Loans and Loans Held for Sale - Additional Information (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, net of deferred income		$ 5,200	$ 3,200
Unamortized discount related to purchase accounting fair value adjustments		7,100	10,900
Loans		5,615,212	5,062,933
Portfolio loans, net of unearned income		5,611,419	$ 5,027,612
Decrease in loans held-for-sale during period		$ 31,500
Number of loan modified \| loan		18
Number of commitments to lend additional funds on TDRs \| loan		1
Commitment to lend additional funds on TDRs		$ 800
Number of TDRs returned back to accruing status \| loan		5	8
Financial receivable trouble debt restructuring reclassified to accruing trouble debt restructuring status		$ 900	$ 400
Minimum period of loan payment defaults following restructure for TDRs to be in default		90 days
Number of defaulted TDRs that were restructured withing twelve months prior to defaulting \| loan		0	0
Increase in nonperforming assets		$ 7,600
Nonperforming assets		$ 43,314	$ 35,736
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of commercial loans in total portfolio loans		78.00%	76.00%
Loans and leases receivable, gross		$ 4,355,395	$ 3,836,877
Portfolio loans, net of unearned income		4,355,395	3,836,877
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		2,498,476	2,166,603
Portfolio loans, net of unearned income		$ 2,498,476	2,166,603
Number of loan modified \| loan		3
Loans modified not considered to be troubled debt restructuring		$ 3,100
Commercial Real Estate \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross		2,498,476	2,166,603
Portfolio loans, net of unearned income		2,498,476	2,166,603
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		1,401,035	1,256,830
Portfolio loans, net of unearned income		$ 1,401,035	1,256,830
Number of loan modified \| loan		15
Loans modified not considered to be troubled debt restructuring		$ 25,600
Commercial and Industrial \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross		1,401,035	1,256,830
Portfolio loans, net of unearned income		1,401,035	1,256,830
Commercial Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		455,884	413,444
Portfolio loans, net of unearned income		455,884	413,444
Commercial Construction \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross		455,884	413,444
Portfolio loans, net of unearned income		455,884	413,444
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		701,982	639,372
Portfolio loans, net of unearned income		1,190,172	1,116,796
Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		482,284	470,845
Installment and Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Decrease in loans held-for-sale during period	$ (25,000)
Gain on sale of credit card portfolio			2,100
Consumer Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 5,906	$ 6,579
CRE and Commercial Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Out-of-state exposure of combined portfolio		5.20%	5.80%
Percentage of total loans out-of-state		2.70%	3.00%
CRE and Commercial Construction \| Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable, gross		$ 3,000,000
Combined percentage of commercial real estate and commercial construction in total commercial loans		68.00%	67.00%
Combined percentage of commercial real estate and commercial construction in total portfolio loans		53.00%	51.00%
Portfolio loans, net of unearned income			$ 2,600,000
Concentration risk percentage		0.00%	0.00%
Maximum concentration of commercial real estate and commercial construction portfolio in loans		7.00%	7.00%
Integrity Bancshares, Inc.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 543,300	$ 673,300
Nonperforming assets, assumed in business acquisitions		16,900
Integrity Bancshares, Inc. \| Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		273,000	293,200
Integrity Bancshares, Inc. \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		140,800	167,700
Integrity Bancshares, Inc. \| Commercial Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		33,500	69,200
Integrity Bancshares, Inc. \| Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		74,000	115,600
Integrity Bancshares, Inc. \| Home Equity, Installment and Other Consumer Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 22,000	$ 27,500

Combined percentage of commercial real estate and commercial construction in commercial loans.

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Combined percentage of commercial real estate and commercial construction in portfolio loans.

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Commitment to lend additional funds.

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Financial receivable trouble debt restructuring reclassified to accruing trouble debt restructuring status.

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Increase (Decrease) in Net Nonperforming Assets

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Loans modified not considered to be troubled debt restructuring.

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Maximum concentration of commercial real estate and commercial construction portfolio in loans.

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Net Loans Out Of State, Percentage

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Net nonperforming assets.

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Net Nonperforming Assets, Assumed in Business Acquisitions

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Number Of Loans Modified Not Considered To Be Troubled Debt Restructuring

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Number of troubled debt restructuring loans returned back to accruing status.

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Number of Commitment To Lend Additional Funds

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Number of Defaulted Troubled Debt Restructuring Loans Restructured Whiting Twelve Months Prior to Defaulting

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Out of state exposure of combined portfolio.

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Percentage of commercial loans in portfolio loans.

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Period of loans in default treated as troubled debt restructuring.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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The net gain (loss) resulting from a sale of loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes.

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Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount, after allowance for bad debt, of increase (decrease) in loan receivables held-for-sale that are not part of a disposal group.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

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