Fair value measurement (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Carrying Amounts and Estimated Fair Values of Financial Instruments

The following table presents the carrying amounts and estimated fair values of the Group’s financial instruments at December 31, 2015 and 2014. Fair value is defined as the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

	December 31, 2015				December 31, 2014
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Financial assets:
Cash and cash equivalents	$	82,124	$	82,124	$	156,540	$	156,540
Restricted cash and bank deposits with maturity over three months		83,191		83,191		9,349		9,349
Accounts and notes receivable		90,786		90,786		33,755		33,755
Short-term investments		—		—		27,354		27,354
Other receivable		3,139		3,139		—		—
Finance lease receivable		30,322		30,322		—		—
Investment in an affiliate		13,950		15,149		—		—
Derivative asset		2,328		2,328		—		—
Total assets		305,480		307,309		226,998		226,998
Financial liabilities:
Borrowings		164,851		164,851		48,286		48,286
Accounts and notes payable		137,232		137,232		137,635		137,635
Other liabilities		73,436		73,436		60,905		60,905
Convertible bonds		54,062		54,315		32,575		39,423
Financing and capital lease obligations		8,796		8,796		10,092		10,092
Total liabilities	$	438,377	$	438,630	$	289,493	$	296,341