Loans, Allowance for Loan Losses and Credit Quality (TDR's and Other Pertinent Information) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Summary of Troubled Debt Restructurings and other pertinent information
TDRS ON ACCRUAL STATUS	$ 36,887	$ 38,382
TDRS ON NONACCRUAL	4,899	5,248
TOTAL TDR'S	41,786	43,630
AMOUNT OF SPECIFIC RESERVES INCLUDED IN THE ALLOWANCE FOR LOAN LOSSES ASSOCIATED WITH TDRS:	1,816	2,004
Additional Commitments To Lend To Borrower For Trouble Debt Restructuring	$ 2,071	$ 1,400

Additional commitments to lend to a borrower for trouble debt restructuring.

No definition available.

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Amount of specific reserves included in the allowance for loan losses associated with trouble debt restructuring.

No definition available.

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Financing receivable recorded investment trouble debt restructuring.

No definition available.

Name:	indb_FinancingReceivableRecordedInvestmentTroubleDebtRestructuring
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Data Type:	xbrli:monetaryItemType
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Troubled Debt Restructurings recorded investment that are on accrual status as of the balance sheet date.

No definition available.

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Troubled Debt Restructurings recorded investment that are on nonaccrual status as of the balance sheet date.

No definition available.

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