Receivables

Our trade receivables are generally not collateralized. At December 31, 2015 and December 31, 2014, 26% and 39% of our gross trade receivables were from customers in the United States, respectively. Other than Venezuela, as further discussed below, no other country or single customer accounted for more than 10% of our gross trade receivables at these dates.

Venezuela. During the first quarter of 2015, we began utilizing the new SIMADI exchange rate mechanism to remeasure our net monetary assets denominated in Bolívares, at a market rate of 192 Bolívares per United States dollar as compared to the official exchange rate of 6.3 Bolívares per United States dollar we had previously utilized, resulting in a foreign currency devaluation loss of $199 million. See Note 3 and “Management’s Discussion and Analysis of Financial Condition and Results of Operations – Business Environment and Results of Operations” for further information.

Our total outstanding trade receivables in Venezuela were $704 million, which is more than 10% of our gross trade receivables, as of December 31, 2015, compared to $670 million, or approximately 9% of our gross trade receivables, as of December 31, 2014. We have experienced delays in collecting payment on our receivables from our primary customer in Venezuela, which contributed to the increase in those receivables during the period. This was partially offset by a decline due to the currency devaluation in the first quarter of 2015. These receivables are not disputed, and we have not historically had material write-offs relating to this customer. Additionally, we routinely monitor the financial stability of our customers. Of the $704 million of receivables in Venezuela as of December 31, 2015, the majority of which are United States dollar-denominated receivables, $175 million has been classified as long-term and included within “Other assets” on our consolidated balance sheets. Of the $670 million receivables in Venezuela as of December 31, 2014, $256 million has been classified as long-term and included within “Other assets” on our consolidated balance sheets.

The following table presents a rollforward of our allowance for bad debts for 2013, 2014, and 2015.



Millions of dollars	Balance at Beginning of Period		Charged to Costs and Expenses		Write-Offs			Balance at End of Period
Year ended December 31, 2013	$	92	$	39	$	(14	)	$	117
Year ended December 31, 2014	117		26		(6		)	137
Year ended December 31, 2015	137		44		(36		)	145