11.59	$ 9.77	$ 7.59
Number of Nonvested shares outstanding, Ending balance (in shares)	734,612	660,059	635,726
Weighted Average Exercise Price Nonvested shares, Ending balance (in dollars per share)	$ 11.55	$ 9.80	$ 7.87