Description of Business and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Reconciliation of Basic to Diluted Shares Outstanding

The following is a reconciliation of basic to diluted shares outstanding:

	Years Ended December 31,
	2017		2016		2015
Net income attributable to Altra Industrial Motion Corp.	$	51,427	$	25,140	$	35,406
Shares used in net income per common share – basic		28,949		25,719		26,064
Dilutive effect of the equity premium on Convertible Notes    at the average price of common stock		—		132		43
Incremental shares of unvested restricted common stock		115		21		2
Shares used in net income per common share – diluted		29,064		25,872		26,109

Depreciation of Property, Plant and Equipment, Including Capital Leases is Provided Using Straight-Line Method Over Estimated Useful Life of Asset

Depreciation of property, plant and equipment, including capital leases is provided using the straight-line method over the estimated useful life of the asset, as follows:

Buildings and improvements	15 to 45 years
Machinery and equipment	2 to 15 years
Capital lease	Life of lease

Changes in Accumulated Other Comprehensive Loss by Component

The following is a reconciliation of changes in Accumulated Other Comprehensive Loss for the periods presented:

	Gains and Losses on Cash Flow Hedges			Defined Benefit Pension Plans			Cumulative Foreign Currency Translation Adjustment			Total
Accumulated Other Comprehensive Loss by Component,    January 1, 2015	$	143		$	(4,818	)	$	(36,740	)	$	(41,415	)
Cumulative losses transferred from Lamiflex		—			—			(410	)		(410	)
Net current-period Other Comprehensive Income (Loss), net of tax		(283	)		(989	)		(20,735	)		(22,007	)
Accumulated Other Comprehensive Loss by Component,   December 31, 2015		(140	)		(5,807	)		(57,885	)		(63,832	)
Net current-period Other Comprehensive Income Loss, net of tax		(506	)		139			(11,887	)		(12,254	)
Accumulated Other Comprehensive Loss by Component,   December 31, 2016		(646	)		(5,668	)		(69,772	)		(76,086	)
Net current-period Other Comprehensive Income Loss, net of tax		194			924			24,038			25,156
Reclassification adjustment from loss on partial settlement of pension plan, net of tax		—			1,066			—			1,066
Accumulated Other Comprehensive Loss by Component,   December 31, 2017	$	(452	)	$	(3,678	)	$	(45,734	)	$	(49,864	)