Asset Retirement Obligations (Tables)

3 Months Ended

Mar. 31, 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		1,821		2,582
Revisions to estimated future reclamation cash flows		7,695		—
Payments		(248)		(337)
Balance as of March 31,		107,434		155,400
Less: current portion		(1,118)		(1,400)
Asset retirement obligation, net of current portion	$	106,316	$	154,000