Investments

Investments in Marketable Securities

Investments in available-for-sale securities were liquidated prior to December 31, 2015. Proceeds from sales and maturities of available-for-sale debt securities amounted to $90.3 million and $13.5 million for the years ended December 31, 2015 and 2014, respectively. The Company realized zero net gains associated with those sales and maturities during the years ended December 31, 2015 and 2014.

Equity Method Investments

The Company’s equity method investments include its joint venture interest in Middlemount in addition to certain other equity method investments. The table below summarizes the book value of those investments, which is reported in “Investments and other assets” in the consolidated balance sheets, and the related (income) loss from equity affiliates:



	Book Value at December 31,				(Income) Loss from Equity Affiliates for the Year Ended December 31,
	2016		2015		2016			2015		2014
	(Dollars in millions)
Equity interest in Middlemount Coal Pty Ltd	$	—	$	—	$	(22.6	)	$	7.0	$	98.5
Other equity method investments	0.5		1.5		6.4			8.9		9.1
Total equity method investments	$	0.5	$	1.5	$	(16.2	)	$	15.9	$	107.6

During the years ended December 31, 2016, 2015 and 2014, Middlemount generated revenues of approximately $183 million, $160 million and $165 million (on a 50% basis). During the year ended December 31, 2015, due to sustained weakness in seaborne metallurgical coal prices that had persisted longer than the Company had previously anticipated, a history of operating losses at the mine and the magnitude of the difference between the estimated fair value and the carrying value of its equity investment, the Company determined the carrying value of its equity investment in Middlemount to be other-than-temporarily impaired. Correspondingly, the Company recorded an impairment charge of $46.6 million to write down the carrying value of its equity investment. The Company determined its Subordinated Loans to Middlemount were also fully impaired resulting in an additional impairment charge of $229.9 million. A total impairment charge related to Middlemount of $276.5 million was reflected in "Asset impairment" in the consolidated statement of operations for the year ended December 31, 2015. Refer to Note 4. "Asset Impairment" for additional background surrounding the impairment charge recognized in 2015. At December 31, 2016, the Company had priority loans related to Middlemount with a carrying value of $84.8 million reflected in "Investments and other assets". Refer to Note 10. "Financing Receivables" for additional background on the Company's loans with Middlemount as of December 31, 2016.

In 2014, the Company recorded to "(Gain) loss from equity affiliates" its pro-rata share of a valuation allowance of $52.3 million on Middlemount's Australian net deferred tax assets. Based on a Middlemount's history of operating losses driven by sustained weakness in seaborne metallurgical coal prices, and considering available sources of taxable income, it was determined in 2014 that the net deferred tax assets are no longer considered more likely than not of being realized.

There is no remaining unamortized basis difference as of December 31, 2016 between the amount at which the Company's equity investment in Middlemount is carried and the amount of underlying equity in net assets of Middlemount. Middlemount had current assets, noncurrent assets, current liabilities and noncurrent liabilities of $47.3 million, $263.4 million, $363.5 million and $50.3 million, respectively, as of December 31, 2016 and $31.7 million, $348.0 million, $362.2 million and $10.5 million, respectively, as of December 31, 2015 (on a 50% basis).

In addition to its equity method investment, the Company periodically makes loans to Middlemount pursuant to the related stockholders' agreement. Refer to Note 10. "Financing Receivables" for additional details surrounding those loans.