LEASES - Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets and Liabilities, Lessee [Abstract]
Operating Lease - ROU	$ 5,838	$ 7,338
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	bcpc:OperatingLeaseAndFinanceLeaseRightOfUseAsset	bcpc:OperatingLeaseAndFinanceLeaseRightOfUseAsset
Finance Leases - ROU	$ 2,572	$ 0
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	bcpc:OperatingLeaseAndFinanceLeaseRightOfUseAsset	bcpc:OperatingLeaseAndFinanceLeaseRightOfUseAsset
Total right-of-use assets	$ 8,410	$ 7,338
Operating leases liabilities - current	$ 2,178	$ 2,475
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	bcpc:OperatingAndFinanceLeaseLiabilityCurrent	bcpc:OperatingAndFinanceLeaseLiabilityCurrent
Finance leases liabilities - current	$ 159	$ 0
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	bcpc:OperatingAndFinanceLeaseLiabilityCurrent	bcpc:OperatingAndFinanceLeaseLiabilityCurrent
Total lease liabilities, current	$ 2,337	$ 2,475
Lease liabilities - non-current	$ 3,607	$ 4,827
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	bcpc:OperatingAndFinanceLeaseLiabilityNoncurrent	bcpc:OperatingAndFinanceLeaseLiabilityNoncurrent
Finance leases liabilities - non-current	$ 2,472	$ 0
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	bcpc:OperatingAndFinanceLeaseLiabilityNoncurrent	bcpc:OperatingAndFinanceLeaseLiabilityNoncurrent
Total lease liabilities, non-current	$ 6,079	$ 4,827