XML 70 R59.htm IDEA: XBRL DOCUMENT
v3.25.3

Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Jun. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Income Statement Related Disclosures |  |  |  |  |
Net interest income (expense) | $ 474,695 | $ 440,740 |  | $ 1,388,640 | $ 1,294,583
Provision for (reversal of) credit losses | 21,690 | 23,434 |  | 35,855 | 103,818
Net interest income after provision for (reversal of) credit losses | 453,005 | 417,306 |  | 1,352,785 | 1,190,765
Non-interest revenue: |  |  |  |  |
Service charges on deposit accounts | 26,303 | 23,683 |  | 74,675 | 68,403
Fiduciary and asset management fees | 21,039 | 19,714 |  | 61,288 | 58,455
Card fees | 19,894 | 18,439 |  | 61,253 | 57,343
Brokerage revenue | 21,673 | 20,810 |  | 62,779 | 63,974
Mortgage banking income | 4,374 | 4,033 |  | 12,147 | 11,395
Capital markets income | 13,944 | 10,284 |  | 33,845 | 31,988
Other non-interest revenue | 33,470 | 27,017 |  | 85,310 | (177,541)
Total non-interest revenue | 140,697 | 123,980 |  | 391,297 | 114,017
Non-interest expense: |  |  |  |  |
Salaries and other personnel expense | 197,313 | 184,814 |  | 575,006 | 552,742
Other operating expense | 151,416 | 128,876 |  | 397,458 | 385,490
Total non-interest expense | 348,729 | 313,690 |  | 972,464 | 938,232
Income before income taxes | 244,973 | 227,596 |  | 771,618 | 366,550
Merger-related expense | 23,757 | 0 |  | 23,757 | 0
Investment securities gains (losses), net | 1,742 | 0 |  | 1,742 | (256,660)
Operating Segments | Wholesale Banking |  |  |  |  |
Income Statement Related Disclosures |  |  |  |  |
Net interest income (expense) | 186,300 | 181,596 |  | 539,546 | 546,836
Provision for (reversal of) credit losses | 28,368 | 31,313 |  | 90,683 | 91,616
Net interest income after provision for (reversal of) credit losses | 157,932 | 150,283 |  | 448,863 | 455,220
Non-interest revenue: |  |  |  |  |
Service charges on deposit accounts | 5,943 | 5,399 |  | 17,511 | 15,759
Fiduciary and asset management fees | 0 | 0 |  | 0 | 0
Card fees | 3 | 3 |  | 8 | 8
Brokerage revenue | 0 | 0 |  | 0 | 0
Mortgage banking income | 0 | 0 |  | 0 | 0
Capital markets income | 10,986 | 6,906 |  | 22,034 | 18,271
Other non-interest revenue | 4,948 | 2,637 |  | 11,999 | 8,178
Total non-interest revenue | 21,880 | 14,945 |  | 51,552 | 42,216
Non-interest expense: |  |  |  |  |
Salaries and other personnel expense | 23,474 | 21,514 |  | 72,762 | 69,269
Other operating expense | 8,259 | 9,091 |  | 24,858 | 31,221
Total non-interest expense | 31,733 | 30,605 |  | 97,620 | 100,490
Income before income taxes | 148,079 | 134,623 |  | 402,795 | 396,946
Operating Segments | Community Banking |  |  |  |  |
Income Statement Related Disclosures |  |  |  |  |
Net interest income (expense) | 105,612 | 100,910 |  | 303,784 | 298,030
Provision for (reversal of) credit losses | 11,051 | 10,617 |  | 32,929 | 29,898
Net interest income after provision for (reversal of) credit losses | 94,561 | 90,293 |  | 270,855 | 268,132
Non-interest revenue: |  |  |  |  |
Service charges on deposit accounts | 7,642 | 7,373 |  | 22,654 | 20,823
Fiduciary and asset management fees | 0 | 0 |  | 0 | 0
Card fees | 8,894 | 7,363 |  | 28,005 | 23,612
Brokerage revenue | 0 | 0 |  | 0 | 0
Mortgage banking income | 0 | 0 |  | 0 | 0
Capital markets income | 1,622 | 1,815 |  | 4,253 | 5,306
Other non-interest revenue | 724 | 763 |  | 2,567 | 2,403
Total non-interest revenue | 18,882 | 17,314 |  | 57,479 | 52,144
Non-interest expense: |  |  |  |  |
Salaries and other personnel expense | 26,369 | 25,543 |  | 81,266 | 80,606
Other operating expense | 11,092 | 12,267 |  | 32,918 | 35,983
Total non-interest expense | 37,461 | 37,810 |  | 114,184 | 116,589
Income before income taxes | 75,982 | 69,797 |  | 214,150 | 203,687
Operating Segments | Consumer Banking |  |  |  |  |
Income Statement Related Disclosures |  |  |  |  |
Net interest income (expense) | 136,631 | 136,329 |  | 400,499 | 410,506
Provision for (reversal of) credit losses | 5,248 | 5,263 |  | 15,895 | 15,339
Net interest income after provision for (reversal of) credit losses | 131,383 | 131,066 |  | 384,604 | 395,167
Non-interest revenue: |  |  |  |  |
Service charges on deposit accounts | 12,216 | 10,520 |  | 32,889 | 30,960
Fiduciary and asset management fees | 0 | 0 |  | 0 | 0
Card fees | 6,729 | 6,671 |  | 19,955 | 19,734
Brokerage revenue | 0 | 0 |  | 0 | 0
Mortgage banking income | 0 | 0 |  | 0 | 0
Capital markets income | 0 | 0 |  | 226 | 0
Other non-interest revenue | 1,486 | 1,787 |  | 5,061 | 5,538
Total non-interest revenue | 20,431 | 18,978 |  | 58,131 | 56,232
Non-interest expense: |  |  |  |  |
Salaries and other personnel expense | 31,363 | 30,260 |  | 91,945 | 90,002
Other operating expense | 17,970 | 19,282 |  | 53,787 | 63,351
Total non-interest expense | 49,333 | 49,542 |  | 145,732 | 153,353
