Regulatory Matters (Details Textual) (USD $)	1 Months Ended					3 Months Ended		12 Months Ended
	Feb. 28, 2013	Jan. 31, 2013	Nov. 30, 2012	Oct. 31, 2012	May 31, 2010	Mar. 31, 2013	Mar. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2009
Regulatory Matters (Textual) [Abstract]
Maximum amount of dividends distributed by bank to holding company without prior regulatory approval								$ 23,000,000
Cash dividend on common stock		$ 0.10		$ 0.09
Dividend declared date		Jan. 10, 2013		Oct. 11, 2012
Dividend payable date						Mar. 08, 2013		Dec. 10, 2012
Dividend payable date of record	Feb. 08, 2013		Nov. 09, 2012
Dividend suspended date							Apr. 01, 2010
Outstanding balance of trust preferred securities								32,000,000	32,000,000
Aggregate amount of restricted core elements allowed in Tier 1 capital								25.00%
Trusted preferred securities issued date					before May 19, 2010
Maximum level of consolidated aggregate assets allowing for inclusion of trust preferred securities in Tier Capital under Dodd-Frank Act										$ 15,000,000,000