LONG-TERM DEBT AND OTHER FINANCING ARRANGEMENTS Other credit facilities and capital lease obligations composition (Details) $ in Thousands, Kč in Millions		3 Months Ended
		Mar. 31, 2019 CZK (Kč)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Capital Leased Assets [Line Items]
Credit facilities	[1],[2],[3]		$ 0	$ 0
Finance leases (Note 11)			15,613	15,891
Total credit facilities and finance leases			15,613	15,891
Less: current maturities			(5,802)	(5,545)
Total non-current credit facilities and finance leases			9,811	10,346
BMG Bank Mendes Gans [Member]
Capital Leased Assets [Line Items]
Credit facilities			0
Line Of Credit Facility Cash Pooling Arrangement Deposit			56,500	$ 36,800
Ceska Sporitelna [Member]
Capital Leased Assets [Line Items]
Receivables Subject to a Factoring Agreement, Recourse or Non-Recourse Basis		Kč 475.0	20,700
Factoring Fee, Percentage		0.19%
Debt Instrument, Basis Spread on Variable Rate		0.95%
KB [Member]
Capital Leased Assets [Line Items]
Receivables Subject to a Factoring Agreement, Recourse or Non-Recourse Basis		Kč 270.0	$ 11,800
Factoring Fee, Percentage		0.11%
Debt Instrument, Basis Spread on Variable Rate		0.95%
Global Funds IFN S.A. [Member]
Capital Leased Assets [Line Items]
Factoring Fee, Percentage		4.00%
Debt Instrument, Basis Spread on Variable Rate		6.00%

[1] (1) We have a cash pooling arrangement with Bank Mendes Gans (“BMG”), a subsidiary of ING Bank N.V. (“ING”), which enables us to receive credit throughout the group in respect of cash balances which our subsidiaries deposit with BMG. Cash deposited by our subsidiaries with BMG is pledged as security against the drawings of other subsidiaries up to the amount deposited.As at March 31, 2019, we had deposits of US$ 56.5 million in and no drawings on the BMG cash pool. Interest is earned on deposits at the relevant money market rate. As at December 31, 2018, we had deposits of US$ 36.8 million in and no drawings on the BMG cash pool.

[2] (2) Under a factoring framework agreement with Factoring Česka spořitelna a.s., up to CZK 475.0 million (approximately US$ 20.7 million) of receivables from certain customers in the Czech Republic may be factored on a recourse or non-recourse basis. The facility has a factoring fee of 0.19% of any factored receivable and bears interest at one-month PRIBOR plus 0.95% per annum for the period that receivables are factored and outstanding.

[3] (4) Under a factoring framework agreement with Global Funds IFN S.A., receivables from certain customers in Romania may be factored on a non-recourse basis. The facility has a factoring fee of 4.0% of any factored receivable and bears interest at 6.0% per annum from the date the receivables are factored to the due date of the factored receivable.