Income before income taxes | 102,481 | 100,502 |  | 297,003 | 298,046
Operating Segments | Financial Management Services |  |  |  |  |
Income Statement Related Disclosures |  |  |  |  |
Net interest income (expense) | 21,882 | 26,813 |  | 64,711 | 75,283
Provision for (reversal of) credit losses | 3,995 | 4,082 |  | 12,035 | 11,868
Net interest income after provision for (reversal of) credit losses | 17,887 | 22,731 |  | 52,676 | 63,415
Non-interest revenue: |  |  |  |  |
Service charges on deposit accounts | 4 | 5 |  | 12 | 13
Fiduciary and asset management fees | 21,039 | 19,714 |  | 61,288 | 58,455
Card fees | 0 | 0 |  | 0 | 0
Brokerage revenue | 21,673 | 20,810 |  | 62,779 | 63,974
Mortgage banking income | 4,374 | 4,033 |  | 12,147 | 11,395
Capital markets income | 38 | 0 |  | 342 | 430
Other non-interest revenue | 1,569 | 1,884 |  | 4,973 | 4,888
Total non-interest revenue | 48,697 | 46,446 |  | 141,541 | 139,155
Non-interest expense: |  |  |  |  |
Salaries and other personnel expense | 31,679 | 30,214 |  | 94,423 | 93,772
Other operating expense | 7,807 | 7,727 |  | 23,943 | 22,198
Total non-interest expense | 39,486 | 37,941 |  | 118,366 | 115,970
Income before income taxes | 27,098 | 31,236 |  | 75,851 | 86,600
Treasury and Corporate Other |  |  |  |  |
Income Statement Related Disclosures |  |  |  |  |
Net interest income (expense) | 24,270 | (4,908) |  | 80,100 | (36,072)
Provision for (reversal of) credit losses | (26,972) | (27,841) |  | (115,687) | (44,903)
Net interest income after provision for (reversal of) credit losses | 51,242 | 22,933 |  | 195,787 | 8,831
Non-interest revenue: |  |  |  |  |
Service charges on deposit accounts | 498 | 386 |  | 1,609 | 848
Fiduciary and asset management fees | 0 | 0 |  | 0 | 0
Card fees | 4,268 | 4,402 |  | 13,285 | 13,989
Brokerage revenue | 0 | 0 |  | 0 | 0
Mortgage banking income | 0 | 0 |  | 0 | 0
Capital markets income | 1,298 | 1,563 |  | 6,990 | 7,981
Other non-interest revenue | 24,743 | 19,946 |  | 60,710 | (198,548)
Total non-interest revenue | 30,807 | 26,297 |  | 82,594 | (175,730)
Non-interest expense: |  |  |  |  |
Salaries and other personnel expense | 84,428 | 77,283 |  | 234,610 | 219,093
Other operating expense | 106,288 | 80,509 |  | 261,952 | 232,737
Total non-interest expense | 190,716 | 157,792 |  | 496,562 | 451,830
Income before income taxes | (108,667) | $ (108,562) |  | $ (218,181) | $ (618,729)
Investment securities gains (losses), net |  |  | $ (256,700) |  |
Treasury and Corporate Other | Pinnacle |  |  |  |  |
Non-interest expense: |  |  |  |  |
Merger-related expense | $ 23,800 |  |  |  |

X
- Definition Fees And Commissions, Credit And Debit Card + References No definition available. + Details
Name: | syn_FeesAndCommissionsCreditAndDebitCard
Namespace Prefix: | syn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fees And Commissions, Depositor Accounts1 + References No definition available. + Details
Name: | syn_FeesAndCommissionsDepositorAccounts1
Namespace Prefix: | syn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fees And Commissions, Fiduciary And Trust + References No definition available. + Details
Name: | syn_FeesAndCommissionsFiduciaryAndTrust
Namespace Prefix: | syn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Non-Interest Expense, Other Operating + References No definition available. + Details
Name: | syn_NonInterestExpenseOtherOperating
Namespace Prefix: | syn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Noninterest Income, Mortgage Banking + References No definition available. + Details
Name: | syn_NoninterestIncomeMortgageBanking
Namespace Prefix: | syn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Swap Fee Income + References No definition available. + Details
Name: | syn_SwapFeeIncome
Namespace Prefix: | syn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of commission revenue from buying and selling securities on behalf of customers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_BrokerageCommissionsRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of expense for acquisition-related cost incurred to effect business combination. Includes, but is not limited to, finder's fee; advisory, legal, accounting, valuation, and other professional and consulting fees; and general administrative cost, including cost of maintaining internal acquisition department. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-7 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 25 -Paragraph 23 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479405/805-10-25-23 + Details
Name: | us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of unrealized and realized gain (loss) on investment in debt and equity securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(9)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(7)(c)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 + Details
