3.10.0.1 html 306 374 1 false 85 0 false 6 false false R1.htm 100000 - Document - Document and Entity Information Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DocumentDocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 100010 - Statement - CONSOLIDATED BALANCE SHEETS (UNAUDITED) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/StatementCONSOLIDATEDBALANCESHEETSUNAUDITED CONSOLIDATED BALANCE SHEETS (UNAUDITED) Statements 2 false false R3.htm 100020 - Statement - CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/StatementCONSOLIDATEDBALANCESHEETSUNAUDITEDParenthetical CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) Statements 3 false false R4.htm 100030 - Statement - CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/StatementCONSOLIDATEDSTATEMENTSOFINCOMEUNAUDITED CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) Statements 4 false false R5.htm 100040 - Statement - UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/StatementUNAUDITEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Statements 5 false false R6.htm 100050 - Statement - UNAUDITED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/StatementUNAUDITEDCONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITY UNAUDITED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY Statements 6 false false R7.htm 100060 - Statement - UNAUDITED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY (Parenthetical) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/StatementUNAUDITEDCONSOLIDATEDSTATEMENTSOFCHANGESINSHAREHOLDERSEQUITYParenthetical UNAUDITED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS EQUITY (Parenthetical) Statements 7 false false R8.htm 100070 - Statement - UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/StatementUNAUDITEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS Statements 8 false false R9.htm 100080 - Disclosure - Basis of Presentation Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureBasisOfPresentation Basis of Presentation Notes 9 false false R10.htm 100090 - Disclosure - Use of Estimates Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureUseOfEstimates Use of Estimates Notes 10 false false R11.htm 100100 - Disclosure - Subsequent Events Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureSubsequentEvents Subsequent Events Notes 11 false false R12.htm 100110 - Disclosure - Recently Issued and Adopted Accounting Guidance Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureRecentlyIssuedAndAdoptedAccountingGuidance Recently Issued and Adopted Accounting Guidance Notes 12 false false R13.htm 100120 - Disclosure - Cash and Cash Equivalents Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureCashAndCashEquivalents Cash and Cash Equivalents Notes 13 false false R14.htm 100130 - Disclosure - Investment Securities Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureInvestmentSecurities Investment Securities Notes 14 false false R15.htm 100140 - Disclosure - Loans and the Allowance for Loan Losses Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLosses Loans and the Allowance for Loan Losses Notes 15 false false R16.htm 100150 - Disclosure - Income Taxes Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureIncomeTaxes Income Taxes Notes 16 false false R17.htm 100160 - Disclosure - Pension and Retirement Plans Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosurePensionAndRetirementPlans Pension and Retirement Plans Notes 17 false false R18.htm 100170 - Disclosure - Stock Based Compensation Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureStockBasedCompensation Stock Based Compensation Notes 18 false false R19.htm 100180 - Disclosure - Financial Instruments with Off-Balance-Sheet Risk Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFinancialInstrumentsWithOffBalanceSheetRisk Financial Instruments with Off-Balance-Sheet Risk Notes 19 false false R20.htm 100190 - Disclosure - Shareholders' Equity Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureShareholdersEquity Shareholders' Equity Notes 20 false false R21.htm 100200 - Disclosure - Other Comprehensive Income Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureOtherComprehensiveIncome Other Comprehensive Income Notes 21 false false R22.htm 100210 - Disclosure - Earnings Per Share Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureEarningsPerShare Earnings Per Share Notes 22 false false R23.htm 100220 - Disclosure - Derivative Financial Instruments Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureDerivativeFinancialInstruments Derivative Financial Instruments Notes 23 false false R24.htm 100230 - Disclosure - Fair Value Measurements Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFairValueMeasurements Fair Value Measurements Notes 24 false false R25.htm 100240 - Disclosure - Basis of Presentation (Policies) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureBasisOfPresentationPolicies Basis of Presentation (Policies) Policies http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureRecentlyIssuedAndAdoptedAccountingGuidance 25 false false