The table below summarizes the balances outstanding under margin deposits, natural gas and power prepayments, and exposure under letters of credit and first priority liens for commodity procurement and risk management activities as of March 31, 2013 and December 31, 2012 (in millions):



	March 31, 2013		December 31, 2012
Margin deposits⁽¹⁾	$	257	$	196
Natural gas and power prepayments	35		35
Total margin deposits and natural gas and power prepayments with our counterparties⁽²⁾	$	292	$	231

Letters of credit issued	$	486	$	484
First priority liens under power and natural gas agreements	5		14
First priority liens under interest rate swap agreements	194		206
Total letters of credit and first priority liens with our counterparties	$	685	$	704

Margin deposits posted with us by our counterparties⁽¹⁾⁽³⁾	$	1	$	11
Letters of credit posted with us by our counterparties	2		1
Total margin deposits and letters of credit posted with us by our counterparties	$	3	$	12

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(1)

Balances are subject to master netting arrangements and presented on a gross basis on our Consolidated Condensed Balance Sheets. We do not offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation, and we do not offset amounts recognized for the right to reclaim, or the obligation to return, cash collateral with corresponding derivative instrument fair values. See Note 5 for further discussion of our derivative instruments subject to master netting arrangements.


(2)	At March 31, 2013 and December 31, 2012, $273 million and $211 million, respectively, were included in margin deposits and other prepaid expense and $19 million and $20 million, respectively, were included in other assets on our Consolidated Condensed Balance Sheets.


(3)	Included in other current liabilities on our Consolidated Condensed Balance Sheets.