Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Nov. 04, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Entity Information [Line Items]
Document Transition Report	false
Common Stock, Shares, Outstanding	33,043,812			32,965,692
City Area Code	(781)
Entity Incorporation, State or Country Code	MA
Entity File Number	1-9047
Document Quarterly Report	true
Entity Registrant Name	Independent Bank Corp.
Entity Tax Identification Number	04-2870273
Entity Central Index Key	0000776901
Document Type	10-Q
Document Period End Date	Sep. 30, 2021
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		33,049,880
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Local Phone Number	878-6100
Entity Address, Address Line One	2036 Washington Street,
Entity Address, City or Town	Hanover,
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02339
Entity Shell Company	false
NASDAQ/NGS (GLOBAL SELECT MARKET) [Member]
Entity Information [Line Items]
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	INDB
Common Class A [Member]
Entity Information [Line Items]
Common Stock, Shares, Outstanding	33,043,812		33,037,859	32,965,692	32,955,547	32,942,110	34,377,388
Mailing Address [Member]
Entity Information [Line Items]
Entity Address, Address Line One	288 Union Street,
Entity Address, City or Town	Rockland,
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02370