R26.htm 100250 - Disclosure - Investment Securities (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesTables Investment Securities (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureInvestmentSecurities 26 false false R27.htm 100260 - Disclosure - Loans and the Allowance for Loan Losses (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesTables Loans and the Allowance for Loan Losses (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLosses 27 false false R28.htm 100270 - Disclosure - Income Taxes (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureIncomeTaxesTables Income Taxes (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureIncomeTaxes 28 false false R29.htm 100280 - Disclosure - Pension and Retirement Plans (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosurePensionAndRetirementPlansTables Pension and Retirement Plans (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosurePensionAndRetirementPlans 29 false false R30.htm 100290 - Disclosure - Stock Based Compensation (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureStockBasedCompensationTables Stock Based Compensation (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureStockBasedCompensation 30 false false R31.htm 100300 - Disclosure - Financial Instruments with Off-Balance-Sheet Risk (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFinancialInstrumentsWithOffBalanceSheetRiskTables Financial Instruments with Off-Balance-Sheet Risk (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFinancialInstrumentsWithOffBalanceSheetRisk 31 false false R32.htm 100310 - Disclosure - Shareholders' Equity (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureShareholdersEquityTables Shareholders' Equity (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureShareholdersEquity 32 false false R33.htm 100320 - Disclosure - Other Comprehensive Income (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureOtherComprehensiveIncomeTables Other Comprehensive Income (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureOtherComprehensiveIncome 33 false false R34.htm 100330 - Disclosure - Earnings Per Share (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureEarningsPerShareTables Earnings Per Share (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureEarningsPerShare 34 false false R35.htm 100340 - Disclosure - Derivative Financial Instruments (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureDerivativeFinancialInstrumentsTables Derivative Financial Instruments (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureDerivativeFinancialInstruments 35 false false R36.htm 100350 - Disclosure - Fair Value Measurements (Tables) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsTables Fair Value Measurements (Tables) Tables http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFairValueMeasurements 36 false false R37.htm 100360 - Disclosure - Recently Issued and Adopted Accounting Guidance - Additional Information (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureRecentlyIssuedAndAdoptedAccountingGuidanceAdditionalInformationDetails Recently Issued and Adopted Accounting Guidance - Additional Information (Details) Details 37 false false R38.htm 100370 - Disclosure - Cash and Cash Equivalents - Additional Information (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureCashAndCashEquivalentsAdditionalInformationDetails Cash and Cash Equivalents - Additional Information (Details) Details 38 false false R39.htm 100380 - Disclosure - Investment Securities - Summary of Carrying Amounts of Securities and Their Estimated Fair Values (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesSummaryOfCarryingAmountsOfSecuritiesAndTheirEstimatedFairValuesDetails Investment Securities - Summary of Carrying Amounts of Securities and Their Estimated Fair Values (Details) Details 39 false false R40.htm 100390 - Disclosure - Investment Securities - Gross Unrealized Losses of Aggregated by Investment Category and Length of Time that Individual Securities have been in Continuous Loss Position (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesGrossUnrealizedLossesOfAggregatedByInvestmentCategoryAndLengthOfTimeThatIndividualSecuritiesHaveBeenInContinuousLossPositionDetails Investment Securities - Gross Unrealized Losses of Aggregated by Investment Category and Length of Time that Individual Securities have been in Continuous Loss Position (Details) Details 40 false false R41.htm 100400 - Disclosure - Investment Securities - Additional Information (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesAdditionalInformationDetails Investment Securities - Additional Information (Details) Details 41 false false R42.htm 100410 - Disclosure - Investment Securities - Schedule of Amortized Cost and Fair Value of Debt Securities, Aggregated By Earlier of Guaranteed Call Date or Contractual Maturity (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesScheduleOfAmortizedCostAndFairValueOfDebtSecuritiesAggregatedByEarlierOfGuaranteedCallDateOrContractualMaturityDetails Investment