Investment Securities, Contractual Maturity (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Amortized Cost [Abstract]
Within One Year	$ 77,462
After One Year Through Five Years	1,074
After Five Years Through Ten Years	0
After Ten Years	0
Amortized Cost, Excluding Securities Without Single Maturity Date	78,536
Investment Securities Not Due at a Single Maturity Date - Mortgage-backed Securities	283,636
Amortized Cost	362,172
Fair/Book Value [Abstract]
Within One Year	77,470
After One Year Through Five Years	1,124
After Five Years Through Ten Years	0
After Ten Years	0
Fair/Book Value, Excluding Securities Without Single Maturity Date	78,594
Investment Securities Not Due at a Single Maturity Date - Mortgage-backed Securities	287,948
Fair/Book Value	366,542	404,639
Amortized Cost [Abstract]
Within One Year	2,747
After One Year Through Five Years	16,426
After Five Years Through Ten Years	9,845
After Ten Years	34,845
Amortized Cost, Excluding Securities Without Single Maturity Date	63,863
Investment Securities Not Due at a Single Maturity Date - Mortgage-backed Securities	0
Book Value	63,863	68,505
Fair Value [Abstract]
Within One Year	2,748
After One Year Through Five Years	16,633
After Five Years Through Ten Years	9,931
After Ten Years	35,323
Fair/Book Value, Excluding Securities Without Single Maturity Date	64,635
Investment Securities Not Due at a Single Maturity Date - Mortgage-backed Securities	0
Fair Value	$ 64,635	$ 68,690