Commitments and Contingencies	12 Months Ended
Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES To meet the financing needs of its customers, BancShares and its subsidiaries have financial instruments with off-balance sheet risk. These financial instruments include commitments to extend credit, standby letters of credit and recourse obligations on mortgage loans sold. These instruments involve elements of credit, interest rate or liquidity risk. Commitments to extend credit are legally binding agreements to lend to customers. Commitments generally have fixed expiration dates or other termination clauses and may require payment of fees. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future liquidity requirements. Established credit standards control the credit risk exposure associated with these commitments. In some cases, BancShares requires that collateral be pledged to secure the commitment, including cash deposits, securities and other assets. At December 31, 2016, BancShares had unused commitments to extend credit that were $8.81 billion, compared to $7.95 billion at December 31, 2015. Total unfunded commitments relating to investments in affordable housing projects were $57.1 million and $41.8 million at December 31, 2016 and December 31, 2015, respectively, and are included in other liabilities on BancShares' Consolidated Balance Sheet. Standby letters of credit are commitments guaranteeing performance of a customer to a third party. Those commitments are primarily issued to support public and private borrowing arrangements, and the fair value of those commitments is not material. To mitigate its risk, BancShares’ credit policies govern the issuance of standby letters of credit. At December 31, 2016 and 2015, BancShares had standby letters of credit amounting to $83.8 million and $77.9 million, respectively. The credit risk related to the issuance of these letters of credit is essentially the same as that involved in extending loans to clients and, therefore, these letters of credit are collateralized when necessary. Pursuant to standard representations and warranties relating to residential mortgage loan sales sold on a non-recourse basis, contingent obligations exist for various events that may occur following the loan sale. If underwriting or documentation deficiencies are discovered at any point in the life of the loan or if the loan fails to perform per the terms of the loan purchase agreement, typically within 180 days from the date of sale, the investor may require BancShares to repurchase the loan or to repay a portion of the sale proceeds. Other liabilities included reserves of $3.0 million as of December 31, 2016 and 2015 for estimated losses arising from these standard representation and warranty provisions. BancShares has recorded a receivable from the FDIC totaling $4.2 million and $4.1 million as of December 31, 2016 and 2015, respectively, for the expected reimbursement of losses on assets covered under the various shared-loss agreements. The shared-loss agreements are subject to interpretation by both the FDIC and BancShares, and disagreements may arise regarding coverage of losses, expenses and contingencies and requests for reimbursement may be delayed or disallowed for noncompliance. See Note H for additional information on the receivable from the FDIC regarding the early termination of five shared-loss agreements during 2016. The shared-loss agreements for two FDIC-assisted transactions include provisions related to payments that may be owed to the FDIC at the termination of the agreements (clawback liability).The clawback liability represents a payment by BancShares to the FDIC if actual cumulative losses on acquired covered assets are lower than the cumulative losses originally estimated by the FDIC at the time of acquisition. The clawback liability is estimated by discounting estimated future payments and is recorded in the Consolidated Balance Sheets as a payable to the FDIC under the relevant shared-loss agreements. As of December 31, 2016 and 2015, the clawback liability was $97.0 million and $126.5 million, respectively. See Note H for additional information on the clawback liability regarding the early termination of five shared-loss agreements during 2016. BancShares entered into forward-starting advances with the FHLB of Atlanta in June 2016 to receive $200.0 million of fixed rate long-term funding. There are two advances of $100.0 million each scheduled to fund in June 2018 with maturity dates of June 2026 and 2028. BancShares and various subsidiaries have been named as defendants in legal actions arising from their normal business activities in which damages in various amounts are claimed. BancShares is also exposed to litigation risk relating to the prior business activities of banks from which assets were acquired and liabilities assumed in the various merger transactions. Although the amount of any ultimate liability with respect to such matters cannot be determined, in the opinion of management, any such liability will not have a material effect on BancShares’ consolidated financial statements.

