Investment Securities, Part II (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($) securities	Dec. 31, 2015 USD ($) securities	Dec. 31, 2014 USD ($) securities	Dec. 31, 2013 USD ($)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 57,802,000	$ 57,802,000
After 1 through 5 years	228,065,000	228,065,000
After 5 through 10 years	228,980,000	228,980,000
After ten years	4,001,000	4,001,000
Fair Value	518,848,000	$ 518,848,000	$ 377,856,000
Available-for-sale, Weighted Average Yield, Maturities Year One (in hundredths)		1.83%
Available-for-sale , Weighted Average Yield, Maturities After 1 through 5 Years (in hundredths)		2.36%
Available-for-sale, Weighted Average Yield, Maturities After 5 through 10 Years (in hundredths)		2.71%
Available-for-sale , Weighted Average Yield, Maturities After 10 Years (in hundredths)		2.05%
Available-for-sale , Weighted Average Yield, Maturities (in hundredths)		2.45%
Available-for-sale, Full Tax-equivalent Yield, Maturities Year One (in hundredths)		2.23%
Available-for-sale, Full Tax-equivalent Yield, Maturities After 1 through 5 Years (in hundredths)		2.81%
Available-for-sale, Full Tax-equivalent Yield, Maturities After 5 through 10 years (in hundredths)		3.23%
Available-for-sale, Full Tax-equivalent Yield, Maturities After Ten Years (in hundredths)		2.91%
Available-for-sale, Full Tax-equivalent Yield, Maturities (in hundredths)		2.93%
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	50,632,000	$ 50,632,000
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	29,486,000	29,486,000
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	5,090,000	5,090,000
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	0	0
Held-to-maturity, at amortized cost (estimated fair value of $85,737 at December 31, 2015 and $53,937 at December 31, 2014)	85,208,000	$ 85,208,000	53,650,000
Held To Maturity Weighted Average Yield Maturities Year One		1.99%
Held To Maturity Weighted Average Yield Maturities After 1 Through 5 Years		2.09%
Held To Maturity Weighted Average Yield Maturities After 5 Through 10 Years		2.06%
Held To Maturity Weighted Average Yield Maturities After 10 Years		0.00%
Held To Maturity Weighted Average Yield Maturities		2.03%
Held To Maturity Tax Equivalent Yield Maturities Year One		1.99%
Held To Maturity Tax Equivalent Yield Maturities After 1 Through 5 Years		2.09%
Held To Maturity Tax Equivalent Yield Maturities After 5 Through 10 Years		2.06%
Held To Maturity Tax Equivalent Yield Maturities After 10 Years		0.00%
Held To Maturity Tax Equivalent Yield Maturities		2.03%
Tax rate used to calculate tax-equivalent yields (in hundredths)		35.00%
Percentage investment book value exceeds total stockholders' equity (in hundredths)		10.00%
Investment Securities Pledged as Collateral	403,702,000	$ 403,702,000	330,122,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	204,325,000	204,325,000	30,440,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,049,000	1,049,000	224,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	35,867,000	35,867,000	119,022,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,984,000	1,984,000	5,156,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	240,192,000	240,192,000	149,462,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 3,033,000	3,033,000	5,380,000
Details of Trust Preferred Securities [Abstract]
Coupon Rate of Trust Preferred Security	floating rate coupon of 3-month LIBOR plus 90 basis points
Number of Ratios Utilized in OTTI Credit Model	29
OTTI Cash Flow Initial Default Rate	2.00%
Period For Initial Default Rate Used In OTTI Analysis	two years
Default Rate Applied For Remainder Of OTTI Analysis	36 basis points
Recovery Rate Used In OTTI Cash Flow Analysis	10.00%
Credit losses on trust preferred securities held [Abstract]
Beginning of period		1,111,000	1,111,000	$ 3,989,000
Additions related to OTTI losses not previously recognized		0	0	0
Reductions due to sales / (recoveries)		0	0	(2,878,000)
Reductions due to change in intent or likelihood of sale		0	0	0
Additions related to increases in previously recognized OTTI losses		0	0	0
Reductions due to increases in expected cash flows		0	0	0
End of period	$ 1,111,000	1,111,000	1,111,000	$ 1,111,000
Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value	50,855,000	50,855,000
Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value	29,804,000	29,804,000
Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value	5,078,000	5,078,000
Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value	0	0
Held-to-maturity Securities, Fair Value	85,737,000	85,737,000	53,937,000
PreTSL XXVIII
Details of Trust Preferred Securities [Abstract]
Book Value	3,130,000	3,130,000
Market Value	1,906,000	1,906,000
Unrealized Gains (Losses)	(1,224,000)	(1,224,000)
