Goodwill and Other Intangible Assets

The changes in the carrying amount of goodwill by segment for the three months ended March 30, 2019, are as follows:



(Amounts in millions)	Commercial & Industrial Group			Snap-on Tools Group		Repair Systems & Information Group			Total
Balance as of December 29, 2018	$	286.2		$	12.5	$	603.5		$	902.2
Currency translation	(2.1		)	—		(0.5		)	(2.6		)
Acquisitions and related adjustments	—			—		1.3			1.3
Balance as of March 30, 2019	$	284.1		$	12.5	$	604.3		$	900.9

Goodwill of $900.9 million as of March 30, 2019, includes $1.3 million from the acquisition of TMB. The goodwill from TMB is included in the Repair Systems and Information Group. See Note 3 for additional information on acquisitions.

Additional disclosures related to other intangible assets are as follows:



	March 30, 2019					December 29, 2018
(Amounts in millions)	Gross Carrying Value		Accumulated Amortization			Gross Carrying Value		Accumulated Amortization
Amortized other intangible assets:
Customer relationships	$	172.6	$	(110.5	)	$	172.2	$	(107.6	)
Developed technology	18.8		(18.6		)	18.5		(18.3		)
Internally developed software	158.0		(117.9		)	156.6		(116.6		)
Patents	35.9		(23.1		)	35.7		(22.9		)
Trademarks	3.2		(2.0		)	3.2		(2.0		)
Other	7.5		(3.0		)	7.3		(2.9		)
Total	396.0		(275.1		)	393.5		(270.3		)
Non-amortized trademarks	109.6		—			109.7		—
Total other intangible assets	$	505.6	$	(275.1	)	$	503.2	$	(270.3	)

Significant and unanticipated changes in circumstances, such as declines in profitability and cash flow due to significant and long-term deterioration in macroeconomic, industry and market conditions, the loss of key customers, changes in technology or markets, significant changes in key personnel or litigation, a significant and sustained decrease in share price and/or other events, including effects from the sale or disposal of a reporting unit, could require a provision for impairment of goodwill and/or other intangible assets in a future period. As of March 30, 2019, the company had no accumulated impairment losses.

The weighted-average amortization periods related to other intangible assets are as follows:



	In Years
Customer relationships	15
Developed technology	3
Internally developed software	6
Patents	8
Trademarks	6
Other	39

Snap-on is amortizing its customer relationships on both an accelerated and straight-line basis over a 15-year weighted-average life; the remaining intangibles are amortized on a straight-line basis. The weighted-average amortization period for all amortizable intangibles on a combined basis is 12 years.

The company’s customer relationships generally have contractual terms of three to five years and are typically renewed without significant cost to the company. The weighted-average 15-year life for customer relationships is based on the company’s historical renewal experience. Intangible asset renewal costs are expensed as incurred.

The aggregate amortization expense was $5.4 million and $6.6 million for the respective three months ended March 30, 2019, and March 31, 2018. Based on current levels of amortizable intangible assets and estimated weighted-average useful lives, estimated annual amortization expense is expected to be $20.7 million in 2019, $17.7 million in 2020, $15.4 million in 2021, $13.1 million in 2022, $12.0 million in 2023, and $10.0 million in 2024.