Goodwill and Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill [Table Text Block]

Goodwill The following table provides a reconciliation of changes in goodwill for the six months ended June 30, 2019:

	Driveline			Metal Forming		Powertrain			Casting		Consolidated
	(in millions)
Balance as of December 31, 2018	$	212.1		$	552.4	$	377.3		$	—	$	1,141.8
Reorganization	187.2			190.1		(377.3		)	—		—
Foreign currency translation	(1.1		)	0.2		—			—		(0.9		)
Balance as of June 30, 2019	$	398.2		$	742.7	$	—		$	—	$	1,140.9

Schedule of Finite-Lived Intangible Assets [Table Text Block]

The following table provides a reconciliation of the gross carrying amount and associated accumulated amortization for AAM's other intangible assets, which are all subject to amortization:

	June 30,							December 31,
	2019							2018
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
	(in millions)
Capitalized computer software	$	41.0	$	(24.5	)	$	16.5	$	38.0	$	(20.1	)	$	17.9
Customer platforms	952.2		(158.7		)	793.5		952.2		(123.5		)	828.7
Customer relationships	147.0		(21.3		)	125.7		147.0		(16.5		)	130.5
Technology and other	156.0		(28.6		)	127.4		156.2		(22.2		)	134.0
Total	$	1,296.2	$	(233.1	)	$	1,063.1	$	1,293.4	$	(182.3	)	$	1,111.1

Amortization expense for our intangible assets was $24.9 million and $49.9 million for the three and six months ended June 30, 2019, respectively, and $24.8 million and $49.7 million for the three and six months ended June 30, 2018, respectively. Estimated amortization expense for each of the full years 2019 through 2023 is approximately $100 million.