Investment Securities, Part II (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($) securities	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) securities
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 86,122
After 1 through 5 years	197,503
After 5 through 10 years	135,153
After ten years	3,145
Fair Value	$ 421,923		$ 377,856
Available-for-sale, Weighted Average Yield, Maturities Year One (in hundredths)	1.68%
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)	2.69%
Available-for-sale , Weighted Average Yield, Maturities After 10 Years (in hundredths)	1.65%
Available-for-sale , Weighted Average Yield, Maturities (in hundredths)	2.32%
Available-for-sale, Full Tax-equivalent Yield, Maturities Year One (in hundredths)	1.84%
Available-for-sale, Full Tax-equivalent Yield, Maturities After 1 through 5 Years (in hundredths)	2.85%
Available-for-sale, Full Tax-equivalent Yield, Maturities After 5 through 10 years (in hundredths)	3.30%
Available-for-sale, Full Tax-equivalent Yield, Maturities After Ten Years (in hundredths)	2.18%
Available-for-sale, Full Tax-equivalent Yield, Maturities (in hundredths)	2.78%
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities	$ 43,973		53,650
Held To Maturity Weighted Average Yield Maturities Year One	2.30%
Held To Maturity Weighted Average Yield Maturities After 1 Through 5 Years	2.10%
Held To Maturity Weighted Average Yield Maturities After 5 Through 10 Years	2.33%
Held To Maturity Weighted Average Yield Maturities After 10 Years	0.00%
Held To Maturity Weighted Average Yield Maturities	2.31%
Held To Maturity Tax Equivalent Yield Maturities Year One	2.30%
Held To Maturity Tax Equivalent Yield Maturities After 1 Through 5 Years	2.10%
Held To Maturity Tax Equivalent Yield Maturities After 5 Through 10 Years	2.33%
Held To Maturity Tax Equivalent Yield Maturities After 10 Years	0.00%
Held To Maturity Tax Equivalent Yield Maturities	2.31%
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	$ 295,000		330,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	173,217		30,440
Less than 12 months, Unrealized Losses	(1,760)		(224)
12 months or longer, Fair Value	78,477		119,022
12 months or longer, Unrealized losses	(2,437)		(5,156)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	251,694		149,462
Total Unrealized Losses	$ 4,197		5,380
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	3,201
Market Value	2,141
Unrealized Gains (Losses)	(1,060)
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	80,168
After 1 through 5 years	41,566
After 5 through 10 years	0
After ten years	0
Fair Value	121,734		99,957
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount	24,543
Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount	9,714
Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount	9,716
Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount	0
Held-to-maturity Securities	43,973		53,650
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	31,099		7,289
Less than 12 months, Unrealized Losses	(150)		(46)
12 months or longer, Fair Value	53,504		75,030
12 months or longer, Unrealized losses	(590)		(1,312)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	84,603		82,319
Total Unrealized Losses	$ 740		$ 1,358
Number of securities in Unrealized Loss Positions | securities	11		16
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 0		$ 4,853
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	0		(12)
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	0		4,853
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	0		(12)
Obligations of states and political subdivisions
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	4,928
After 1 through 5 years	41,476
After 5 through 10 years	36,950
After ten years	940
Fair Value	84,294		78,084
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	25,006		3,586
Less than 12 months, Unrealized Losses	(461)		(19)
12 months or longer, Fair Value	1,153		4,416
12 months or longer, Unrealized losses	(89)		(94)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	26,159		8,002
Total Unrealized Losses	$ 550		$ 113
Number of securities in Unrealized Loss Positions | securities	2		10
Mortgage-backed securities: GSE residential
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	$ 1,026
After 1 through 5 years	110,463
After 5 through 10 years	98,203
After ten years	0
Fair Value	209,692		$ 195,401
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	115,116		19,565
Less than 12 months, Unrealized Losses	(1,145)		(159)
12 months or longer, Fair Value	21,679		37,224
12 months or longer, Unrealized losses	(698)		(802)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	136,795		56,789
Total Unrealized Losses	$ 1,843		$ 961
Number of securities in Unrealized Loss Positions | securities	7		11
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	2,141
Fair Value	2,141		$ 364
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	2,141		364
12 months or longer, Unrealized losses	(1,060)		(2,936)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,141		364
Total Unrealized Losses	$ 1,060		$ 2,936
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	3,998
After 5 through 10 years	0
After ten years	64
Fair Value	4,062		$ 4,050
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Less than 12 months, Fair Value	1,996		0
Less than 12 months, Unrealized Losses	(4)		0
12 months or longer, Fair Value	0		1,988
12 months or longer, Unrealized losses	0		(12)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,996		1,988
Total Unrealized Losses	$ 4		$ 12