Other-than- temporary Impairment Recorded To-date		(1,111,000)
U.S. Treasury securities and obligations of U.S. government corporations & agencies
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	49,191,000	49,191,000
After 1 through 5 years	40,950,000	40,950,000
After 5 through 10 years	0	0
After ten years	0	0
Fair Value	90,141,000	90,141,000	99,957,000
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	50,632,000	50,632,000
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	29,486,000	29,486,000
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	5,090,000	5,090,000
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	0	0
Held-to-maturity, at amortized cost (estimated fair value of $85,737 at December 31, 2015 and $53,937 at December 31, 2014)	85,208,000	85,208,000	53,650,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	34,942,000	34,942,000	7,289,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	142,000	142,000	46,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	12,971,000	12,971,000	75,030,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	126,000	126,000	1,312,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	47,913,000	47,913,000	82,319,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 268,000	$ 268,000	$ 1,358,000
Number of securities in Unrealized Loss Positions	6	6	16
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 35,845,000	$ 35,845,000	$ 4,853,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(214,000)	(214,000)	(12,000)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	35,845,000	35,845,000	4,853,000
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	(214,000)	(214,000)	(12,000)
Credit losses on trust preferred securities held [Abstract]
Held-to-maturity Securities, Fair Value	85,737,000	85,737,000	53,937,000
Obligations of states and political subdivisions
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	8,373,000	8,373,000
After 1 through 5 years	45,705,000	45,705,000
After 5 through 10 years	54,607,000	54,607,000
After ten years	2,032,000	2,032,000
Fair Value	110,717,000	110,717,000	78,084,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	3,168,000	3,168,000	3,586,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	32,000	32,000	19,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	979,000	979,000	4,416,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	23,000	23,000	94,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,147,000	4,147,000	8,002,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 55,000	$ 55,000	$ 113,000
Number of securities in Unrealized Loss Positions | securities	2	2	10
Mortgage-backed securities
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 238,000	$ 238,000
After 1 through 5 years	137,443,000	137,443,000
After 5 through 10 years	174,373,000	174,373,000
After ten years	0	0
Fair Value	312,054,000	312,054,000	$ 195,401,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	164,249,000	164,249,000	19,565,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	841,000	841,000	159,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	20,011,000	20,011,000	37,224,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	611,000	611,000	802,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	184,260,000	184,260,000	56,789,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 1,452,000	$ 1,452,000	$ 961,000
Number of securities in Unrealized Loss Positions | securities	7	7	11
Trust preferred securities
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 0	$ 0
After 1 through 5 years	0	0
After 5 through 10 years	0	0
After ten years	1,906,000	1,906,000
Fair Value	1,906,000	1,906,000	$ 364,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	0	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	1,906,000	1,906,000	364,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,224,000	1,224,000	2,936,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,906,000	1,906,000	364,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 1,224,000	$ 1,224,000	$ 2,936,000
Number of securities in Unrealized Loss Positions | securities	1	1	1
Other securities
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 0	$ 0
After 1 through 5 years	3,967,000	3,967,000
After 5 through 10 years	0	0
After ten years	63,000	63,000
Fair Value	4,030,000	4,030,000	$ 4,050,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,966,000	1,966,000	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	34,000	34,000	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0	1,988,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0	12,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,966,000	1,966,000	1,988,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 34,000	$ 34,000	$ 12,000