Short-term Borrowings - Additional Information (Details) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Short Term Debt [Line Items]
Borrowings against lines	$ 150,000,000	$ 18,000,000
Pledged investment securities	60,371,000	85,587,000
Federal Reserve Bank \| Borrower in Custody Program
Short Term Debt [Line Items]
Line of credit	765,107,000
Pledged loan securities	1,072,118,000
Federal Home Loan Bank
Short Term Debt [Line Items]
Borrowings against lines	150,000,000	18,000,000
Pledged investment securities	60,371,000	85,587,000
Loans from Federal Home Loan Banks	565,718,000	69,915,000
U.S. Government Agency Securities \| One to Four Family and Multi-Family Mortgages \| Federal Home Loan Bank
Short Term Debt [Line Items]
Line of credit	300,000,000	150,000,000
First Tennessee Bank, N.A
Short Term Debt [Line Items]
Line of credit	$ 30,000,000	30,000,000
Number of consecutive trading days	14 days
Borrowings against lines	$ 0	0
BBVA Compass Bank
Short Term Debt [Line Items]
Line of credit	$ 10,000,000	10,000,000
Number of consecutive trading days	14 days
Borrowings against lines	$ 0	0
SunTrust Bank
Short Term Debt [Line Items]
Line of credit	$ 15,000,000
Number of consecutive trading days	7 days
Borrowings against lines	$ 0	0
SunTrust Bank \| Minimum
Short Term Debt [Line Items]
Marketable security with current value, percent	125.00%
First National Banker's Bank
Short Term Debt [Line Items]
Line of credit	$ 10,000,000
Number of consecutive trading days	30 days
Zions Bank
Short Term Debt [Line Items]
Line of credit	$ 25,000,000
PNC Bank
Short Term Debt [Line Items]
Line of credit	20,000,000
Servis First Bank
Short Term Debt [Line Items]
Line of credit	15,000,000	15,000,000
Borrowings against lines	$ 0	$ 0

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Number of consecutive trading days.

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- Definition

Amount of short term borrowing where a bank borrows, at the federal funds rate, from another bank.

+ References

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- Definition

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The fair value, as of the date of each statement of financial position presented, of loans that are restricted as collateral for the payment of the FHLB debt obligations, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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- Definition

The fair value, as of the date of each statement of financial position presented, of securities which are owned but transferred to serve as collateral for the payment of the FHLB debt obligations, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

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- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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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