Financial instruments and risk concentration (Tables)

12 Months Ended

Dec. 31, 2013

Risks and Uncertainties [Abstract]

Allowance for losses based on the expected collectability of accounts receivable

Details of these Accounts receivable allowances are as follows:

Accounts Receivable Allowances	Balance at Beginning of Year		Additions Charged (Credited) to Operating Results			Recoveries and Write-offs, Net		Balance at End of Year
2013	$	31	$	(9	)	$	—	$	22
2012	19		12			—		31
2011	18		1			—		19