Our liabilities consist mainly of fixed and variable rate debt, denominated in U.S. dollars and various other currencies, which we issue in the global capital markets, while our assets consist primarily of U.S. dollar denominated, fixed rate receivables. We enter into interest rate swaps, interest rate floors, and foreign currency swaps to economically hedge the interest rate and foreign currency risks that result from the different characteristics of our assets and liabilities. Our use of derivative transactions is intended to reduce long-term fluctuations in the fair value of assets and liabilities caused by market movements. All of our derivative activities are authorized and monitored by our management and our Asset Liability Committee which provides a framework for financial controls and governance to manage market risk.

The accounting guidance permits the net presentation on our Consolidated Balance Sheets of derivative receivables and derivative payables with the same counterparty and the related cash collateral when a legally enforceable master netting agreement exists. When we meet this condition, we elect to present such balances on a net basis.

Our International Swaps and Derivatives Association (“ISDA”) Master Agreements are our master netting agreements which permit multiple transactions to be cancelled and settled with a single net balance paid to either party. The master netting agreements also contain reciprocal collateral agreements which require the transfer of cash collateral to the party in a net asset position across all transactions. Our collateral agreements with substantially all our counterparties include a zero threshold, full collateralization arrangement. Although we have daily valuation and collateral exchange arrangements with all of our counterparties, due to the time required to move collateral, there may be a delay of up to one day between the exchange of collateral and the valuation of our derivatives. We would not be required to post additional collateral to the counterparties with whom we were in a net liability position at September 30, 2019 if our credit ratings were to decline, since we fully collateralize without regard to credit ratings with these counterparties. In addition, as our collateral agreements include legal right of offset provisions, collateral amounts are netted against derivative assets or derivative liabilities, the net amount of which is included in Other assets or Other liabilities in our Consolidated Balance Sheets.

The following tables show the financial statement line item and amount of our derivative assets and liabilities that are reported in our Consolidated Balance Sheets:

	September 30, 2019					March 31, 2019
			Fair					Fair
	Notional		value			Notional		value
Other assets:
Interest rate swaps	$	37,394	$	689		$	49,254	$	472
Foreign currency swaps		54		21			2,771		72
Total	$	37,448	$	710		$	52,025	$	544

Counterparty netting				(456	)				(441	)
Collateral held				(204	)				(42	)
Carrying value of derivative contracts – Other assets			$	50				$	61

Other liabilities:
Interest rate swaps	$	63,632	$	928		$	57,593	$	622
Foreign currency swaps		12,696		1,081			9,796		785
Total	$	76,328	$	2,009		$	67,389	$	1,407

Counterparty netting				(456	)				(441	)
Collateral posted				(1,515	)				(940	)
Carrying value of derivative contracts – Other liabilities			$	38				$	26

As of September 30, 2019, we held excess collateral of $1 million, which we did not use to offset derivative assets and was recorded in Other liabilities in our Consolidated Balance Sheets, and we posted excess collateral of $2 million, which we did not use to offset derivative liabilities and was recorded in Other assets in our Consolidated Balance Sheets. As of March 31, 2019, we held excess collateral of $2 million, which we did not use to offset derivative assets and was recorded in Other liabilities in our Consolidated Balance Sheets and we posted excess collateral of $17 million, which we did not use to offset derivative liabilities and was recorded in Other assets in our Consolidated Balance Sheets.

The following table summarizes the components of interest expense, including the location and amount of gains and losses on derivative instruments and related hedged items, as reported in our Consolidated Statements of Income:

	Three Months Ended						Six Months Ended
	September 30,						September 30,
	2019			2018			2019			2018
Interest expense on debt	$	639		$	637		$	1,294		$	1,238
Interest expense (income) on derivatives		37			(22	)		49			(47	)
Interest expense on debt and derivatives		676			615			1,343			1,191

Gains on debt denominated in foreign currencies		(475	)		(161	)		(460	)		(807	)
Losses on foreign currency swaps		474			172			366			855
(Gains) losses on U.S. dollar interest rate swaps		(62	)		76			61			145
Total interest expense	$	613		$	702		$	1,310		$	1,384

Interest expense on debt and derivatives represents net interest settlements and changes in accruals. Gains and losses on derivatives and debt denominated in foreign currencies exclude net interest settlements and changes in accruals. Cash flows associated with derivatives are reported in Net cash provided by operating activities in our Consolidated Statements of Cash Flows.