Investment Securities (Maturity Schedule) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Available-for-sale Securities, Debt Maturities [Abstract]
Due in one year or less, amortized cost	$ 8,372
Due in one year or less, estimated fair value	8,412
Due after one year through five years, amortized cost	53,301
Due after one year through five years, estimated fair value	53,736
Due after five years through ten years, amortized cost	3,259
Due after five years through ten years, estimated fair value	3,219
Due after ten years, amortized cost	6,648
Due after ten years, estimated fair value	6,922
Total, amortized cost	71,580
Total, estimated fair value	72,289
Mortgage-backed securities, amortized cost	411,399
Mortgage-backed securities, estimated fair value	420,097
Total, amortized cost	482,979
Estimated fair value	$ 492,386	$ 431,306