Securities, Held to Maturity (Details) $ in Thousands	Jun. 30, 2016 USD ($) Position	Dec. 31, 2015 USD ($) Position
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 500,840	$ 471,031
Unrealized gains	11,777	3,794
Unrealized losses	(268)	(1,685)
Estimated fair value	512,349	473,140
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	918	117,129
12 Months or Longer, Fair Value	39,767	41,523
Total, Fair Value	40,685	158,652
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses	(12)	(406)
12 Months or Longer, Unrealized Losses	(256)	(1,279)
Total, Unrealized Losses	$ (268)	$ (1,685)
Unrealized Loss Position, Number of Positions [Abstract]
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | Position	2	16
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater Than or Equal to One Year | Position	4	4
Total, Number of Positions | Position	6	20
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Within one year	$ 39,152
From one to five years	23,575
From five to ten years	118,985
After ten years	319,128
Amortized cost	500,840	$ 471,031
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Within one year	39,185
From one to five years	23,863
From five to ten years	122,641
After ten years	326,660
Total, Fair Value	512,349	473,140
Mortgage-Backed [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value		9,325
12 Months or Longer, Fair Value		0
Total, Fair Value		9,325
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(107)
12 Months or Longer, Unrealized Losses		0
Total, Unrealized Losses		$ (107)
Unrealized Loss Position, Number of Positions [Abstract]
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | Position		1
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater Than or Equal to One Year | Position		0
Total, Number of Positions | Position		1
Mortgage-backed Securities, Issued by US Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	51,206	$ 9,432
Unrealized gains	505	0
Unrealized losses	0	(107)
Estimated fair value	51,711	9,325
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	51,206	9,432
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	51,711	9,325
Mortgage-backed Securities, Issued by US Government Agency Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	566	611
Unrealized gains	105	95
Unrealized losses	0	0
Estimated fair value	671	706
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	566	611
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	671	706
Collateralized Mortgage Obligations [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	0	105,604
12 Months or Longer, Fair Value	39,767	41,523
Total, Fair Value	39,767	147,127
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses	0	(281)
12 Months or Longer, Unrealized Losses	(256)	(1,279)
Total, Unrealized Losses	$ (256)	$ (1,560)
Unrealized Loss Position, Number of Positions [Abstract]
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | Position	0	12
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater Than or Equal to One Year | Position	4	4
Total, Number of Positions | Position	4	16
Collateralized Mortgage Obligations, Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 251,069	$ 272,550
Unrealized gains	6,259	1,411
Unrealized losses	(256)	(1,560)
Estimated fair value	257,072	272,401
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	251,069	272,550
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	257,072	272,401
State & Municipal [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	197,999	188,438
Unrealized gains	4,908	2,288
Unrealized losses	(12)	(18)
Estimated fair value	202,895	190,708
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	918	2,200
12 Months or Longer, Fair Value	0	0
Total, Fair Value	918	2,200
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses	(12)	(18)
12 Months or Longer, Unrealized Losses	0	0
Total, Unrealized Losses	$ (12)	$ (18)
Unrealized Loss Position, Number of Positions [Abstract]
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | Position	2	3
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater Than or Equal to One Year | Position	0	0
Total, Number of Positions | Position	2	3
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized cost	$ 197,999	$ 188,438
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	$ 202,895	$ 190,708