RETIREMENT BENEFIT PLANS, Fair Value of Pension Plan Assets (Details) - USD ($)		12 Months Ended
		Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Equity Securities [Member]
Fair values of pension plans assets [Abstract]
Long-term target allocations for plan assets		50.00%
Fixed income [Member]
Fair values of pension plans assets [Abstract]
Long-term target allocations for plan assets		50.00%
Pension Benefit [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		$ 66,170,875	$ 72,098,772	$ 65,627,499
Number of shares of employer common stock included plan assets (in shares)		0	0
Cash dividends received		$ 95,488	$ 95,488
Pension Benefit [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		5,247,495	5,675,021
Pension Benefit [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		60,923,380	66,423,751
Pension Benefit [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		0	0
Pension Benefit [Member] | Common/Collective Trust Funds [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		306,882	278,016
Pension Benefit [Member] | Common/Collective Trust Funds [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		0	0
Pension Benefit [Member] | Common/Collective Trust Funds [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		306,882	278,016
Pension Benefit [Member] | Common/Collective Trust Funds [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		0	0
Pension Benefit [Member] | Equity Securities [Member]
Fair values of pension plans assets [Abstract]
Value of employer common stock included plan assets		0	0
Pension Benefit [Member] | The Eastern Company Common Stock [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		5,247,495	5,675,021
Pension Benefit [Member] | The Eastern Company Common Stock [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		5,247,495	5,675,021
Pension Benefit [Member] | The Eastern Company Common Stock [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		0	0
Pension Benefit [Member] | The Eastern Company Common Stock [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		0	0
Pension Benefit [Member] | Russell Multi Asset Core Plus Fund [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[1]	30,611,519	31,642,838
Pension Benefit [Member] | Russell Multi Asset Core Plus Fund [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[1]	0	0
Pension Benefit [Member] | Russell Multi Asset Core Plus Fund [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[1]	30,611,519	31,642,838
Pension Benefit [Member] | Russell Multi Asset Core Plus Fund [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[1]	0	0
Pension Benefit [Member] | Russell 8 Year LDI Fixed Income Fund [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[2]	5,735,993	6,033,648
Pension Benefit [Member] | Russell 8 Year LDI Fixed Income Fund [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[2]	0	0
Pension Benefit [Member] | Russell 8 Year LDI Fixed Income Fund [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[2]	5,735,993	6,033,648
Pension Benefit [Member] | Russell 8 Year LDI Fixed Income Fund [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[2]	0	0
Pension Benefit [Member] | Russell 14 Year LDI Fixed Income Fund [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[2]	17,044,596	18,083,206
Pension Benefit [Member] | Russell 14 Year LDI Fixed Income Fund [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[2]	0	0
Pension Benefit [Member] | Russell 14 Year LDI Fixed Income Fund [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[2]	17,044,596	18,083,206
Pension Benefit [Member] | Russell 14 Year LDI Fixed Income Fund [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[2]	0	0
Pension Benefit [Member] | Russell 15 Year STRIPS Fixed Income Fund [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	1,811,436	1,905,068
Pension Benefit [Member] | Russell 15 Year STRIPS Fixed Income Fund [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	0	0
Pension Benefit [Member] | Russell 15 Year STRIPS Fixed Income Fund [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	1,811,436	1,905,068
Pension Benefit [Member] | Russell 15 Year STRIPS Fixed Income Fund [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	0	0
Pension Benefit [Member] | Russell 10 Year STRIPS Fixed Income Fund [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	3,408,879	3,570,427
Pension Benefit [Member] | Russell 10 Year STRIPS Fixed Income Fund [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	0	0
Pension Benefit [Member] | Russell 10 Year STRIPS Fixed Income Fund [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	3,408,879	3,570,427
Pension Benefit [Member] | Russell 10 Year STRIPS Fixed Income Fund [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	0	0
Pension Benefit [Member] | Russell 28 to 29 Year STRIPS Fixed Income Fund [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	2,004,075	2,144,581
Pension Benefit [Member] | Russell 28 to 29 Year STRIPS Fixed Income Fund [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	0	0
Pension Benefit [Member] | Russell 28 to 29 Year STRIPS Fixed Income Fund [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	2,004,075	2,144,581
Pension Benefit [Member] | Russell 28 to 29 Year STRIPS Fixed Income Fund [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets	[3]	$ 0	0
Pension Benefit [Member] | Insurance Contracts [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets			2,765,967
Pension Benefit [Member] | Insurance Contracts [Member] | Level 1 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets			0
Pension Benefit [Member] | Insurance Contracts [Member] | Level 2 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets			2,765,967
Pension Benefit [Member] | Insurance Contracts [Member] | Level 3 [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets			$ 0
Pension Benefit [Member] | Equity Securities, Common Stock [Member]
Fair values of pension plans assets [Abstract]
Number of shares of employer common stock included plan assets (in shares)		217,018	217,018
Value of employer common stock included plan assets		$ 5,247,495	$ 5,675,021
Other Postretirement Benefit [Member]
Fair values of pension plans assets [Abstract]
Fair value of plan assets		$ 1,448,126	$ 1,391,239	$ 1,287,350

[1] The investment objective of the RITC (formerly Russell) Multi-Asset Core Plus Fund seeks to provide long-term growth of capital over a market cycle by offering a diversified portfolio of funds and separate accounts investing in global stock, return seeking fixed income, commodities, global real estate and opportunistic investments. They hold a dynamic mix of underlying Russell Investments funds and/or separate accounts. Russell Investments is a strong proponent of disciplined strategic asset allocation and rebalancing strategies, and believes that unstable movements in the market have the potential to create opportunities. By identifying short-term mispricing, and making small tactical adjustments to the Multi-Asset Core Plus Fund, they believe there is potential to enhance returns while continuing to manage risks.

[2] The Target Duration LDI Fixed Income Funds seek to outperform their respective Barclays-Russell LDI Indexes over a full market cycle. These Funds invest primarily in investment grade corporate bonds that closely match those found in discount curves used to value U.S. pension liabilities. They seek to provide additional incremental return through modest interest rate timing, security selection and tactical use of non-credit sectors. Generally for use in combination with other bond funds to gain additional credit exposure, with the goal of reducing the mismatch between a plan's assets and liabilities.

[3] The STRIPS (Separate Trading of Registered Interest and Principal of Securities) Funds seek to provide duration and Treasury exposure by investing in an optimized subset of the STRIPS universe with a similar duration profile as the Barclays U.S. Treasury STRIPS 10-11 year, 16-16 year or 28-29 year Index. These passively managed funds are generally used with other bond funds to add additional duration to the asset portfolio. This will help reduce the mismatch between a plan's assets and liabilities.