4. Investments:

Investments in debt and equity securities

Investment securities we hold are classified as available-for-sale. Available-for-sale securities are carried at market value with unrealized gains and losses, net of any tax effect, added to or deducted from patronage capital, except that, in accordance with our rate-making treatment, realized and unrealized gains and losses from investment securities held in the nuclear decommissioning funds are directly added to or deducted from the regulatory asset or liability for asset retirement obligations. All realized and unrealized gains and losses are determined using the specific identification method. Approximately 65% of these gross unrealized losses were in effect for less than one year.


		(dollars in thousands)
		Gross Unrealized
2016		Cost		Gains		Losses			Fair Value

Equity	$	237,317	$	51,054	$	(5,041	)	$	283,330
Debt		201,492		1,167		(3,423	)		199,236
Other		3,339		–		(2	)		3,337

Total	$	442,148	$	52,221	$	(8,466	)	$	485,903



		(dollars in thousands)
		Gross Unrealized
2015		Cost		Gains		Losses			Fair Value

Equity	$	230,123	$	37,494	$	(9,635	)	$	257,982
Debt		189,700		1,158		(3,491	)		187,367
Other		5,255		–		(4	)		5,251

Total	$	425,078	$	38,652	$	(13,130	)	$	450,600

All of the available-for-sale investments are recorded at fair value in the accompanying consolidated balance sheets, therefore the carrying value equals the fair value.

The contractual maturities of debt securities available-for-sale, which are included in the estimated fair value table above, at December 31, 2016 and 2015 are as follows:


		(dollars in thousands)
		2016				2015
		Cost		Fair Value		Cost		Fair Value

Due within one year	$	8,292	$	8,268	$	8,559	$	8,612
Due after one year through five years		52,452		52,054		50,018		49,538
Due after five years through ten years		65,657		64,971		56,448		55,880
Due after ten years		75,091		73,943		74,675		73,337

Total	$	201,492	$	199,236	$	189,700	$	187,367

The following table summarizes the realized gains and losses and proceeds from sales of securities for the years ended December 31, 2016, 2015 and 2014:


		(dollars in thousands)
		2016			2015			2014

Gross realized gains	$	19,934		$	53,453		$	64,437
Gross realized losses		(20,030	)		(18,989	)		(46,258	)
Proceeds from sales		439,540			640,217			438,941

Investment in associated companies

Investments in associated companies were as follows at December 31, 2016 and 2015:


		(dollars in thousands)
		2016		2015

National Rural Utilities Cooperative Finance Corporation (CFC)	$	24,049	$	24,040
CT Parts, LLC		10,250		11,067
Georgia Transmission Corporation		27,285		25,872
Georgia System Operations Corporation		7,500		7,200
Other		3,699		3,831

Total	$	72,783	$	72,010

The CFC investments consist of capital term certificates required in connection with our membership in CFC and a voluntary investment in CFC member capital securities. Accordingly, there is no market for these investments. The investment in Georgia Transmission represents capital credits. The investment in Georgia System Operations represents loan advances. Repayments of these advances are due by December 2020.

CT Parts, LLC is an affiliated organization formed by us and Smarr EMC for the purpose of purchasing and maintaining spare parts inventory and for the administration of contracted services for combustion turbine generation facilities. Such investment is recorded at cost.

Rocky Mountain transactions

In December 1996 and January 1997, we entered into six long-term lease transactions relating to our 74.61% undivided interest in Rocky Mountain. In each transaction, we leased a portion of our undivided interest in Rocky Mountain to six separate owner trusts for the benefit of three investors, referred to as owner participants, for a term equal to 120% of the estimated useful life of Rocky Mountain. Immediately thereafter, the owner trusts leased their undivided interests in Rocky Mountain to our wholly owned subsidiary, Rocky Mountain Leasing Corporation, or RMLC, for a term of 30 years under six separate leases. RMLC then subleased the undivided interests back to us under six separate leases for an identical term.

In 2012, we terminated five of the six lease transactions prior to the end of their lease terms. The remaining lease in place represented approximately 10% of the original lease transactions. We have a guarantee for the basic rental payments under the remaining lease. The fair value amount relating to the guarantee of basic rent payments is immaterial to us principally due to the high credit rating of the payment undertaker. The basic rental payments remaining through the end of the lease are approximately $53,545,000.

The assets of RMLC are not available to pay our creditors.