Investment Securities, Contract Maturity (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Amortized Cost [Abstract]
Within One Year	$ 19,689
After One Year Through Five Years	56,416
After Five Years Through Ten Years	3,279
After Ten Years	0
Amortized cost, before single maturity date	79,384
Investment Securities Not Due at a Single Maturity Date - Mortgage-backed Securities	342,963
Amortized cost, Total	422,347
Fair/Book Value [Abstract]
Within One Year	19,756
After One Year Through Five Years	56,526
After Five Years Through Ten Years	3,406
After Ten Years	0
Fair/Book Value, before single maturity date	79,688
Investment Securities Not Due at a Single Maturity Date - Mortgage-backed Securities	342,077
Fair/Book Value, Total	421,765	417,991	463,177
Amortized Cost [Abstract]
Within One Year	1,625
After One Year Through Five Years	18,543
After Five Years Through Ten Years	31,911
After Ten Years	18,761
Amortized cost, before single maturity date	70,840
Investment Securities Not Due at a Single Maturity Date - Mortgage-backed Securities	121
Amortized cost, Total	70,961	68,392	68,960
Fair Value [Abstract]
Within One Year	1,630
After One Year Through Five Years	18,876
After Five Years Through Ten Years	32,538
After Ten Years	18,020
Fair/Book Value, before single maturity date	71,064
Investment Securities Not Due at a Single Maturity Date - Mortgage-backed Securities	122
Fair Value	$ 71,186