Investment Securities Schedule of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 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	220	$ 60
Held-to-maturity Securities	386,954	372,513
Securities held to maturity, fair value	383,735	$ 368,618
Due after 1 but within 5 years	2,824
Due after 5 but within 10 years	32,379
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	32,173
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	2,831
Due after 10 years	4,131
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	4,022
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis	39,334
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value	39,026
Held-to-maturity Securities, Debt Maturities, without Single Maturity Date, Net Carrying Amount	347,620
Held-to-maturity Securities, Debt Maturities, without Single Maturity Date, Fair Value	344,709
US Government Agencies Residential Mortgage-backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	38,500
Securities held to maturity, fair value	37,700
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	309,200
Securities held to maturity, fair value	$ 307,000