COMMITMENTS AND CONTINGENCIES

To meet the financing needs of its customers, BancShares and its subsidiaries have financial instruments with off-balance sheet risk. These financial instruments include commitments to extend credit, standby letters of credit and recourse obligations on mortgage loans sold. These instruments involve elements of credit, interest rate or liquidity risk.

Commitments to extend credit are legally binding agreements to lend to customers. Commitments generally have fixed expiration dates or other termination clauses and may require payment of fees. Since many of the commitments are expected to expire without being drawn upon, the total commitment amounts do not necessarily represent future liquidity requirements. Established credit standards control the credit risk exposure associated with these commitments. In some cases, BancShares requires that collateral be pledged to secure the commitment, including cash deposits, securities and other assets. At December 31, 2016, BancShares had unused commitments to extend credit that were $8.81 billion, compared to $7.95 billion at December 31, 2015. Total unfunded commitments relating to investments in affordable housing projects were $57.1 million and $41.8 million at December 31, 2016 and December 31, 2015, respectively, and are included in other liabilities on BancShares' Consolidated Balance Sheet.

Standby letters of credit are commitments guaranteeing performance of a customer to a third party. Those commitments are primarily issued to support public and private borrowing arrangements, and the fair value of those commitments is not material. To mitigate its risk, BancShares’ credit policies govern the issuance of standby letters of credit. At December 31, 2016 and 2015, BancShares had standby letters of credit amounting to $83.8 million and $77.9 million, respectively. The credit risk related to the issuance of these letters of credit is essentially the same as that involved in extending loans to clients and, therefore, these letters of credit are collateralized when necessary.

Pursuant to standard representations and warranties relating to residential mortgage loan sales sold on a non-recourse basis, contingent obligations exist for various events that may occur following the loan sale. If underwriting or documentation deficiencies are discovered at any point in the life of the loan or if the loan fails to perform per the terms of the loan purchase agreement, typically within 180 days from the date of sale, the investor may require BancShares to repurchase the loan or to repay a portion of the sale proceeds. Other liabilities included reserves of $3.0 million as of December 31, 2016 and 2015 for estimated losses arising from these standard representation and warranty provisions.

BancShares has recorded a receivable from the FDIC totaling $4.2 million and $4.1 million as of December 31, 2016 and 2015, respectively, for the expected reimbursement of losses on assets covered under the various shared-loss agreements. The shared-loss agreements are subject to interpretation by both the FDIC and BancShares, and disagreements may arise regarding coverage of losses, expenses and contingencies and requests for reimbursement may be delayed or disallowed for noncompliance. See Note H for additional information on the receivable from the FDIC regarding the early termination of five shared-loss agreements during 2016.

The shared-loss agreements for two FDIC-assisted transactions include provisions related to payments that may be owed to the FDIC at the termination of the agreements (clawback liability).The clawback liability represents a payment by BancShares to the FDIC if actual cumulative losses on acquired covered assets are lower than the cumulative losses originally estimated by the FDIC at the time of acquisition. The clawback liability is estimated by discounting estimated future payments and is recorded in the Consolidated Balance Sheets as a payable to the FDIC under the relevant shared-loss agreements. As of December 31, 2016 and 2015, the clawback liability was $97.0 million and $126.5 million, respectively. See Note H for additional information on the clawback liability regarding the early termination of five shared-loss agreements during 2016.

BancShares entered into forward-starting advances with the FHLB of Atlanta in June 2016 to receive $200.0 million of fixed rate long-term funding. There are two advances of $100.0 million each scheduled to fund in June 2018 with maturity dates of June 2026 and 2028.

BancShares and various subsidiaries have been named as defendants in legal actions arising from their normal business activities in which damages in various amounts are claimed. BancShares is also exposed to litigation risk relating to the prior business activities of banks from which assets were acquired and liabilities assumed in the various merger transactions. Although the amount of any ultimate liability with respect to such matters cannot be determined, in the opinion of management, any such liability will not have a material effect on BancShares’ consolidated financial statements.