Investment Securities Available-for-Sale (Details 1) $ in Thousands	Sep. 30, 2017 USD ($) Number	Dec. 31, 2016 USD ($) Number
Available-for-sale securities in a continuous loss position, number of securities | Number	150	157
Available-for-sale securities in a continuous loss position, less than 12 months, estimated fair value	$ 309,803	$ 361,079
Available-for-sale securities in a continuous loss position, less than 12 months, unrealized losses	2,743	5,285
Available-for-sale securities in a continuous loss position, 12 months or greater, estimated fair value	84,219	23,170
Available-for-sale securities in a continuous loss position, 12 months or greater, unrealized losses	1,570	619
Available-for-sale securities in a continuous loss position, estimated fair value	394,022	384,249
Available-for-sale securities in a continuous loss position, unrealized losses	$ 4,313	$ 5,904
US Agency Securities [Member]
Available-for-sale securities in a continuous loss position, number of securities | Number	32	27
Available-for-sale securities in a continuous loss position, less than 12 months, estimated fair value	$ 97,832	$ 88,991
Available-for-sale securities in a continuous loss position, less than 12 months, unrealized losses	1,101	1,764
Available-for-sale securities in a continuous loss position, 12 months or greater, estimated fair value	28,299	3,768
Available-for-sale securities in a continuous loss position, 12 months or greater, unrealized losses	423	38
Available-for-sale securities in a continuous loss position, estimated fair value	126,131	92,759
Available-for-sale securities in a continuous loss position, unrealized losses	$ 1,524	$ 1,802
Residential Mortgage Backed Securities [Member]
Available-for-sale securities in a continuous loss position, number of securities | Number	113	112
Available-for-sale securities in a continuous loss position, less than 12 months, estimated fair value	$ 198,670	$ 232,347
Available-for-sale securities in a continuous loss position, less than 12 months, unrealized losses	1,523	3,110
Available-for-sale securities in a continuous loss position, 12 months or greater, estimated fair value	55,920	19,402
Available-for-sale securities in a continuous loss position, 12 months or greater, unrealized losses	1,147	581
Available-for-sale securities in a continuous loss position, estimated fair value	254,590	251,749
Available-for-sale securities in a continuous loss position, unrealized losses	$ 2,670	$ 3,691
Municipal Bonds [Member]
Available-for-sale securities in a continuous loss position, number of securities | Number	5	16
Available-for-sale securities in a continuous loss position, less than 12 months, estimated fair value	$ 13,301	$ 34,743
Available-for-sale securities in a continuous loss position, less than 12 months, unrealized losses	119	400
Available-for-sale securities in a continuous loss position, estimated fair value	13,301	34,743
Available-for-sale securities in a continuous loss position, unrealized losses	$ 119	$ 400
Corporate Bonds [Member]
Available-for-sale securities in a continuous loss position, number of securities | Number		2
Available-for-sale securities in a continuous loss position, less than 12 months, estimated fair value		$ 4,998
Available-for-sale securities in a continuous loss position, less than 12 months, unrealized losses		11
Available-for-sale securities in a continuous loss position, estimated fair value		4,998
Available-for-sale securities in a continuous loss position, unrealized losses		$ 11