5. RESTRICTED INVESTMENTS, RECLAMATION DEPOSITS AND BOND COLLATERAL

Coal segments maintain government-required bond collateral that assures compliance with applicable federal and state regulations relating to the performance of final reclamation activities. The amounts deposited in the bond collateral account secure the bonds issued by the bonding company. The Corporate segment is required to obtain surety bonds in connection with its self-insured workers’ compensation plan and certain healthcare plans. The Company’s surety bond underwriters require collateral to issue these bonds.

The Company invests certain bond collateral, reclamation deposits and other restricted investments in a limited selection of fixed-income investment options and receives the corresponding investment returns. These investments are not available to meet the Company’s general cash needs. These investments include available-for-sale debt securities, which are reported at fair value with unrealized gains and losses excluded from earnings and reported in Accumulated other comprehensive loss in the Consolidated Balance Sheets (unaudited). On disposal, the resulting gain or loss is reported in Other expense in the Consolidated Statements of Operations (unaudited).

The Company’s carrying value and estimated fair value of Restricted investments, reclamation deposits and bond collateral as of June 30, 2018 were as follows:



	Restricted Investments and Bond Collateral		Reclamation Deposits		Total Restricted Investments, Reclamation Deposits and Bond Collateral
	(In thousands)
Cash and cash equivalents	$	47,900	$	9,782	$	57,682
Time deposits	2,475		—		2,475
Available-for-sale debt securities	75,644		70,011		145,655
	$	126,019	$	79,793	$	205,812

The Company’s carrying value and estimated fair value of Restricted investments, reclamation deposits and bond collateral as of December 31, 2017 were as follows:



	Restricted Investments and Bond Collateral		Reclamation Deposits		Total Restricted Investments, Reclamation Deposits and Bond Collateral
	(In thousands)
Cash and cash equivalents	$	42,549	$	6,643	$	49,192
Time deposits	2,467		—		2,467
Available-for-sale debt securities	78,157		70,378		148,535
	$	123,173	$	77,021	$	200,194

Available-for-Sale Debt Securities

The cost basis, gross unrealized holding gains and losses, and fair value of available-for-sale debt securities as of June 30, 2018 were as follows:



	Restricted Investments and Bond Collateral			Reclamation Deposits			Total Restricted Investments, Reclamation Deposits and Bond Collateral
	(In thousands)
Cost basis	$	76,281		$	70,255		$	146,536
Gross unrealized holding gains	465			696			1,161
Gross unrealized holding losses	(1,102		)	(940		)	(2,042		)
Fair value	$	75,644		$	70,011		$	145,655

The cost basis, gross unrealized holding gains and losses, and fair value of available-for-sale debt securities as of December 31, 2017 were as follows:



	Restricted Investments and Bond Collateral			Reclamation Deposits			Total Restricted Investments, Reclamation Deposits and Bond Collateral
	(In thousands)
Cost basis	$	78,564		$	70,576		$	149,140
Gross unrealized holding gains	521			617			1,138
Gross unrealized holding losses	(928		)	(815		)	(1,743		)
Fair value	$	78,157		$	70,378		$	148,535