We have investments in debt and equity securities held in Nuclear Decommissioning Trusts, Coal Mine Reclamation Escrow Account, and an Active Union Employee Medical Account. Investments in debt securities are classified as available-for-sale securities. We record both debt and equity security investments at their fair value on our Condensed Consolidated Balance Sheets. See Note 11 for a discussion of how fair value is determined and the classification of the investments within the fair value hierarchy. The investments in each trust or account are restricted for use and are intended to fund specified costs and activities as further described for each fund below.

Nuclear Decommissioning Trusts - To fund the future costs APS expects to incur to decommission Palo Verde, APS established external decommissioning trusts in accordance with NRC regulations. Third-party investment managers are authorized to buy and sell securities per stated investment guidelines. The trust funds are invested in fixed income securities and equity securities. Earnings and proceeds from sales and maturities of securities are reinvested in the trusts. Because of the ability of APS to recover decommissioning costs in rates, and in accordance with the regulatory treatment, APS has deferred realized and unrealized gains and losses (including credit losses) in other regulatory liabilities.

Coal Mine Reclamation Escrow Account - APS has investments restricted for the future coal mine reclamation funding related to Four Corners. This escrow account is primarily invested in fixed income securities. Earnings and proceeds from sales of securities are reinvested in the escrow account. Because of the ability of APS to recover coal mine reclamation costs in rates, and in accordance with the regulatory treatment, APS has deferred realized and unrealized gains and losses (including credit losses) in other regulatory liabilities. Activities relating to APS coal mine reclamation escrow account investments are included within the other special use funds in the table below.

Active Union Employee Medical Account - APS has investments restricted for paying active union employee medical costs. These investments may be used to pay active union employee medical costs incurred in the current and future periods. The account is invested primarily in fixed income securities. In accordance with the ratemaking treatment, APS has deferred the unrealized gains and losses (including credit losses) in other regulatory liabilities. Activities relating to active union employee medical account investments are included within the other special use funds in the table below.

The following tables present the unrealized gains and losses based on the original cost of the investment and summarizes the fair value of APS's Nuclear Decommissioning Trusts and other special use fund assets at March 31, 2020 and December 31, 2019 (dollars in thousands):



	March 31, 2020
	Fair Value							Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trusts		Other Special Use Funds		Total			Total Unrealized Gains		Total Unrealized Losses
Equity securities	$	427,915	$	6,752	$	434,667		$	234,695	$	(1,201	)
Available for sale-fixed income securities	490,421		244,640		735,061		(a)	41,455		(3,527		)
Other	2,090		1,331		3,421		(b)	—		—
Total	$	920,426	$	252,723	$	1,173,149		$	276,150	$	(4,728	)



	December 31, 2019
	Fair Value							Total Unrealized Gains		Total Unrealized Losses
Investment Type:	Nuclear Decommissioning Trusts		Other Special Use Funds		Total			Total Unrealized Gains		Total Unrealized Losses
Equity securities	$	529,716	$	7,142	$	536,858		$	337,681	$	—
Available for sale-fixed income securities	478,658		237,479		716,137		(a)	25,795		(669		)
Other	2,401		474		2,875		(b)	—		—
Total	$	1,010,775	$	245,095	$	1,255,870		$	363,476	$	(669	)

The following table sets forth APS's realized gains and losses relating to the sale and maturity of available-for-sale debt securities and equity securities, and the proceeds from the sale and maturity of these investment securities for the three months ended March 31, 2020 and 2019 (dollars in thousands):



	Three Months Ended March 31,
	Nuclear Decommissioning Trusts			Other Special Use Funds		Total
2020
Realized gains	$	3,313		$	—	$	3,313
Realized losses	(2,227		)	—		(2,227		)
Proceeds from the sale of securities (a)	178,196			16,891		195,087
2019
Realized gains	$	1,103		$	—	$	1,103
Realized losses	(1,405		)	—		(1,405		)
Proceeds from the sale of securities (a)	122,593			56,455		179,048

The fair value of APS's fixed income securities, summarized by contractual maturities, at March 31, 2020, is as follows (dollars in thousands):



	Nuclear Decommissioning Trust		Coal Mine Reclamation Escrow Account		Active Union Employee Medical Account		Total
Less than one year	$	11,911	$	37,498	$	40,872	$	90,281
1 year – 5 years	137,509		18,487		143,565		299,561
5 years – 10 years	112,834		—		—		112,834
Greater than 10 years	228,167		4,218		—		232,385
Total	$	490,421	$	60,203	$	184,437	$	735,061