Investment Securities, Part II (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) securities	Dec. 31, 2017 USD ($) securities	Dec. 31, 2016 USD ($)
Debt Securities, Available-for-sale [Line Items]
Proceeds from Sale of Available-for-sale Securities	$ 13,152,000	$ 159,663,000	$ 70,757,000
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	172,560,000
After 1 through 5 years	302,833,000
After 5 through 10 years	215,444,000
After ten years	1,437,000
Fair Value	$ 692,274,000	578,579,000
Available-for-sale, Weighted Average Yield, Maturities Year One (in hundredths)	2.57%
Available-for-sale , Weighted Average Yield, Maturities After 1 through 5 Years (in hundredths)	2.83%
Available-for-sale, Weighted Average Yield, Maturities After 5 through 10 Years (in hundredths)	2.93%
Available-for-sale , Weighted Average Yield, Maturities After 10 Years (in hundredths)	3.10%
Available-for-sale , Weighted Average Yield, Maturities (in hundredths)	2.80%
Available-for-sale, Full Tax-equivalent Yield, Maturities Year One (in hundredths)	2.70%
Available-for-sale, Full Tax-equivalent Yield, Maturities After 1 through 5 Years (in hundredths)	3.14%
Available-for-sale, Full Tax-equivalent Yield, Maturities After 5 through 10 years (in hundredths)	3.34%
Available-for-sale, Full Tax-equivalent Yield, Maturities After Ten Years (in hundredths)	4.14%
Available-for-sale, Full Tax-equivalent Yield, Maturities (in hundredths)	3.10%
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost	$ 39,995,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost	29,441,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost	0
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Amortized Cost	0
Held-to-maturity, at amortized cost (estimated fair value of $67,909 and $68,457 at December 31, 2018 and 2017, respectively)	$ 69,436,000	$ 69,332,000
Held To Maturity Weighted Average Yield Maturities Year One	1.76%
Held To Maturity Weighted Average Yield Maturities After 1 Through 5 Years	2.08%
Held To Maturity Weighted Average Yield Maturities After 5 Through 10 Years	0.00%
Held To Maturity Weighted Average Yield Maturities After 10 Years	0.00%
Held To Maturity Weighted Average Yield Maturities	1.90%
Held To Maturity Tax Equivalent Yield Maturities Year One	1.76%
Held To Maturity Tax Equivalent Yield Maturities After 1 Through 5 Years	2.08%
Held To Maturity Tax Equivalent Yield Maturities After 5 Through 10 Years	0.00%
Held To Maturity Tax Equivalent Yield Maturities After 10 Years	0.00%
Held To Maturity Tax Equivalent Yield Maturities	1.90%
Tax rate used to calculate tax-equivalent yields (in hundredths)	21.00%	35.00%
Percentage investment book value exceeds total stockholders' equity (in hundredths)	10.00%
Available-for-sale Securities, Restricted	$ 628,307,000	$ 479,398,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	136,312,000	289,151,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,748,000)	(3,251,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	319,611,000	82,396,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(9,513,000)	(2,613,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	455,923,000	371,547,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(11,261,000)	(5,864,000)
Credit losses on trust preferred securities held [Abstract]
Beginning of period	1,111,000	1,111,000	1,111,000
Additions related to OTTI losses not previously recognized	0	0	0
Reductions due to sales / (recoveries)	(1,111,000)	0	0
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	0	1,111,000	1,111,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value	38,790,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value	29,119,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value	0
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Fair Value	0
Debt Securities, Held-to-maturity, Fair Value	67,909,000	68,457,000
Available-for-sale Securities, Amortized Cost Basis	701,225,000	581,543,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	2,310,000	2,900,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	11,261,000	5,864,000
Available-for-sale Securities, Gross Realized Gains	941,000	773,000	1,192,000
Available-for-sale Securities, Gross Realized Losses	40,000	157,000	0
Available-for-sale Securities, Income Tax Expense	261,000	216,000	$ 465,000
U.S. Treasury securities and obligations of U.S. government corporations & agencies
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	148,656,000
After 1 through 5 years	49,993,000
After 5 through 10 years	0
After ten years	0
Fair Value	198,649,000	113,770,000
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost	39,995,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost	29,441,000
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost	0
Debt Securities, Held-to-maturity, Maturity, Allocated and Single Maturity Date, after 10 Years, Amortized Cost	0
Held-to-maturity, at amortized cost (estimated fair value of $67,909 and $68,457 at December 31, 2018 and 2017, respectively)	69,436,000	69,332,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	16,095,000	58,584,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(148,000)	(540,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	105,549,000	47,972,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(3,087,000)	(1,494,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	121,644,000	106,556,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (3,235,000)	$ (2,034,000)
Number of AFS securities in Unrealized Loss Positions | securities	23	11
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 19,683,000	$ 34,101,000
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(147,000)	(525,000)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	48,226,000	14,540,000
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,380,000)	(453,000)
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	67,909,000	48,641,000
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	$ (1,527,000)	$ (978,000)
Number of HTM securities in Unrealized Loss Positions | securities	9	7
Credit losses on trust preferred securities held [Abstract]
Debt Securities, Held-to-maturity, Fair Value	$ 67,909,000	$ 68,457,000
Available-for-sale Securities, Amortized Cost Basis	201,380,000	115,796,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	504,000	8,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	3,235,000	2,034,000
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	103,000
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	1,527,000	978,000
Obligations of states and political subdivisions
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	23,282,000
After 1 through 5 years	89,930,000
After 5 through 10 years	78,294,000
After ten years	1,073,000
Fair Value	192,579,000	166,266,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	38,782,000	42,618,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(450,000)	(769,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	42,741,000	9,267,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(1,390,000)	(256,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	81,523,000	51,885,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (1,840,000)	(1,025,000)
Number of AFS securities in Unrealized Loss Positions | securities	84
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		(39)
Credit losses on trust preferred securities held [Abstract]
Available-for-sale Securities, Amortized Cost Basis	$ 193,195,000	165,037,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,224,000	2,254,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,840,000	1,025,000
Mortgage-backed securities
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	622,000
After 1 through 5 years	160,900,000
After 5 through 10 years	137,150,000
After ten years	0
Fair Value	298,672,000	293,811,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	81,435,000	187,949,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1,150,000)	(1,942,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	171,321,000	22,609,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	(5,036,000)	(518,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	252,756,000	210,558,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (6,186,000)	$ (2,460,000)
Number of AFS securities in Unrealized Loss Positions | securities	69	26
Credit losses on trust preferred securities held [Abstract]
Available-for-sale Securities, Amortized Cost Basis	$ 304,372,000	$ 295,778,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	486,000	493,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	6,186,000	2,460,000
Trust preferred securities
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value		2,548,000
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		2,548,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		(345,000)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,548,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ (345,000)
Number of AFS securities in Unrealized Loss Positions | securities		1
Credit losses on trust preferred securities held [Abstract]
Available-for-sale Securities, Amortized Cost Basis		$ 2,893,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax		0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		345,000
Other securities
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
One year or less	0
After 1 through 5 years	2,010,000
After 5 through 10 years	0
After ten years	364,000
Fair Value	2,374,000	2,184,000
Credit losses on trust preferred securities held [Abstract]
Available-for-sale Securities, Amortized Cost Basis	2,278,000	2,039,000
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	96,000	145,000
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ 0	$ 0