(3) Goodwill, Customer Relationships and Other Intangible Assets

Goodwill, customer relationships and other intangible assets consisted of the following:



	June 30, 2018		December 31, 2017
	(Dollars in millions)
Goodwill	$	11,078	10,837
Customer relationships, less accumulated amortization of $477 and $126	$	7,990	8,845
Other intangible assets subject to amortization:
Trade names, less accumulated amortization of $17 and $4	113		126
Developed technology, less accumulated amortization of $37 and $9	283		252
Total other intangible assets, net	$	396	378

Our goodwill balance at December 31, 2017 includes $16 million of goodwill that was allocated to us from CenturyLink associated with differences in the deferred state income taxes that CenturyLink expects to realize due to its consolidation of our results of operations into its state tax returns.

Total amortization expense for intangible assets for the successor three and six months ended June 30, 2018 was $202 million and $396 million, respectively, and the predecessor three and six months ended June 30, 2017 was $52 million and $97 million, respectively. As of the successor date of June 30, 2018, the gross carrying amount of goodwill, customer relationships, indefinite-life and other intangible assets was $20 billion.

We estimate that total amortization expense for intangible assets for the successor years ending December 31, 2018 through 2022 will be as follows:



	(Dollars in millions)
2018 (remaining six months)	$	402
2019	805
2020	805
2021	805
2022	792

The following table shows the rollforward of goodwill from December 31, 2017 through June 30, 2018:



	(Dollars in millions)
As of December 31, 2017	$	10,837
Purchase accounting and other adjustments	306
Effect of foreign currency rate change	(65		)
As of June 30, 2018	$	11,078