Securities - Schedule of Amortized Cost and Fair Value of Debt Securities, Aggregated By Earlier of Guaranteed Call Date or Contractual Maturity (Details) Details 42 false false R43.htm 100420 - Disclosure - Investment Securities - Summary of Gains (Losses) from Sale of Investment Securities (Detail) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureInvestmentSecuritiesSummaryOfGainsLossesFromSaleOfInvestmentSecuritiesDetail Investment Securities - Summary of Gains (Losses) from Sale of Investment Securities (Detail) Details 43 false false R44.htm 100430 - Disclosure - Loans and the Allowance for Loan Losses - Loans Outstanding by Category (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesLoansOutstandingByCategoryDetails Loans and the Allowance for Loan Losses - Loans Outstanding by Category (Details) Details 44 false false R45.htm 100440 - Disclosure - Loans and the Allowance for Loan Losses - Additional Information (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesAdditionalInformationDetails Loans and the Allowance for Loan Losses - Additional Information (Details) Details 45 false false R46.htm 100450 - Disclosure - Loans and the Allowance for Loan Losses - Non-performing Loans Disaggregated by Loan Category (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesNonPerformingLoansDisaggregatedByLoanCategoryDetails Loans and the Allowance for Loan Losses - Non-performing Loans Disaggregated by Loan Category (Details) Details 46 false false R47.htm 100460 - Disclosure - Loans and the Allowance for Loan Losses - Loans Receivable Disaggregated by Credit Quality Indicator (Detail) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesLoansReceivableDisaggregatedByCreditQualityIndicatorDetail Loans and the Allowance for Loan Losses - Loans Receivable Disaggregated by Credit Quality Indicator (Detail) Details 47 false false R48.htm 100470 - Disclosure - Loans and the Allowance for Loan Losses - Schedule of Loans Receivable Disaggregated by Past Due Status (Detail) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesScheduleOfLoansReceivableDisaggregatedByPastDueStatusDetail Loans and the Allowance for Loan Losses - Schedule of Loans Receivable Disaggregated by Past Due Status (Detail) Details 48 false false R49.htm 100480 - Disclosure - Loans and the Allowance for Loan Losses - Information Pertaining to Impaired Loans (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesInformationPertainingToImpairedLoansDetails Loans and the Allowance for Loan Losses - Information Pertaining to Impaired Loans (Details) Details 49 false false R50.htm 100490 - Disclosure - Loans and the Allowance for Loan Losses - Summary of Changes in Allowance for Loan Losses Disaggregated by Loan Type (Detail) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesSummaryOfChangesInAllowanceForLoanLossesDisaggregatedByLoanTypeDetail Loans and the Allowance for Loan Losses - Summary of Changes in Allowance for Loan Losses Disaggregated by Loan Type (Detail) Details 50 false false R51.htm 100500 - Disclosure - Loans and the Allowance for Loan Losses - Summary of Allowance for Loan Losses and Related Loans Receivable Disaggregated by Impairment Method (Detail) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureLoansAndAllowanceForLoanLossesSummaryOfAllowanceForLoanLossesAndRelatedLoansReceivableDisaggregatedByImpairmentMethodDetail Loans and the Allowance for Loan Losses - Summary of Allowance for Loan Losses and Related Loans Receivable Disaggregated by Impairment Method (Detail) Details 51 false false R52.htm 100510 - Disclosure - Income Taxes - Additional Information (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetails Income Taxes - Additional Information (Details) Details 52 false false R53.htm 100520 - Disclosure - Income Taxes - Components of Income Tax Expense (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureIncomeTaxesComponentsOfIncomeTaxExpenseDetails Income Taxes - Components of Income Tax Expense (Details) Details 53 false false R54.htm 100530 - Disclosure - Pension and Retirement Plans - Components of Net Periodic Benefit Cost (Credit) (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosurePensionAndRetirementPlansComponentsOfNetPeriodicBenefitCostCreditDetails Pension and Retirement Plans - Components of Net Periodic Benefit Cost (Credit) (Details) Details 54 false false R55.htm 100540 - Disclosure - Pension and Retirement Plans - Additional Information (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosurePensionAndRetirementPlansAdditionalInformationDetails Pension and Retirement Plans - Additional Information (Details) Details 55 false false R56.htm 100550 - Disclosure - Stock Based Compensation - Schedule of Pre-tax Expense Associated with All Outstanding Non-vested Restricted Stock Awards, Restricted Stock Units, Performance Based Restricted Stock Units and Related Tax Benefits (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureStockBasedCompensationScheduleOfPreTaxExpenseAssociatedWithAllOutstandingNonVestedRestrictedStockAwardsRestrictedStockUnitsPerformanceBasedRestrictedStockUnitsAndRelatedTaxBenefitsDetails