Fair Value Accounting and Measurement (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Financial Assets And Liabilities Accounted For Fair Value On Recurring Basis

The following table sets forth the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis at December 31, 2017 and 2016 by level within the fair value hierarchy. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement:

	Fair value  at December 31, 2017		Fair Value Measurements at Reporting Date Using
			Level 1		Level 2		Level 3
	(in thousands)
Assets
Securities available for sale
U.S. government agency and sponsored enterprise mortgage-back securities and collateralized mortgage obligations	$	1,726,725	$	—	$	1,726,725	$	—
State and municipal securities	596,004		—		596,004		—
U.S. government agency and government-sponsored enterprise securities	414,774		—		414,774		—
U.S. government securities	248		248		—		—
Other securities	5,080		5,080		—		—
Total securities available for sale	$	2,742,831	$	5,328	$	2,737,503	$	—
Other assets (Interest rate contracts)	$	6,707	$	—	$	6,707	$	—
Liabilities
Other liabilities (Interest rate contracts)	$	6,714	$	—	$	6,714	$	—

	Fair value  at December 31, 2016		Fair Value Measurements at Reporting Date Using
			Level 1		Level 2		Level 3
	(in thousands)
Assets
Securities available for sale
U.S. government agency and sponsored enterprise mortgage-back securities and collateralized mortgage obligations	$	1,465,732	$	—	$	1,465,732	$	—
State and municipal debt securities	475,060		—		475,060		—
U.S. government agency and government-sponsored enterprise securities	331,902		—		331,902		—
U.S. government securities	800		800		—		—
Other securities	5,083		—		5,083		—
Total securities available for sale	$	2,278,577	$	800	$	2,277,777	$	—
Other assets (Interest rate contracts)	$	9,012	$	—	$	9,012	$	—
Liabilities
Other liabilities (Interest rate contracts)	$	9,036	$	—	$	9,036	$	—

Financial Assets Accounted For Fair Value On Nonrecurring Basis

The following table sets forth the Company’s assets that were measured using fair value estimates on a nonrecurring basis during the years ended December 31, 2017 and 2016:

	Fair value  at December 31, 2017		Fair Value Measurements at Reporting Date Using						Losses During the Year Ended December 31, 2017
			Level 1		Level 2		Level 3
	(in thousands)
Impaired loans	$	6,577	$	—	$	—	$	6,577	$	2,507
OREO	1,423		—		—		1,423		239
	$	8,000	$	—	$	—	$	8,000	$	2,746

	Fair value  at December 31, 2016		Fair Value Measurements at Reporting Date Using						Losses During the Year Ended December 31, 2016
			Level 1		Level 2		Level 3
	(in thousands)
Impaired loans	$	3,787	$	—	$	—	$	3,787	$	5,413
OREO	4,388		—		—		4,388		332
	$	8,175	$	—	$	—	$	8,175	$	5,745

Fair Value Inputs, Assets, Quantitative Information [Table Text Block]

The range and weighted-average of the significant unobservable inputs used to fair value our Level 3 nonrecurring assets during 2017 and 2016, along with the valuation techniques used, are shown in the following tables:

	Fair value  at December 31, 2017		Valuation Technique	Unobservable Input	Range (Weighted Average) (1)
	(dollars in thousands)
Impaired loans - collateral-dependent (3)	$	3,519	Fair Market Value of Collateral	Adjustment to Stated Value	N/A (2)
Impaired loans - other	$	3,058	Discounted Cash Flow	Discount Rate	3.75% - 7.75% (4.12%)
OREO	$	1,423	Fair Market Value of Collateral	Adjustment to Appraisal Value	N/A (2)
(1) Discount rate used in discounted cash flow valuation.
(2) Quantitative disclosures are not provided for collateral-dependent impaired loans and OREO because there were no adjustments made to the appraisal values or stated values during the current period.
(3) Collateral consists of real property and a government agency guarantee.

	Fair value  at December 31, 2016		Valuation Technique	Unobservable Input	Range (Weighted Average) (1)
	(dollars in thousands)
Impaired loans - collateral-dependent (3)	$	2,248	Fair Market Value of Collateral	Adjustment to Stated Value	N/A (2)
Impaired loans - other	$	1,539	Discounted Cash Flow	Discount Rate	4.50% - 6.50% (5.26%)
OREO	$	4,388	Fair Market Value of Collateral	Adjustment to Appraisal Value	N/A (2)
(1) Discount rate used in discounted cash flow valuation.
(2) Quantitative disclosures are not provided for collateral-dependent impaired loans and OREO because there were no adjustments made to the appraisal values or stated values during the current period.
(3) Collateral consists of accounts receivable, inventory, equipment and real property.

Fair Value, by Balance Sheet Grouping

The following tables summarize carrying amounts and estimated fair values of selected financial instruments for the periods indicated:

	December 31, 2017
	Carrying Amount		Fair Value		Level 1		Level 2		Level 3
	(in thousands)
Assets
Cash and due from banks	$	244,615	$	244,615	$	244,615	$	—	$	—
Interest-earning deposits with banks	97,918		97,918		97,918		—		—
Securities available for sale	2,742,831		2,742,831		5,328		2,737,503		—
FHLB stock	10,440		10,440		—		10,440		—
Loans held for sale	5,766		5,766		—		5,766		—
Loans	8,283,011		8,055,817		—		—		8,055,817
Interest rate contracts	6,707		6,707		—		6,707		—
Liabilities
Deposits	$	10,532,085	$	10,524,135	$	10,041,040	$	483,095	$	—
FHLB advances	11,579		12,281		—		12,281		—
Repurchase agreements	79,059		79,070		—		79,070		—
Subordinated debentures	35,647		35,895		—		35,895		—
Junior subordinated debentures	8,248		8,248		—		8,248		—
Interest rate contracts	6,714		6,714		—		6,714		—

	December 31, 2016
	Carrying Amount		Fair Value		Level 1		Level 2		Level 3
	(in thousands)
Assets
Cash and due from banks	$	193,038	$	193,038	$	193,038	$	—	$	—
Interest-earning deposits with banks	31,200		31,200		31,200		—		—
Securities available for sale	2,278,577		2,278,577		800		2,277,777		—
FHLB stock	10,240		10,240		—		10,240		—
Loans held for sale	5,846		5,846		—		5,846		—
Loans	6,143,380		6,040,439		—		—		6,040,439
FDIC loss-sharing asset	3,535		867		—		—		867
Interest rate contracts	9,012		9,012		—		9,012		—
Liabilities
Deposits	$	8,059,415	$	8,055,168	$	7,653,122	$	402,046	$	—
FHLB advances	6,493		7,070		—		7,070		—
Repurchase agreements	80,822		81,131		—		81,131		—
Interest rate contracts	9,036		9,036		—		9,036		—