CONCENTRATION OF RISK

Accounts Receivable. The following table presents the components of accounts receivable, net of allowance for doubtful accounts:



	As of December 31,
	2015			2014
	(in thousands)

Crude oil, natural gas and NGLs sales	$	41,873		$	49,531
Joint interest billings	35,017			52,841
Derivative counterparties	24,437			12,582
Insurance reimbursement	879			11,212
Other	4,077			5,524
Allowance for doubtful accounts	(2,009		)	(486		)
Accounts receivable, net	$	104,274		$	131,204

Our accounts receivable primarily relate to sales of our crude oil, natural gas and NGLs production, other third parties that own working interests in the properties we operate and derivative counterparties. For the years ended December 31, 2015, 2014 and 2013, amounts written off to allowance for doubtful accounts were not material. As of December 31, 2015, we had one customer representing 10% or greater of our accounts receivable balance. Concord Energy represents 11.3% of our December 31, 2015 accounts receivable balance. As of December 31, 2014, we had two customers representing 10% or greater of our accounts receivable balance. Suncor Energy Marketing, Inc. and Concord Energy represented 11.1% and 10.3%, respectively.

Major Customers. The following table presents the individual customers constituting 10% or more of total revenues:



	Year Ended December 31,
Customer	2015		2014		2013

Concord Energy	23.2	%	18.3	%	—	%
Suncor Energy Marketing, Inc.	14.3	%	19.7	%	35.9	%
Shell Trading Company	13.8	%	—	%	—	%
DCP Midstream, LP	13.2	%	15.1	%	13.9	%
Teppco Crude Oil, LLC	—	%	12.9	%	8.0	%

The concentration of revenue represented by the customers noted above relate to our oil and gas exploration and production segment.

Derivative Counterparties. A significant portion of our liquidity is concentrated in derivative instruments that enable us to manage a portion of our exposure to price volatility from producing crude oil and natural gas. These arrangements expose us to credit risk of nonperformance by our counterparties. We primarily use financial institutions who are also major lenders under our revolving credit facility as counterparties to our derivative contracts. To date, we have had no derivative counterparty default losses. We have evaluated the credit risk of our derivative assets from our counterparties using relevant credit market default rates, giving consideration to amounts outstanding for each counterparty and the duration of each outstanding derivative position. Based on our evaluation, we have determined that the potential impact of nonperformance of our current counterparties on the fair value of our derivative instruments is not significant at December 31, 2015, taking into account the estimated likelihood of nonperformance.

The following table presents the counterparties that expose us to credit risk as of December 31, 2015, with regard to our derivative assets:



	Fair Value of Derivative Assets
Counterparty Name	As of December 31, 2015
	(in thousands)

Canadian Imperial Bank of Commerce (1)	$	78,102
JP Morgan Chase Bank, N.A (1)	71,012
Bank of Nova Scotia (1)	49,758
Wells Fargo Bank, N.A. (1)	32,474
NATIXIS (1)	29,754
Other lenders in our revolving credit facility	4,856
Other (2)	90
Total	$	266,046

____________

(1)Major lender in our revolving credit facility. See Note 8, Long-Term Debt.

(2)Represents one counterparty.

Note Receivable

The following table presents information regarding our note receivable outstanding as of December 31, 2015:



	Amount
	(in thousands)
Note receivable:
Principal outstanding, December 31, 2014	$	39,707
Paid-in-kind interest	3,362
Principal outstanding, December 31, 2015	$	43,069

In October 2014, we sold our entire 50% ownership interest in PDCM to an unrelated third-party. See Note 15, Assets Held for Sale, Divestitures and Discontinued Operations, for additional information regarding the sale. As part of the consideration, we received a promissory note (the “Note”) for a principal sum of $39.0 million, bearing varying interest rates beginning at 8% and increasing annually. Pursuant to the Note agreement, interest shall be paid quarterly, in arrears, commencing December 2014 and continuing on the last business day of each fiscal quarter thereafter. At the option of the issuer of the Note, an unrelated third-party, interest can be paid-in-kind (the “PIK Interest”) and any such PIK Interest will be added to the outstanding principal amount of the Note. As of December 31, 2015, the issuer of the Note had elected the PIK Interest option for each quarterly period since inception. The principal and any unpaid interest shall be due and payable in full in September 2020 and can be prepaid in whole or in part at any time, and in certain circumstances must be repaid prior to maturity. Any such prepayment will be made without premium or penalty. The Note is secured by a pledge of stock in certain subsidiaries of the unrelated third-party, debt securities and other assets.

Under the effective interest method, we recognized $4.5 million and $0.9 million of interest income for the years ended December 31, 2015 and 2014, respectively, of which $3.4 million and $0.7 million, respectively, was PIK Interest. As of December 31, 2015 and 2014, the $43.1 million and $39.7 million, respectively, outstanding balance on the Note was included in the consolidated balance sheet line item other assets.