Investment Securities, Available-for-sale Securities, Maturities (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Amortized Cost [Abstract]
Due in one year or less	$ 30,044
Due in one year through five years	142,230
Due after five years through ten years	35,060
Due after ten years	0
Amortized Cost	657,611
Fair Value [Abstract]
Due in one year or less	29,980
Due in one year through five years	140,094
Due after five years through ten years	34,416
Due after ten years	0
Fair Value	647,525
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Residential [Member]
Amortized Cost [Abstract]
Securities, amortized cost	362,665
Fair Value [Abstract]
Securities, fair value	357,683
Small Business Administration-Guaranteed Participation Securities [Member]
Amortized Cost [Abstract]
Securities, amortized cost	77,567
Fair Value [Abstract]
Securities, fair value	75,429
Mortgage-Backed Securities and Collateralized Mortgage Obligations-Commercial [Member]
Amortized Cost [Abstract]
Securities, amortized cost	10,045
Fair Value [Abstract]
Securities, fair value	$ 9,923