We had goodwill of $2,079.3 million and $2,090.2 million as of March 31, 2020 and December 31, 2019, respectively. The change in the net carrying amount of goodwill by segment was as follows:

(In millions)	Cabinets			Plumbing			Doors & Security			Total Goodwill
Goodwill at December 31, 2019^(a)	$	925.5		$	747.3		$	417.4		$	2,090.2
Year-to-date translation adjustments		(2.5	)		(7.4	)		(1.0	)		(10.9	)
Goodwill at March 31, 2020^(a)	$	923.0		$	739.9		$	416.4		$	2,079.3

We also had net identifiable intangible assets of $1,139.9 million and $1,168.9 million as of March 31, 2020 and December 31, 2019, respectively. The $22.1 million decrease in gross identifiable intangible assets was due to foreign translation adjustments and tradename impairment charges of $9.5 million in our Cabinets segment.

The gross carrying value and accumulated amortization by class of identifiable intangible assets as of March 31, 2020 and December 31, 2019 were as follows:

(In millions)	As of March 31, 2020							As of December 31, 2019
	Gross Carrying Amounts		Accumulated Amortization			Net Book Value		Gross Carrying Amounts		Accumulated Amortization			Net Book Value
Indefinite-lived tradenames	$	620.8	$	—		$	620.8	$	635.6	$	—		$	635.6
Amortizable intangible assets
Tradenames		19.8		(12.6	)		7.2		20.6		(12.9	)		7.7
Customer and contractual relationships		796.0		(304.6	)		491.4		803.9		(299.6	)		504.3
Patents/proprietary technology		74.8		(54.3	)		20.5		73.4		(52.1	)		21.3
Total		890.6		(371.5	)		519.1		897.9		(364.6	)		533.3
Total identifiable intangibles	$	1,511.4	$	(371.5	)	$	1,139.9	$	1,533.5	$	(364.6	)	$	1,168.9

Amortizable identifiable intangible assets, principally customer relationships, are subject to amortization over their estimated useful life, ranging from 2 to 30 years, based on the assessment of a number of factors that may impact useful life, which includes customer attrition rates and other relevant factors.

In March 2020, the World Health Organization declared a global pandemic related to COVID-19, and governments around the globe enacted significant and wide-ranging measures to slow and limit the transmission of the virus, including stay at home orders in the United States and globally. The impacts of these measures is expected to negatively impact our net sales in the second quarter and later periods of 2020. We considered the forecasted impact of COVID-19 combined with the results of our 2019 annual impairment tests to be a triggering event requiring a March 31, 2020 impairment test for three of our indefinite-lived tradenames in our Cabinets segment.

In the first quarter of 2020, we recognized an impairment charge of $9.5 million related to one of these indefinite-lived tradenames. This charge was primarily the result of lower expected sales of custom cabinetry products related to the impact of COVID-19. In the fourth quarter of 2019, we recognized an impairment charge of $12.0 million related to the same indefinite-lived tradename, which was the result of a strategic shift associated with new segment leadership and acceleration of our capacity rebalancing initiatives from custom cabinetry products to value-based cabinetry products as a result of lower than expected sales of custom cabinetry products compared to prior forecasts. As of March 31, 2020, the estimated fair value of this tradename equaled its carrying value of $29.1 million.

In the third quarter of 2019, we recognized an impairment charge of $29.5 million related to a second indefinite-lived tradename in our Cabinets segment, which was primarily the result of a continuing shift in consumer demand from semi-custom cabinetry products to value-priced cabinetry products, which led to consecutive downward adjustments of internal sales forecasts and future growth rates associated with the tradename. As of March 31, 2020, the estimated fair value of this tradename exceeded its carrying value of $85.0 million by less than 10%.

As of March 31, 2020, the estimated fair value of the third tradename exceeded its carrying value of $36.2 million by less than 10%.

The fair values of these tradenames were measured using the relief-from-royalty approach, which estimates the present value of royalty income that could be hypothetically earned by licensing the tradename to a third party over its remaining useful life. Some of the more significant assumptions inherent in estimating the fair values include forecasted revenue growth rates for the tradename, assumed royalty rate, and a market-participant discount rate that reflects the level of risk associated with the tradenames’ future revenues and profitability. We selected the assumptions used in the financial forecasts using historical data, supplemented by current and anticipated market conditions, estimated growth rates, and management plans. These assumptions represent Level 3 inputs of the fair value hierarchy (refer to Note 8).

A reduction in the estimated fair value of these three tradenames could trigger additional impairment charges in future periods. Events or circumstances that could have a potential negative effect on the estimated fair value of our reporting units and indefinite-lived tradenames include: lower than forecasted revenues, more severe impacts of COVID-19 than expected, actual new construction and repair and remodel growth rates that fall below our assumptions, actions of key customers, increases in discount rates, continued economic uncertainty, higher levels of unemployment, weak consumer confidence, lower levels of discretionary consumer spending, a decrease in royalty rates and a decline in the trading price of our common stock. We cannot predict the occurrence of certain events or changes in circumstances that might adversely affect the carrying value of goodwill and indefinite-lived assets.