Shareholders' Equity (Tables)

6 Months Ended

Jun. 30, 2022

Equity [Abstract]

Schedule of Minimum Capital Requirements Considered Well Capitalized by FRB and FDIC

As of June 30, 2022 and December 31, 2021, the Company and the Bank met all applicable minimum capital requirements and were considered “well-capitalized” by both the Federal Reserve Bank (“FRB”) and the Federal Deposit Insurance Corporation (“FDIC”).

	Actual					Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer					Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions
	Amount		Ratio			Amount		Ratio			Amount		Ratio
	(dollars in thousands)
At June 30, 2022
Cambridge Bancorp:
Total capital (to risk-weighted assets)	$	438,979		13.4	%	$	344,617		10.5	%	N/A		N/A
Tier 1 capital (to risk-weighted assets)		403,484		12.3	%		278,976		8.5	%	N/A		N/A
Common equity tier I capital (to risk-weighted assets)		403,484		12.3	%		229,745		7.0	%	N/A		N/A
Tier 1 capital (to average assets)		403,484		8.1	%		199,142		4.0	%	N/A		N/A
Cambridge Trust Company:
Total capital (to risk-weighted assets)	$	422,899		12.9	%	$	344,585		10.5	%	$	328,176		10.0	%
Tier 1 capital (to risk-weighted assets)		387,404		11.8	%		278,950		8.5	%		262,541		8.0	%
Common equity tier I capital (to risk-weighted assets)		387,404		11.8	%		229,723		7.0	%		213,314		6.5	%
Tier 1 capital (to average assets)		387,404		7.8	%		199,131		4.0	%		248,913		5.0	%

	Actual					Minimum Capital Required For Capital Adequacy Plus Capital Conservation Buffer					Minimum To Be Well-Capitalized Under Prompt Corrective Action Provisions
	Amount		Ratio			Amount		Ratio			Amount		Ratio
	(dollars in thousands)
At December 31, 2021
Cambridge Bancorp:
Total capital (to risk-weighted assets)	$	420,398		13.6	%	$	325,617		10.5	%	N/A		N/A
Tier 1 capital (to risk-weighted assets)		384,518		12.4	%		263,595		8.5	%	N/A		N/A
Common equity tier I capital (to risk-weighted assets)		384,518		12.4	%		217,078		7.0	%	N/A		N/A
Tier 1 capital (to average assets)		384,518		8.3	%		185,015		4.0	%	N/A		N/A
Cambridge Trust Company:
Total capital (to risk-weighted assets)	$	409,806		13.2	%	$	325,587		10.5	%	$	310,082		10.0	%
Tier 1 capital (to risk-weighted assets)		373,926		12.1	%		263,570		8.5	%		248,066		8.0	%
Common equity tier I capital (to risk-weighted assets)		373,926		12.1	%		217,058		7.0	%		201,554		6.5	%
Tier 1 capital (to average assets)		373,926		8.1	%		185,003		4.0	%		231,254		5.0	%