Investment Securities, Part II (Details) $ in Thousands	9 Months Ended
Sep. 30, 2016 USD ($) securities	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) securities
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 28,741
After 1 through 5 years	439,789
After 5 through 10 years	83,861
After ten years	4,235
Fair Value	$ 556,626		$ 518,848
Available-for-sale, Weighted Average Yield, Maturities Year One (in hundredths)	2.34%
Available-for-sale , Weighted Average Yield, Maturities After 1 through 5 Years (in hundredths)	2.35%
Available-for-sale, Weighted Average Yield, Maturities After 5 through 10 Years (in hundredths)	2.63%
Available-for-sale , Weighted Average Yield, Maturities After 10 Years (in hundredths)	2.22%
Available-for-sale , Weighted Average Yield, Maturities (in hundredths)	2.39%
Available-for-sale, Full Tax-equivalent Yield, Maturities Year One (in hundredths)	3.33%
Available-for-sale, Full Tax-equivalent Yield, Maturities After 1 through 5 Years (in hundredths)	2.69%
Available-for-sale, Full Tax-equivalent Yield, Maturities After 5 through 10 years (in hundredths)	3.99%
Available-for-sale, Full Tax-equivalent Yield, Maturities After Ten Years (in hundredths)	3.09%
Available-for-sale, Full Tax-equivalent Yield, Maturities (in hundredths)	2.92%
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities	$ 101,679		85,208
Held To Maturity Weighted Average Yield Maturities Year One	1.80%
Held To Maturity Weighted Average Yield Maturities After 1 Through 5 Years	2.11%
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	1.89%
Held To Maturity Tax Equivalent Yield Maturities Year One	1.80%
Held To Maturity Tax Equivalent Yield Maturities After 1 Through 5 Years	2.11%
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	1.89%
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	$ 470,000		404,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	20,616		204,325
Less than 12 months, Unrealized Losses	(110)		(1,049)
12 months or longer, Fair Value	9,964		35,867
12 months or longer, Unrealized losses	(1,505)		(1,984)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	30,580		240,192
Total Unrealized Losses	$ 1,615		3,033
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	$ 1,111
Additions related to OTTI losses not previously recognized	0	0
Reductions due to sales / (recoveries)	0	0
Reductions due to change in intent or likelihood of sale	0	0
Additions related to increases in previously recognized OTTI losses	0	0
Reductions due to increases in expected cash flows	0	0
End of period	1,111	$ 1,111
PreTSL XXVIII [Member]
Details of Trust Preferred Securities [Abstract]
Book Value	3,075
Fair Value	1,661
Unrealized Gains (Losses)	(1,414)
Other-than- temporary Impairment Recorded To-date	(1,111)
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	15,531
After 1 through 5 years	28,563
After 5 through 10 years	4,642
After ten years	0
Fair Value	48,736		90,141
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	72,030
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	24,570
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	5,079
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	0
Held-to-maturity Securities	101,679		85,208
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	0		34,942
Less than 12 months, Unrealized Losses	0		(142)
12 months or longer, Fair Value	0		12,971
12 months or longer, Unrealized losses	0		(126)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0		47,913
Total Unrealized Losses	0		$ 268
Number of securities in Unrealized Loss Positions \| securities			6
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	14,928		$ 35,845
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(64)		(214)
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	14,928		35,845
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	(64)		(214)
Obligations of states and political subdivisions
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	11,722
After 1 through 5 years	85,629
After 5 through 10 years	61,104
After ten years	2,464
Fair Value	160,919		110,717
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	13,235		3,168
Less than 12 months, Unrealized Losses	(93)		(32)
12 months or longer, Fair Value	0		979
12 months or longer, Unrealized losses	0		(23)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	13,235		4,147
Total Unrealized Losses	93		$ 55
Number of securities in Unrealized Loss Positions \| securities			2
Mortgage-backed securities: GSE residential
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	1,488
After 1 through 5 years	321,587
After 5 through 10 years	18,115
After ten years	0
Fair Value	341,190		$ 312,054
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	7,381		164,249
Less than 12 months, Unrealized Losses	(17)		(841)
12 months or longer, Fair Value	6,309		20,011
12 months or longer, Unrealized losses	(85)		(611)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	13,690		184,260
Total Unrealized Losses	$ 102		$ 1,452
Number of securities in Unrealized Loss Positions \| securities	9		7
Trust preferred securities
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 0
After 1 through 5 years	0
After 5 through 10 years	0
After ten years	1,661
Fair Value	1,661		$ 1,906
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	0		0
Less than 12 months, Unrealized Losses	0		0
12 months or longer, Fair Value	1,661		1,906
12 months or longer, Unrealized losses	(1,414)		(1,224)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,661		1,906
Total Unrealized Losses	$ 1,414		$ 1,224
Number of securities in Unrealized Loss Positions \| securities	1		1
Other securities
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 0
After 1 through 5 years	4,010
After 5 through 10 years	0
After ten years	110
Fair Value	4,120		$ 4,030
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	0		1,966
Less than 12 months, Unrealized Losses	0		(34)
12 months or longer, Fair Value	1,994		0
12 months or longer, Unrealized losses	(6)		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,994		1,966
Total Unrealized Losses	$ 6		$ 34

The yield on an available-for-sale government security, when the effect of reduced taxes are taken into account, for securities that mature. The full tax-equivalent yield show what yield a fully taxable security would have to give, in order to be equivalent to a tax free government security.

No definition available.