Stock Based Compensation - Schedule of Pre-tax Expense Associated with All Outstanding Non-vested Restricted Stock Awards, Restricted Stock Units, Performance Based Restricted Stock Units and Related Tax Benefits (Details) Details 56 false false R57.htm 100560 - Disclosure - Financial Instruments with Off-Balance-Sheet Risk - Summary of Off-Balance-Sheet Financial Instruments with Contractual Amounts Include Present Credit Risk (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFinancialInstrumentsWithOffBalanceSheetRiskSummaryOfOffBalanceSheetFinancialInstrumentsWithContractualAmountsIncludePresentCreditRiskDetails Financial Instruments with Off-Balance-Sheet Risk - Summary of Off-Balance-Sheet Financial Instruments with Contractual Amounts Include Present Credit Risk (Details) Details 57 false false R58.htm 100570 - Disclosure - Shareholders' Equity - Minimum Capital Requirements were Considered Well Capitalized by FRB and FDIC (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureShareholdersEquityMinimumCapitalRequirementsWereConsideredWellCapitalizedByFRBAndFDICDetails Shareholders' Equity - Minimum Capital Requirements were Considered Well Capitalized by FRB and FDIC (Details) Details 58 false false R59.htm 100580 - Disclosure - Other Comprehensive Income - Summary of Other Comprehensive Income (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureOtherComprehensiveIncomeSummaryOfOtherComprehensiveIncomeDetails Other Comprehensive Income - Summary of Other Comprehensive Income (Details) Details 59 false false R60.htm 100590 - Disclosure - Other Comprehensive Income - Summary of Reclassifications out of Accumulated Other Comprehensive Income ("AOCI") (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureOtherComprehensiveIncomeSummaryOfReclassificationsOutOfAccumulatedOtherComprehensiveIncomeAOCIDetails Other Comprehensive Income - Summary of Reclassifications out of Accumulated Other Comprehensive Income ("AOCI") (Details) Details 60 false false R61.htm 100600 - Disclosure - Earnings Per Share - Summary of Reconciliation Between Basic and Diluted Earnings Per Share (Detail) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureEarningsPerShareSummaryOfReconciliationBetweenBasicAndDilutedEarningsPerShareDetail Earnings Per Share - Summary of Reconciliation Between Basic and Diluted Earnings Per Share (Detail) Details 61 false false R62.htm 100610 - Disclosure - Derivative Financial Instruments - Additional Information (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureDerivativeFinancialInstrumentsAdditionalInformationDetails Derivative Financial Instruments - Additional Information (Details) Details 62 false false R63.htm 100620 - Disclosure - Derivative Financial Instruments - Summary of Fair Values of Derivative Instruments in the Company's Unaudited Consolidated Balance Sheets (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureDerivativeFinancialInstrumentsSummaryOfFairValuesOfDerivativeInstrumentsInCompanySUnauditedConsolidatedBalanceSheetsDetails Derivative Financial Instruments - Summary of Fair Values of Derivative Instruments in the Company's Unaudited Consolidated Balance Sheets (Details) Details 63 false false R64.htm 100630 - Disclosure - Fair Value Measurements - Summary of Carrying Values and Estimated Fair Values of Financial Instruments (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsSummaryOfCarryingValuesAndEstimatedFairValuesOfFinancialInstrumentsDetails Fair Value Measurements - Summary of Carrying Values and Estimated Fair Values of Financial Instruments (Details) Details 64 false false R65.htm 100640 - Disclosure - Fair Value Measurements - Summary of Certain Assets Reported at Fair Value on a Recurring Basis (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsSummaryOfCertainAssetsReportedAtFairValueOnRecurringBasisDetails Fair Value Measurements - Summary of Certain Assets Reported at Fair Value on a Recurring Basis (Details) Details 65 false false R66.htm 100650 - Disclosure - Fair Value Measurements - Schedule of Carrying Value of Assets Measured at Fair Value on a Non-Recurring Basis (Details) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfCarryingValueOfAssetsMeasuredAtFairValueOnNonRecurringBasisDetails Fair Value Measurements - Schedule of Carrying Value of Assets Measured at Fair Value on a Non-Recurring Basis (Details) Details 66 false false R67.htm 100660 - Disclosure - Fair Value Measurements - Additional Information (Detail) Sheet http://www.cambridgetrust.com/20180630/taxonomy/role/DisclosureFairValueMeasurementsAdditionalInformationDetail Fair Value Measurements - Additional Information (Detail) Details 67 false false All Reports Book All Reports catc-20180630.xml catc-20180630.xsd catc-20180630_cal.xml catc-20180630_def.xml catc-20180630_lab.xml catc-20180630_pre.xml http://xbrl.sec.gov/dei/2018-01-31 http://fasb.org/srt/2018-01-31 http://xbrl.sec.gov/invest/2013-01-31 http://xbrl.sec.gov/stpr/2018-01-31 http://fasb.org/us-gaap/2018-01-31 true true