The components of net investment income from continuing operations were as follows:

YEARS ENDED DECEMBER 31	2018			2017			2016
(in millions)
Fixed maturities	$	217.7		$	205.8		$	202.1
Limited partnerships		24.1			15.3			8.0
Equity securities		17.0			18.0			18.6
Mortgage loans		14.0			11.4			9.1
Other investments		4.8			3.4			3.4
Gross investment income		277.6			253.9			241.2
Less investment expenses		(10.2	)		(10.0	)		(9.6	)
Net investment income	$	267.4		$	243.9		$	231.6

Effective January 1, 2018, with the implementation of ASC No. 2016-01, the change in fair value of limited partnerships previously reported using the cost method are reported in net investment income, of which $5.3 million relates to holding gains on securities still owned at December 31, 2018.

The carrying values of fixed maturity securities on non-accrual status at December 31, 2018 and 2017 were not material. The effects of non-accruals for the years ended December 31, 2018, 2017 and 2016, compared with amounts of net investment income that would have been recognized in accordance with the original terms of the fixed maturities were also not material.

Net realized and unrealized gains (losses) on investments from continuing operations, including OTTI, were as follows:

YEARS ENDED DECEMBER 31	2018			2017			2016
(in millions)
Equity securities	$	(43.4	)	$	19.8		$	25.4
Fixed maturities		(5.8	)		3.6			(15.5	)
Other investments		(1.5	)		(2.3	)		0.3
Net realized and unrealized investment gains (losses)	$	(50.7	)	$	21.1		$	10.2

Effective January 1, 2018, as a result of the implementation of ASC No. 2016-01, net realized and unrealized investment losses include changes in the fair value of equity securities. Previously, equity securities were categorized as available-for-sale and unrealized gains and losses were reported in AOCI, a separate component of shareholders’ equity.

The following table provides pre-tax net realized and unrealized losses on equity securities from continuing operations:

For the years ended December 31, 2017 and 2016, there were net unrealized gains on equity securities of $56.8 million and $37.8 million, respectively, recognized in AOCI.

Included in the net realized and unrealized investment gains (losses) were OTTI of investment securities totaling $4.6 million, $5.6 million and $27.4 million in 2018, 2017 and 2016, respectively.

For 2018, total OTTI from continuing operations was $5.4 million. Of this amount, $4.6 million was recognized in earnings and the remaining $0.8 million was recorded as unrealized losses in AOCI. The $4.6 million of OTTI recognized in earnings relates to $2.6 million of fixed maturity securities and $2.0 million of other invested assets.

For 2017, total OTTI from continuing operations was $5.9 million. Of this amount, $5.6 million was recognized in earnings and the remaining $0.3 million was recorded as unrealized losses in AOCI. The $5.6 million of OTTI recognized in earnings relates to $2.0 million of other invested assets, $1.8 million of fixed maturity securities and $1.8 million of equities.

For 2016, total OTTI from continuing operations was $20.6 million. Of this amount, $27.4 million was recognized in earnings including $6.8 million which was transferred from unrealized losses in AOCI. The $27.4 million of OTTI recognized in earnings was related primarily to $16.0 million of fixed maturity securities that the Company intended to sell, $8.4 million of credit impairments and $2.7 million of equities.

The methodology and significant inputs used to measure the amount of credit losses on fixed maturities in 2018, 2017 and 2016 were as follows:

Corporate bonds - the Company utilized a financial model that derives expected cash flows based on probability-of-default factors by credit rating and asset duration and loss-given-default factors based on security type. These factors are based on historical data provided by an independent third-party rating agency. In addition, other market data relevant to the realizability of contractual cash flows may be considered.

The following table provides rollforwards of the cumulative amounts related to the Company’s credit loss portion of the OTTI losses on fixed maturity securities from continuing operations for which the non-credit portion of the loss is included in other comprehensive income.

YEARS ENDED DECEMBER 31	2018			2017			2016
(in millions)
Credit losses as of the beginning of the year	$	3.6		$	9.6		$	17.7
Credit losses on securities for which an OTTI was not previously recognized		1.0			0.4			6.1
Additional credit losses on securities for which an OTTI was previously recognized		0.1			0.1			2.3
Reductions for securities sold, matured or called		(0.9	)		(6.1	)		(4.3	)
Reductions for securities reclassified as intend to sell		—			(0.4	)		(12.2	)
Credit losses as of the end of the year	$	3.8		$	3.6		$	9.6

The proceeds from sales of available-for-sale securities and the gross realized gains and gross realized losses on those sales, were as follows:

YEARS ENDED DECEMBER 31
(in millions)
	Proceeds		Gross		Gross
2018	from Sales		Gains		Losses
Fixed maturities, excluding held-for-sale (Chaucer)	$	296.5	$	2.1	$	8.4
Fixed maturities, held-for-sale		276.8		1.7		1.7
Total fixed maturities	$	573.3	$	3.8	$	10.1

2017
Fixed maturities, excluding held-for-sale (Chaucer)	$	306.8	$	8.1	$	7.8
Fixed maturities, held-for-sale		188.0		4.1		0.4
Total fixed maturities	$	494.8	$	12.2	$	8.2

2016
Fixed maturities, excluding held-for-sale (Chaucer)	$	348.2	$	10.0	$	5.1
Fixed maturities, held-for-sale		215.6		1.7		1.9
Total fixed maturities	$	563.8	$	11.7	$	7.0

Beginning in 2018, equity securities are no longer classified as available-for-sale. Proceeds from the sale of equity securities for the years ended December 31, 2017 and 2016 were $128.8 million and $245.0 million, respectively, resulting primarily in gross realized gains of $18.8 million and $31.1 million, respectively.