6. INTANGIBLE ASSETS AND GOODWILL

Changes in identifiable intangible assets and goodwill consisted of the following:


	December 30,		Disposition		Impairment		Amortization		December 29,
(in thousands)	2018		Adjustment		Charges		Expense		2019
Intangible assets subject to amortization	$	838,336	$	—	$	—	$	—	$	838,336
Accumulated amortization		(807,725)		—		—		(24,153)		(831,878)
		30,611		—		—		(24,153)		6,458
Mastheads		112,736		—		(49,941)		—		62,795
Goodwill		705,174		—		(284,996)		—		420,178
Total	$	848,521	$	—	$	(334,937)	$	(24,153)	$	489,431


	December 31,		Disposition		Impairment		Amortization		December 30,
(in thousands)	2017		Adjustment		Charges		Expense		2018
Intangible assets subject to amortization	$	839,284	$	(948)	$	—	$	—	$	838,336
Accumulated amortization		(761,013)		948		—		(47,660)		(807,725)
		78,271		—		—		(47,660)		30,611
Mastheads		149,951		—		(37,215)		—		112,736
Goodwill		705,174		—		—		—		705,174
Total	$	933,396	$	—	$	(37,215)	$	(47,660)	$	848,521

Impairment of Goodwill and Intangible Assets

During the year ended December 29, 2019, we performed an interim and annual testing of impairment of goodwill and intangible newspaper mastheads due to the continuing challenging business conditions and changes in our assessment of profitability in future years. The fair values of our reporting units for goodwill impairment testing and individual newspaper mastheads were estimated using the present value of expected future cash flows, using estimates, judgments and assumptions (see Note 3) that we believe were appropriate in the circumstances. As a result, we recorded goodwill impairment charges of $258.1 million and $285.0 million during the third quarter and the full year ended December 29, 2019, respectively. We also recorded an intangible newspaper masthead impairment charges of $37.2 million and $49.9 million in third quarter and full year ended December 29, 2019, respectively. These impairments were recorded in the goodwill and other asset write-downs line item on our consolidated statements of operations.

During the third quarter and full year ended December 30, 2018, based on our interim and annual impairment testing of intangible newspaper mastheads, we recorded $14.1 million and $37.2 million, respectively, in masthead impairments. These impairment charges were recorded in other asset write-downs line item on our consolidated statements of operations. There were no goodwill impairment charges during 2018.

Accumulated changes in indefinite lived intangible assets and goodwill as of December 29, 2019, and December 30, 2018, consisted of the following:


	December 29, 2019						December 30, 2018
	Original Gross		Accumulated		Carrying		Original Gross		Accumulated		Carrying
(in thousands)	Amount		Impairment		Amount		Amount		Impairment		Amount
Mastheads	$	684,500	$	(621,705)	$	62,795	$	684,500	$	(571,764)	$	112,736
Goodwill		3,571,111		(3,150,933)		420,178		3,571,111		(2,865,937)		705,174
Total	$	4,255,611	$	(3,772,638)	$	482,973	$	4,255,611	$	(3,437,701)	$	817,910

Amortization expense was $24.2 million and $47.7 million in 2019 and 2018, respectively. A majority of the intangible assets subject to amortization became fully amortized in the second quarter of 2019 and therefore amortization expense during the last six months of 2019 was significantly lower. The estimated amortization expense for the five succeeding fiscal years is as follows:


	Amortization
	Expense
Year	(in thousands)
2020	$	803
2021		680
2022		655
2023		667
2024		640