Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Investment Securities Available for Sale [Member]
Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)
Beginning Balance	$ 856	$ 1,672
Total net gain (losses) included in income:
Net impairment losses on investment securities	(255)	(816)
Ending Balance	601	856
Derivatives [Member]
Assets and Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Level 3)
Beginning Balance	(200)	5,539
Total net gain (losses) included in income:
Mortgage derivative gain, net	6,068	(5,739)
Ending Balance	$ 5,868	$ (200)