Name: | us-gaap_DebtAndEquitySecuritiesGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147476148/220-40-50-22 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-4 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 21 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-21 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-14 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 235 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147478671/942-235-S50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-05(b)(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477314/942-235-S99-1 Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-22 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 48 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482785/280-10-55-48 Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-32 Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 30 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-30 Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 270 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482964/270-10-50-1 Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (ee) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-32 Reference 12: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 32 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-32 Reference 13: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(11)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1 Reference 14: http://www.xbrl.org/2003/role/exampleRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 31 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-31 Reference 15: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(10)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 16: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(15)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_IncomeStatementRelatedDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of interest income or expense, including any amortization and accretion (as applicable) of discounts and premiums, including consideration of the provisions for loan, lease, credit, and other related losses. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 21 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-21 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(12)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of interest income (expense) classified as operating. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 21 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-21 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 280 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482810/280-10-50-22 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(10)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_InterestIncomeExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of expense for salary, wage, profit sharing; incentive and equity-based compensation; and other employee benefit. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 21 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-21 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(4)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(14)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_LaborAndRelatedExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Total aggregate amount of all noninterest expense. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 21 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-21 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(14)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_NoninterestExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_NoninterestExpenseAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 21 -Publisher FASB -URI https://asc.fasb.org/1943274/2147476153/220-40-55-21 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_NoninterestIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_NoninterestIncomeAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of revenue earned, classified as other, excluding interest income. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(1)(e)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 + Details
Name: | us-gaap_NoninterestIncomeOtherOperatingIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=syn_WholesaleBankingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=syn_CommunityBankingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=syn_ConsumerBankingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=syn_FinancialManagementServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidationItemsAxis=syn_CorporateAndReconcilingItemsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=syn_PinnacleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |