Investment Securities Available-for-Sale (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2011	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Trust preferred securities [Member]	Sep. 30, 2011 Trust preferred securities [Member]	Sep. 30, 2012 Trust preferred securities [Member]	Sep. 30, 2011 Trust preferred securities [Member]
Losses recognized in earnings for trust preferred securities held and not intended to be sold
Beginning balance	$ 261	$ 10,472	$ 261	$ 10,472	$ 10,472	$ 351		$ 10,845	$ 10,674	$ 10,674	$ 10,472
Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized	90	202								171	202
Investment securities available-for-sale (Note 3)						175,024	185,916	(10,494)		(10,494)
Ending balance					$ 10,674	$ 351		$ 351	$ 10,674	$ 351	$ 10,674