FAIR VALUE MEASUREMENT (Tables)

9 Months Ended

Sep. 30, 2012

FAIR VALUE MEASUREMENT

Financial assets and liabilities measured at fair value within the fair value hierarchy

	Total		Level 1		Level 2		Level 3
Financial assets:
Cash equivalents and short-term investments(i)	$	11,473	$	—	$	11,473	$	—
Available-for-sale securities(ii)		92,150		92,150		—		—
Trade receivables(iii)		77,044		—		77,044		—
Fair value of derivative financial instruments(iv)		3,613		—		3,613		—
	$	184,280	$	92,150	$	92,130	$	—

• (i)

  Fair value approximates the carrying amounts of cash equivalents and short-term investments due to their short-term nature (classified within Level 2 of the fair value hierarchy).
  
  

  (ii)

  Available-for-sale securities are recorded at fair value using quoted market prices (classified within Level 1 of the fair value hierarchy).
  
  

  (iii)

  Trade receivables from provisional invoices for concentrate sales are valued using quoted forward rates derived from observable market data based on the month of expected settlement (classified within Level 2 of the fair value hierarchy).
  
  

  (iv)

  Derivative financial instruments are recorded at fair value using external broker-dealer quotations (classified within Level 2 of the fair value hierarchy).