ASSET RETIREMENT OBLIGATIONS, CONTRACTUAL THIRD-PARTY RECLAMATION RECEIVABLES, AND RECLAMATION DEPOSITS (Tables)

12 Months Ended

Dec. 31, 2015

Asset Retirement Obligation Disclosure [Abstract]

Summary of asset retirement obligations, contractual third-party reclamation receivables and reclamation deposits

The asset retirement obligations (“ARO”), contractual third-party reclamation receivables, and reclamation deposits at December 31, 2015 are summarized below:

	Asset Retirement Obligations		Contractual Third-Party Reclamation Receivables		Reclamation Deposits
	(In thousands)
Coal - U.S.	$	251,116	$	89,408	$	77,364
Coal - Canada	110,978		5,527		—
Coal - WMLP	56,634		—		—
Power	1,035		—		—
Total	$	419,763	$	94,935	$	77,364

Changes in Company's asset retirement obligations

Changes in the Company’s asset retirement obligations were as follows:

	Years Ended December 31,
	2015			2014
	(In thousands)
Asset retirement obligations, beginning of year (including current portion)	$	452,745		$	279,864
Accretion	38,891			31,033
Liabilities settled	(30,363		)	(23,935		)
Changes due to amount and timing of reclamation	(24,533		)	10,042
Asset retirement obligations acquired	4,146			162,394
Changes due to foreign currency translation	(21,123		)	(6,653		)
Asset retirement obligations, end of year	419,763			452,745
Less current portion	(43,950		)	(43,289		)
Asset retirement obligations, less current portion	$	375,813		$	409,456

Carrying value and estimated fair value of reclamation deposits

The carrying value (which equals estimated fair value) of reclamation deposits at December 31, 2015 are as follows:

	(In thousands)
Cash and cash equivalents	$	45,819
Available-for-sale securities	31,545
	$	77,364

Available for Sale Reclamation Deposits

The cost basis, gross unrealized holding gains and fair value of available-for-sale securities are as follows:

	December 31,
	2015			2014
	(In thousands)
Cost basis	$	31,977		$	32,930
Gross unrealized holding gains	521			886
Gross unrealized holding losses	(953		)	(428		)
Fair value	$	31,545		$	33,388

Schedule of maturities of held-to-maturity investments

Maturities of available-for-sale securities were as follows at December 31, 2015: 

	Amortized  Cost		Fair  Value
	(In thousands)
Due within one year	$	1,127	$	1,057
Due in five years or less	15,522		14,896
Due after five years to ten years	5,142		4,939
Due in more than ten years	14,924		14,921
	$	36,715	$	35,813

Maturities of available-for-sale securities are as follows at December 31, 2015:

	Cost		Fair Value
	(In thousands)
Within one year	$	592	$	529
Due in five years or less	16,156		16,049
Due after five years to ten years	6,207		5,925
Due in more than ten years	9,022		9,042
	$	31,977	$	31,545