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

9 Months Ended

Sep. 30, 2015

Schedule of Available-for-sale Securities [Line Items]

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

The asset retirement obligation ("ARO"), contractual third-party reclamation receivable, and reclamation deposits for each of the Company’s operating segments at September 30, 2015 are summarized below:

	Asset Retirement Obligation		Contractual Third-Party Reclamation Receivable		Reclamation Deposits
	(In thousands)
Coal - U.S.	$	279,864	$	109,758	$	77,425
Coal - Canada	116,061		5,638		—
Coal - WMLP	52,666		—		—
Power	1,016		—		—
Total	$	449,607	$	115,396	$	77,425

Changes in Company's asset retirement obligations

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

	Nine Months Ended September 30,
	2015			2014
	(In thousands)
Asset retirement obligations, beginning of year (including current portion)	$	452,745		$	279,864
Accretion	29,265			23,329
Liabilities settled	(23,421		)	(18,759		)
Changes due to amount and timing of reclamation	4,612			—
Asset retirement obligations acquired	3,769			102,075
Changes due to foreign currency translation	(17,363		)	(1,702		)
Asset retirement obligations, end of period	449,607			384,807
Less current portion	(47,462		)	(29,529		)
Asset retirement obligations, less current portion	$	402,145		$	355,278

Carrying value and estimated fair value of reclamation deposits

The Company’s carrying value and estimated fair value of its reclamation deposits at September 30, 2015 were as follows:

	Carrying Value		Fair Value		Fair Value Hierarchy
	(In thousands)
Cash and cash equivalents	$	46,544	$	46,544	Level 1
Available-for-sale securities	30,881		30,881		Level 1
	$	77,425	$	77,425

Available for sale reclamation deposits

The cost basis, gross unrealized holding gains and losses, and fair value of available-for-sale securities at September 30, 2015 were as follows (in thousands):

Cost basis	$	31,141
Gross unrealized holding gains	573
Gross unrealized holding losses	(833		)
Fair value	$	30,881

Reclamation Deposits

Schedule of Available-for-sale Securities [Line Items]

Investments Classified by Contractual Maturity Date

Maturities of available-for-sale securities were as follows at September 30, 2015:

	Cost Basis		Fair Value
	(In thousands)
Within one year	$	—	$	—
Due in five years or less	16,804		16,601
Due after five years to ten years	5,424		5,262
Due in more than ten years	8,913		9,018
	$	31,141	$	30,881