Goodwill and intangible assets

6 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

The changes in the carrying amount of goodwill for the six months ended December 31, 2019 are as follows:



	Diversified Industrial Segment		Aerospace Systems Segment		Total
Balance at June 30, 2019	$	5,355,165	$	98,640	$	5,453,805
Acquisitions	1,978,234		504,777		2,483,011
Foreign currency translation and other	18,354		—		18,354
Balance at December 31, 2019	$	7,351,753	$	603,417	$	7,955,170

The acquisitions line represents the goodwill allocation during the measurement period subsequent to the applicable acquisition date. Refer to Note 4 for further discussion.

Intangible assets are amortized on the straight-line method over their legal or estimated useful lives. The following summarizes the gross carrying value and accumulated amortization for each major category of intangible assets:



	December 31, 2019				June 30, 2019
	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Patents and technology	$	992,729	$	138,740	$	265,644	$	130,233
Trademarks	753,804		269,734		542,573		252,388
Customer lists and other	3,874,382		1,176,333		2,435,461		1,077,780
Total	$	5,620,915	$	1,584,807	$	3,243,678	$	1,460,401

Total intangible amortization expense for the six months ended December 31, 2019 was $128,174. The estimated amortization expense for the five years ending June 30, 2020 through 2024 is $277,637, $314,987, $308,949, $297,923 and $292,311, respectively.

Intangible assets are evaluated for impairment whenever events or circumstances indicate that the undiscounted net cash flows to be generated by their use over their expected useful lives and eventual disposition may be less than their net carrying value. No material intangible asset impairments occurred during the six months ended December 31, 2019.