Securities (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Amortized cost
Due in one year or less, amortized cost
Due after one year through five years, amortized cost	500
Due after five years through ten years, amortized cost	72,345
Due after ten years, amortized cost	89,000
Total amortized cost	566,509	454,060
Fair value
Due in one year or less, fair value
Due after one year through five years, fair value	500
Due after five years through ten years, fair value	73,724
Due after ten years, fair value	89,468
Total fair value	574,562	459,598
Mortgage-backed GSE securities: residential [Member]
Amortized cost
Mortgage-backed GSE securities: residential, amortized cost	404,563
Total amortized cost	404,563	403,943
Fair value
Mortgage-backed GSE securities: residential, fair value	410,557
Total fair value	$ 410,557	$ 408,535