Marketable Securities and Restricted Funds

We routinely invest excess cash and various restricted balances in securities such as commercial paper, bankers acceptances, corporate debt securities, Canadian equity securities, treasury bills and money market securities in the U.S. and Canada. We do not purchase marketable securities for speculative purposes; therefore we do not have any securities classified as trading securities. While we do not routinely sell marketable securities prior to their scheduled maturity dates, some of our investments may be held and restricted for insurance purposes, capital expenditures and NEB regulatory requirements, so these investments are classified as available-for-sale (AFS) marketable securities as they may occasionally be sold prior to their scheduled maturity dates due to the unexpected timing of cash needs. Initial investments in securities are classified as purchases of the respective type of securities (AFS marketable securities or held-to-maturity (HTM) marketable securities). Maturities of securities are classified within proceeds from sales and maturities of securities in the Condensed Consolidated Statements of Cash Flows.

AFS Securities. AFS Securities are as follows:



	Estimated Fair Value
	September 30, 2016		December 31, 2015
	(in millions)
Corporate debt securities (a)	$	20	$	31
Canadian equity securities (b)	17		—
Total available-for-sale securities	$	37	$	31

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(a)	Amounts related to certain construction projects.


(b)	Amounts related to restricted funds held and collected from customers of Western Canada Transmission & Processing and Express-Platte for Canadian pipeline abandonment in accordance with the NEB’s regulatory requirements.

Our AFS securities are classified on the Condensed Consolidated Balance Sheets as follows:



	Estimated Fair Value
	September 30, 2016		December 31, 2015
	(in millions)
Restricted funds
Investments and other assets—other	$	31	$	11
Non-restricted funds
Current assets—other	6		20
Total available-for-sale securities	$	37	$	31

At September 30, 2016, the weighted-average contractual maturity of outstanding AFS securities was less than one year.

There were no material gross unrealized holding gains or losses associated with investments in AFS securities at September 30, 2016 or December 31, 2015.

HTM Securities. HTM securities are as follows:



		Estimated Fair Value
Description	Condensed Consolidated Balance Sheets Caption	September 30, 2016		December 31, 2015
		(in millions)
Bankers acceptances	Current assets—other	$	44	$	30
Canadian government securities	Current assets—other	25		24
Money market securities	Current assets—other	8		3
Canadian government securities	Investments and other assets—other	52		50
Bankers acceptances	Investments and other assets—other	—		12
Total held-to-maturity securities		$	129	$	119

All of our HTM securities are restricted funds pursuant to certain M&N Canada and Express-Platte (our crude oil pipeline system) debt agreements. The funds restricted for M&N Canada, plus future cash from operations that would otherwise be available for distribution to the partners of M&N Canada, are required to be placed in escrow until the balance in escrow is sufficient to fund all future debt service on the M&N Canada 6.90% senior secured notes. There are sufficient funds held in escrow to fund all future debt service on these M&N Canada notes as of September 30, 2016.

At September 30, 2016, the weighted-average contractual maturity of outstanding HTM securities was less than one year.

There were no material gross unrecognized holding gains or losses associated with investments in HTM securities at September 30, 2016 or December 31, 2015.

Other Restricted Funds. In addition to the portions of the AFS and HTM securities that were restricted as described above, we had other restricted funds totaling $25 million at September 30, 2016 and $11 million at December 31, 2015 classified as Current Assets—Other on the Condensed Consolidated Balance Sheets. Included in these restricted funds are $13 million at September 30, 2016 of funds received from the province of Ontario related to the Green Investment Fund that is to be distributed to eligible homeowners, based on specific energy conservation initiatives at Union Gas and $12 million and $11 million at September 30, 2016 and December 31, 2015, respectively, related to additional amounts for insurance.

We also had other restricted funds totaling $43 million at September 30, 2016 and $38 million at December 31, 2015 classified as Investments and Other Assets—Other on the Condensed Consolidated Balance Sheets. Included in these restricted funds are $17 million and $24 million at September 30, 2016 and December 31, 2015, respectively, related to funds held and collected from customers of Western Canada Transmission & Processing and Express-Platte for Canadian pipeline abandonment in accordance with the NEB’s regulatory requirements, $7 million and $14 million, respectively, related to certain construction projects and $19 million at September 30, 2016 of funds received from the province of Ontario related to the Green Investment Fund.

Changes in restricted balances are presented within Cash Flows from Investing Activities on our Condensed Consolidated Statements of Cash Flows.