Investments (Details 3) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Amortized costs and estimated fair values of pledged investment securities, held-to-maturity
Amortized Cost	$ 125,196	$ 165,187
Held-to-maturity, at fair value	131,284	176,187
Federal Home Loan Bank Advances [Member]
Amortized costs and estimated fair values of pledged investment securities, held-to-maturity
Amortized Cost	12,178	21,260
Held-to-maturity, at fair value	13,175	22,431
Federal Reserve Bank Advances [Member]
Amortized costs and estimated fair values of pledged investment securities, held-to-maturity
Amortized Cost	113,018	143,927
Held-to-maturity, at fair value	$ 118,109	$ 153,756