Securities, Held to Maturity (Details) $ in Thousands	Dec. 31, 2016 USD ($) Position	Dec. 31, 2015 USD ($) Position
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 527,948	$ 471,031
Unrealized gains	1,581	3,794
Unrealized losses	4,479	1,685
Estimated fair value	525,050	473,140
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	286,063	117,129
12 months or longer	35,209	41,523
Total	321,272	158,652
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(3,290)	(406)
12 months or longer	(1,189)	(1,279)
Total	$ (4,479)	$ (1,685)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	172	16
12 months or longer | Position	4	4
Total | Position	176	20
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Within one year	$ 37,187
From one to five years	27,956
From five to ten years	122,228
After ten years	340,577
Amortized cost	527,948	$ 471,031
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Within one year	37,199
From one to five years	28,019
From five to ten years	121,697
After ten years	338,135
Total, Fair Value	525,050	473,140
Mortgage-Backed [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	95,492	9,325
12 months or longer	0	0
Total	95,492	9,325
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(1,176)	(107)
12 months or longer	0	0
Total	$ (1,176)	$ (107)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	5	1
12 months or longer | Position	0	0
Total | Position	5	1
Mortgage-backed Securities, Issued by US Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 96,668	$ 9,432
Unrealized gains	0	0
Unrealized losses	1,176	107
Estimated fair value	95,492	9,325
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	96,668	9,432
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	95,492	9,325
Mortgage-backed Securities, Issued by US Government Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	533	611
Unrealized gains	87	95
Unrealized losses	0	0
Estimated fair value	620	706
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	533	611
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	620	706
Collateralized Mortgage Obligations [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	108,587	105,604
12 months or longer	35,209	41,523
Total	143,796	147,127
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(319)	(281)
12 months or longer	(1,189)	(1,279)
Total	$ (1,508)	$ (1,560)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	12	12
12 months or longer | Position	4	4
Total | Position	16	16
Collateralized Mortgage Obligations, Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 225,213	$ 272,550
Unrealized gains	1,060	1,411
Unrealized losses	1,508	1,560
Estimated fair value	224,765	272,401
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	225,213	272,550
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	224,765	272,401
State & Municipal [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	205,534	188,438
Unrealized gains	434	2,288
Unrealized losses	1,795	18
Estimated fair value	204,173	190,708
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	81,984	2,200
12 months or longer	0	0
Total	81,984	2,200
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(1,795)	(18)
12 months or longer	0	0
Total	$ (1,795)	$ (18)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	155	3
12 months or longer | Position	0	0
Total | Position	155	3
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	$ 205,534	$ 188,438
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	$ 204,173	$ 190,708