FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Summary of financial assets at fair value

The table below sets forth, by level, the Company’s financial assets and liabilities that are accounted for at fair value on a recurring basis:

	June 30, 2018
			Quoted Prices in Active Markets for Identical Assets or Liabilities		Significant Other Observable Inputs
	Fair Value		Level 1		Level 2
	(In thousands)
Assets:
Available-for-sale debt securities, included in Restricted investments, reclamation deposits and bond collateral	$	145,655	$	145,655	$	—
	$	145,655	$	145,655	$	—

	December 31, 2017
			Quoted Prices in Active Markets for Identical Assets or Liabilities		Significant Other Observable Inputs
	Fair Value		Level 1		Level 2
	(In thousands)
Assets:
Available-for-sale debt securities, included in Restricted investments, reclamation deposits and bond collateral	$	148,535	$	148,535	$	—
	$	148,535	$	148,535	$	—
Liabilities:
Warrants issued by WMLP, included in Other liabilities	$	296	$	—	$	296
	$	296	$	—	$	296

Estimated fair values of Company's debt

The estimated fair values of the Company’s debt with fixed and variable interest rates are as follows:

	Fixed Interest Rate				Variable Interest Rate
	Carrying Value		Fair Value		Carrying Value		Fair Value
	(In thousands)
June 30, 2018	$	375,950	$	108,523	$	710,999	$	232,139
December 31, 2017	375,789		195,189		672,618		351,856