Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 876,737	$ 708,906	$ 746,652
Cost of sales	600,961	486,774	518,189
Gross profit	275,776	222,132	228,463
Operating expenses:
Selling, general and administrative expenses	164,492	140,492	139,217
Research and development expenses	24,434	17,677	17,818
Impairment of intangible assets	0	6,568
Restructuring costs	4,143	9,849	7,214
Loss on partial settlement of pension plan	1,720
Total operating expenses	194,789	174,586	164,249
Income from operations	80,987	47,546	64,214
Other non-operating income and expense:
Interest expense, net	7,710	11,679	12,164
Loss on extinguishment of convertible debt	1,797	1,989
Other non-operating expense (income), net	353	(7)	963
Total other non-operating (income) expense, net	9,860	13,661	13,127
Income before income taxes	71,127	33,885	51,087
Provision for income taxes	19,700	8,745	15,744
Net income	51,427	25,140	35,343
Net loss attributable to non-controlling interest			63
Net income attributable to Altra Industrial Motion Corp.	$ 51,427	$ 25,140	$ 35,406
Weighted average shares, basic	28,949	25,719	26,064
Weighted average shares, diluted	29,064	25,872	26,109
Net income per share:
Basic net income attributable to Altra Industrial Motion Corp.	$ 1.78	$ 0.97	$ 1.36
Diluted net income attributable to Altra Industrial Motion Corp.	1.77	0.97	1.36
Cash dividend declared per share	$ 0.66	$ 0.60	$ 0.57