Investment Securities, Available-for-sale Securities, Maturities (Details) $ in Thousands	Sep. 30, 2015 USD ($)
Amortized Cost [Abstract]
Due in one year or less	$ 2,459
Due in one year through five years	317,594
Due after five years through ten years	305,162
Due after ten years	18
Amortized Cost	625,233
Fair Value [Abstract]
Due in one year or less	2,452
Due in one year through five years	318,781
Due after five years through ten years	303,261
Due after ten years	18
Fair Value	$ 624,512