Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2017

Asset Retirement Obligation Disclosure

Schedule of changes in carrying amount of asset retirement obligations

	2017		2016
Balance as of January 1,	$	98,166	$	153,155
Accretion expense		3,667		4,576
Revisions to estimated future reclamation cash flows		7,695		(54,787)
Payments		(520)		(712)
Balance as of June 30,		109,008		102,232
Less: current portion		(1,117)		(1,400)
Asset retirement obligation, net of current portion	$	107,891	$	100,832