Investment Securities Held to Maturity Securities by Type (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	$ 386,954	$ 372,513
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	220	60
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(3,439)	(3,955)
Securities held to maturity, fair value	383,735	368,618
US Government Agencies Residential Mortgage-backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	4,266	4,297
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(19)	(4)
Securities held to maturity, fair value	4,247	4,293
US Government Agency Debt Securities Commercial [Domain]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	34,194	34,444
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(700)	(561)
Securities held to maturity, fair value	33,494	33,883
Residential Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	294,624	280,430
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	83	5
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(2,224)	(2,527)
Securities held to maturity, fair value	292,483	277,908
Obligations of U.S. Government-Sponsored Enterprises - Mortgage-Backed Securities - Commercial [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	14,536	14,675
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(51)	(142)
Securities held to maturity, fair value	14,485	14,533
Obligations of States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	39,134	38,667
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	137	55
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(443)	(721)
Securities held to maturity, fair value	38,828	38,001
Foreign Government Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	200	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(2)	0
Securities held to maturity, fair value	$ 198	$ 0