Goodwill and Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill The following table provides a reconciliation of changes in goodwill for the six months ended June 30, 2017:



	Driveline		Metal Forming		Powertrain		Casting		Consolidated
	(in millions)
Balance as of December 31, 2016	$	130.1	$	23.9	$	—	$	—	$	154.0
Acquisition of MPG	—		509.3		467.9		399.1		1,376.3
Acquisition of USM Mexico	80.4		—		—		—		80.4
Foreign currency translation	0.1		—		—		—		0.1
Balance as of June 30, 2017	$	210.6	$	533.2	$	467.9	$	399.1	$	1,610.8

Schedule of Acquired Finite-Lived Intangible Assets by Major Class [Table Text Block]

Intangible Assets As a result of the acquisitions of MPG and USM Mexico, AAM identified and recognized certain intangible assets that are subject to amortization. The weighted-average amortization period for all intangible assets recognized as a result of these acquisitions is 13.6 years. The following table provides a breakout of the major intangible assets acquired by class:



	Estimated	June 30,
	Useful Lives	2017
	(years)	(in millions)
MPG
Customer platforms	14	$	970.0
Customer relationships	16-17	153.3
Technology and other	5-13	121.3
Total MPG		$	1,244.6

USM Mexico
Technology	13	$	29.5
Customer platforms	13	2.2
Total USM Mexico		$	31.7

Total		$	1,276.3

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 total intangible assets, which are all subject to amortization:



	June 30,							December 31,
	2017							2016
	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
	(in millions)
Capitalized computer software	$	34.0	$	(11.4	)	$	22.6	$	31.7	$	(8.5	)	$	23.2
e-AAM in-process research & development	5.7		—			5.7		5.3		—			5.3
Customer platforms	972.2		(17.9		)	954.3		—		—			—
Customer relationships	153.3		(2.3		)	151.0		—		—			—
Technology and other	150.8		(3.3		)	147.5		—		—			—
Total	$	1,316.0	$	(34.9	)	$	1,281.1	$	37.0	$	(8.5	)	$	28.5

Amortization expense for these intangible assets was $24.8 million and $26.4 million for the three and six months ended June 30, 2017, respectively, and $1.2 million and $2.3 million for the three and six months ended June 30, 2016, respectively. Estimated amortization expense for each of the next five years is as follows: approximately $76 million in 2017 and approximately $100 million in each of the years 2018 through 2021.