Securities, Held to Maturity (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) Position	Dec. 31, 2016 USD ($) Position
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 515,793	$ 527,948
Unrealized gains	2,007	1,581
Unrealized losses	4,146	4,479
Estimated fair value	513,654	525,050
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	245,212	286,063
12 months or longer	33,841	35,209
Total	279,053	321,272
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(2,869)	(3,290)
12 months or longer	(1,277)	(1,189)
Total	$ (4,146)	$ (4,479)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	92	172
12 months or longer | Position	4	4
Total | Position	96	176
OTTI loss realized on equity investment	$ 1,300	$ 0
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Within one year	38,266
From one to five years	30,155
From five to ten years	126,026
After ten years	321,346
Amortized cost	515,793	527,948
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Within one year	38,275
From one to five years	30,330
From five to ten years	126,080
After ten years	318,969
Fair value	513,654	525,050
Mortgage-Backed [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	93,622	95,492
12 months or longer	0	0
Total	93,622	95,492
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(1,227)	(1,176)
12 months or longer	0	0
Total	$ (1,227)	$ (1,176)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	5	5
12 months or longer | Position	0	0
Total | Position	5	5
Mortgage-backed Securities, Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 94,849	$ 96,668
Unrealized gains	0	0
Unrealized losses	1,227	1,176
Estimated fair value	93,622	95,492
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	94,849	96,668
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Fair value	93,622	95,492
Mortgage-backed Securities, U.S. Government Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	491	533
Unrealized gains	76	87
Unrealized losses	0	0
Estimated fair value	567	620
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	491	533
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Fair value	567	620
Collateralized Mortgage Obligations [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	103,287	108,587
12 months or longer	33,841	35,209
Total	137,128	143,796
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(360)	(319)
12 months or longer	(1,277)	(1,189)
Total	$ (1,637)	$ (1,508)
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	$ 215,639	$ 225,213
Unrealized gains	959	1,060
Unrealized losses	1,637	1,508
Estimated fair value	214,961	224,765
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	215,639	225,213
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Fair value	214,961	224,765
State & Municipal [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	204,814	205,534
Unrealized gains	972	434
Unrealized losses	1,282	1,795
Estimated fair value	204,504	204,173
Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months	48,303	81,984
12 months or longer	0	0
Total	48,303	81,984
Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	(1,282)	(1,795)
12 months or longer	0	0
Total	$ (1,282)	$ (1,795)
Unrealized Loss Position, Number of Positions [Abstract]
Less than 12 months | Position	75	155
12 months or longer | Position	0	0
Total | Position	75	155
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	$ 204,814	$ 205,534
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Fair value	$ 204,504	$ 204,173