INCOME TAXES - Movement of the valuation allowance (Details) - Allowance - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement of allowances
Beginning of the year	$ 65,399	$ 71,469	$ 55,959
Additions (Reversals)	11,051	(5,361)	14,486
Foreign exchange effect	72	(709)	1,024
Closing balance	$ 76,522	$ 65,399	$ 71,469

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs which have been charged to costs and expenses net of the total of recoveries of amounts due the Entity that had previously been written off as uncollectible using allowances (the valuation accounts that are netted against the cost of an asset to value it at its carrying value) and total of reestablishments of reserves (liabilities established to represent expected future costs) that had previously been utilized.

No definition available.

Name:	csiq_ValuationAllowancesAndReservesChargedToCostAndExpenseAndRecoveriesNet
Namespace Prefix:	csiq_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration