Investment Securities Schedule of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Due within 1 year	$ 0
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	646	$ 60
Held-to-maturity Securities	450,886	372,513
Securities held to maturity, fair value	449,127	$ 368,618
Due after 1 but within 5 years	3,118
Due after 5 but within 10 years	32,061
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	32,354
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	3,142
Due after 10 years	5,624
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	5,600
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis	40,803
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value	41,096
Held-to-maturity Securities, Debt Maturities, without Single Maturity Date, Net Carrying Amount	410,083
Held-to-maturity Securities, Debt Maturities, without Single Maturity Date, Fair Value	408,031
US Government Agencies Residential Mortgage-backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	62,900
Securities held to maturity, fair value	62,200
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	347,200
Securities held to maturity, fair value	$ 345,800