INVESTMENTS

Investments classified as available-for-sale, which consist primarily of debt securities, are stated at fair value. Unrealized gains and losses are excluded from earnings and reported as other comprehensive income, net of income tax effects. The cost of investments sold is determined in accordance with the specific identification method, and realized gains and losses are included in net investment income. We periodically assess our investments available-for-sale for other-than-temporary impairment. Any such other-than-temporary impairment loss is recognized as a realized loss, which is recorded through earnings, if related to credit losses.

During the three months ended March 31, 2014 and 2013, we recognized no losses from other-than-temporary impairments of our cash equivalents and available-for-sale investments.

We classified $4.3 million and $59.8 million as investments available-for-sale-noncurrent as of March 31, 2014 and December 31, 2013, respectively, because we did not intend to sell and we believed it may take longer than a year for such impaired securities to recover. This classification does not affect the marketability or the valuation of the investments, which are reflected at their market value as of March 31, 2014 and December 31, 2013.

As of March 31, 2014 and December 31, 2013, the amortized cost, gross unrealized holding gains and losses, and fair value of our current investments available-for-sale and our investments available-for-sale-noncurrent, after giving effect to other-than-temporary impairments, were as follows:



	March 31, 2014
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Carrying Value
	(Dollars in millions)
Current:
Asset-backed securities	$	415.8	$	3.5	$	(6.6	)	$	412.7
U.S. government and agencies	23.7		—		—			23.7
Obligations of states and other political subdivisions	758.7		7.1		(17.5		)	748.3
Corporate debt securities	501.7		3.7		(5.1		)	500.3
	$	1,699.9	$	14.3	$	(29.2	)	$	1,685.0
Noncurrent:
Asset-backed securities	$	0.8	$	—	$	(0.1	)	$	0.7
Corporate debt securities	4.1		—		(0.5		)	3.6
	$	4.9	$	—	$	(0.6	)	$	4.3



	December 31, 2013
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Carrying Value
	(Dollars in millions)
Current:
Asset-backed securities	$	394.7	$	3.4	$	(8.7	)	$	389.4
U.S. government and agencies	23.7		—		—			23.7
Obligations of states and other political subdivisions	734.3		5.9		(30.3		)	709.9
Corporate debt securities	449.8		3.6		(9.4		)	444.0
	$	1,602.5	$	12.9	$	(48.4	)	$	1,567.0
Noncurrent:
Asset-backed securities	$	1.3	$	—	$	(0.2	)	$	1.1
Obligations of states and other political subdivisions	53.4		—		(6.3		)	47.1
Corporate debt securities	13.2		—		(1.6		)	11.6
	$	67.9	$	—	$	(8.1	)	$	59.8

As of March 31, 2014, the contractual maturities of our current investments available-for-sale and our investments available-for-sale-noncurrent were as follows:



	Amortized Cost		Estimated Fair Value
Current:	(Dollars in millions)
Due in one year or less	$	56.0	$	56.3
Due after one year through five years	330.4		333.2
Due after five years through ten years	450.5		449.3
Due after ten years	447.2		433.5
Asset-backed securities	415.8		412.7
Total current investments available-for-sale	$	1,699.9	$	1,685.0

	Amortized Cost		Estimated Fair Value
Noncurrent:	(Dollars in millions)
Due after five years through ten years	2.1		1.9
Due after ten years	2.0		1.7
Asset-backed securities	0.8		0.7
Total noncurrent investments available-for-sale	$	4.9	$	4.3

Proceeds from sales of investments available-for-sale during the three months ended March 31, 2014 were $66.5 million. Gross realized gains and losses totaled $1.2 million and $0.9 million, respectively, for the three months ended March 31, 2014. Proceeds from sales of investments available-for-sale during the three months ended March 31, 2013 were $354.8 million. Gross realized gains and losses totaled $17.5 million and $0.2 million, respectively, for the three months ended March 31, 2013.

The following tables show our investments’ fair values and gross unrealized losses for individual securities that have been in a continuous loss position through March 31, 2014 and December 31, 2013. These investments are interest-yielding debt securities of varying maturities. We have determined that the unrealized loss position for these securities is primarily due to market volatility. Generally, in a rising interest rate environment, the estimated fair value of fixed income securities would be expected to decrease; conversely, in a decreasing interest rate environment, the estimated fair value of fixed income securities would be expected to increase. These securities may also be negatively impacted by illiquidity in the market.

The following table shows our current investments' fair values and gross unrealized losses for individual securities that have been in a continuous loss position through March 31, 2014:



	Less than 12 Months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(Dollars in millions)
Asset-backed securities	$	190.8	$	(5.5	)	$	40.1	$	(1.1	)	$	230.9	$	(6.6	)
Obligations of states and other political subdivisions	369.4		(9.6		)	146.4		(7.9		)	515.8		(17.5		)
Corporate debt securities	226.0		(4.6		)	15.8		(0.5		)	241.8		(5.1		)
	$	786.2	$	(19.7	)	$	202.3	$	(9.5	)	$	988.5	$	(29.2	)

The following table shows our noncurrent investments' fair values and gross unrealized losses for individual securities that have been in a continuous loss position through March 31, 2014:



	Less than 12 Months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(Dollars in millions)
Asset-backed securities	$	—	$	—		$	0.7	$	(0.1	)	$	0.7	$	(0.1	)
Corporate debt securities	1.9		(0.2		)	1.7		(0.3		)	3.6		(0.5		)
	$	1.9	$	(0.2	)	$	2.4	$	(0.4	)	$	4.3	$	(0.6	)

The following table shows the number of our individual securities-current that have been in a continuous loss position through March 31, 2014:



	Less than 12 Months	12 Months or More	Total
Asset-backed securities	81	22	103
Obligations of states and other political subdivisions	151	70	221
Corporate debt securities	193	15	208
	425	107	532

The following table shows the number of our individual securities-noncurrent that have been in a continuous loss position through March 31, 2014:



	Less than 12 Months	12 Months or More	Total
Asset-backed securities	—	1	1
Corporate debt securities	1	1	2
	1	2	3

The following table shows our current investments’ fair values and gross unrealized losses for individual securities that have been in a continuous loss position through December 31, 2013:



	Less than 12 Months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(Dollars in millions)
Asset-backed securities	$	225.3	$	(7.9	)	$	22.5	$	(0.8	)	$	247.8	$	(8.7	)
U.S. government and agencies	4.0		—			—		—			4.0		—
Obligations of states and other political subdivisions	453.5		(23.5		)	79.7		(6.8		)	533.2		(30.3		)
Corporate debt securities	242.8		(9.0		)	6.7		(0.4		)	249.5		(9.4		)
	$	925.6	$	(40.4	)	$	108.9	$	(8.0	)	$	1,034.5	$	(48.4	)

The following table shows the number of our individual securities-noncurrent that have been in a continuous loss position through December 31, 2013:



	Less than 12 Months					12 Months or More					Total
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	(Dollars in millions)
Asset-backed securities	$	0.5	$	(0.1	)	$	0.7	$	(0.1	)	$	1.2	$	(0.2	)
Obligations of states and other political subdivisions	17.4		(2.2		)	29.6		(4.1		)	47.0		(6.3		)
Corporate debt securities	7.5		(0.9		)	4.1		(0.7		)	11.6		(1.6		)
	$	25.4	$	(3.2	)	$	34.4	$	(4.9	)	$	59.8	$	(8.1	)