INCOME TAXES: - Tax assets and liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets:
Inventories	$ 47.0	$ 27.9
Capitalized exploration expenses	9.5	17.5
U.S. foreign tax credit carryforward, net of FIN 48 liability	280.2	284.2
U.S. tax effect of Peruvian deferred tax liability	174.1	162.6
Property, plant and equipment		1.2
Reserves	152.6	108.9
Mexican tax on consolidated dividends	14.5	13.6
Prepaids		11.1
Valuation allowance on US deferred tax assets, foreign tax credits and US tax effect on Peruvian deferred	(619.6)
Other	9.4	29.7
Total deferred tax assets	67.7	656.7
Liabilities:
Property, plant and equipment	(130.3)
Deferred charges	(16.9)	(35.4)
Unremitted foreign earnings		(45.7)
Other	(1.2)	(10.9)
Total deferred tax liabilities	(148.4)	(92.0)
Total net deferred tax (liabilities) / assets		$ 564.7
Total deferred tax (liabilities) / assets	$ (80.7)

Represents the amount as of the balance sheet date of the estimated future tax effects attributable to the difference between the methods used to account for capitalized exploration expenses for tax purposes and under generally accepted accounting principles.

No definition available.