Altra Industrial Motion (AIMC) 10-Q27 Oct 142014 Q3 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2014	Oct. 23, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Entity Registrant Name	'ALTRA INDUSTRIAL MOTION CORP.	'
Entity Central Index Key	'0001374535	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	26,635,336

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current assets:	'	'
Cash and cash equivalents	$42,994	$63,604
Trade receivables, less allowance for doubtful accounts of $2,802 and $2,245 at September 30, 2014 and December 31, 2013, respectively	117,872	109,084
Inventories	135,383	143,665
Deferred income taxes	9,821	9,754
Assets Held-for-sale, Current	573	0
Income tax receivable	1,918	5,032
Prepaid expenses and other current assets	8,195	18,066
Total current assets	316,756	349,205
Property, plant and equipment, net	152,776	157,535
Intangible assets, net	115,530	118,768
Goodwill	104,653	104,339
Deferred income taxes	894	934
Other non-current assets, net	4,188	4,895
Total assets	694,797	735,676
Current liabilities:	'	'
Accounts payable	43,914	51,180
Accrued payroll	24,194	23,983
Accruals and other current liabilities	38,649	34,979
Deferred income taxes	44	44
Income tax payable	4,088	12,963
Current portion of long-term debt	14,532	16,924
Total current liabilities	125,421	140,073
Long-term debt - less current portion and net of unaccreted discount	237,062	261,348
Deferred income taxes	53,822	53,813
Pension liabilities	7,565	8,025
Long-term taxes payable	762	1,038
Other long-term liabilities	844	1,055
Redeemable non-controlling interest	979	991
Commitment and Contingencies (See Note 17)	'	'
Stockholdersâ€™ equity:	'	'
Common stock ($0.001 par value, 90,000,000 shares authorized, 26,515,072 and 26,819,795 issued and outstanding at September 30, 2014 and December 31, 2013, respectively)	27	27
Additional paid-in capital	142,841	154,471
Retained earnings	155,198	133,231
Accumulated other comprehensive loss	-29,724	-18,396
Total stockholdersâ€™ equity	268,342	269,333
Total liabilities, redeemable non-controlling interest and stockholdersâ€™ equity	$694,797	$735,676

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]	'	'
Allowance for doubtful accounts	$2,761	$2,245
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	26,761,559	26,819,795
Common stock, shares outstanding	26,761,559	26,819,795

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Income Statement [Abstract]	'	'	'	'
Net sales	$202,520	$175,443	$627,856	$541,688
Cost of sales	140,187	121,785	437,257	378,112
Gross profit	62,333	53,658	190,599	163,576
Operating expenses:	'	'	'	'
Selling, general and administrative expenses	39,067	31,672	117,828	96,742
Research and development expenses	3,818	3,002	11,719	9,150
Restructuring costs	1,643	97	1,643	655
Total operating expenses	44,528	34,771	131,190	106,547
Income from operations	17,805	18,887	59,409	57,029
Other non-operating income and expense:	'	'	'	'
Interest expense, net	3,000	2,567	8,991	7,830
Other non-operating expense (income), net	-313	686	446	783
Total other non-operating income expense, net	2,687	3,253	9,437	8,613
Income before income taxes	15,118	15,634	49,972	48,416
Provision for income taxes	8,170	5,176	18,843	15,423
Net income	6,948	10,458	31,129	32,993
Net (income) loss attributable to non-controlling interest	-2	43	-21	77
Net income attributable to Altra Industrial Motion Corp.	$6,946	$10,501	$31,108	$33,070
Weighted average shares, basic (in shares)	26,648	26,780	26,785	26,750
Weighted average shares, diluted (in shares)	27,334	26,836	27,557	26,852
Net income per share:	'	'	'	'
Basic net income attributable to Altra Industrial Motion Corp. (in usd per share)	$0.26	$0.39	$1.16	$1.24
Diluted net income attributable to Altra Industrial Motion Corp. (in usd per share)	$0.25	$0.39	$1.13	$1.23
Cash dividend declared (in usd per share)	$0.12	$0.10	$0.34	$0.28

Condensed_Consolidated_Stateme1

Condensed Consolidated Statement of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net Income	$6,948	$10,458	$31,129	$32,993
Other Comprehensive income (loss):	'	'	'	'
Foreign currency translation adjustment	-12,341	-6,727	-11,437	-46
Change in fair value of interest rate swap, net of tax	229	-346	109	191
Other comprehensive income (loss)	-12,112	-7,073	-11,328	145
Comprehensive (loss) income	-5,164	3,385	19,801	33,138
Comprehensive (income) loss attributable to noncontrolling interest	105	43	12	77
Comprehensive income (loss) attributable to Altra Industrial Motion Corp.	($5,059)	$3,428	$19,813	$33,215

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013
Cash flows from operating activities	'	'
Net Income	$31,129	$32,993
Adjustments to reconcile net income to net cash flows:	'	'
Depreciation	17,238	16,047
Amortization of intangible assets	6,884	4,882
Amortization of deferred financing costs	699	646
Loss on foreign currency, net	461	593
Amortization of inventory fair value adjustment	2,264	0
Accretion of debt discount, net	2,527	2,331
Loss on disposal of fixed assets	195	0
Provision for deferred taxes	1,350	0
Stock based compensation	2,633	2,397
Changes in assets and liabilities:	'	'
Trade receivables	-11,452	-8,756
Inventories	5,276	3,451
Accounts payable and accrued liabilities	-6,682	9,197
Other current assets and liabilities	9,704	254
Other operating assets and liabilities	-188	-1,866
Net cash from operating activities	62,038	62,169
Cash flows from investing activities	'	'
Purchase of property, plant and equipment	-16,464	-14,361
Proceeds from Sale of Land Held-for-use	274	0
Payments to Acquire Businesses, Net of Cash Acquired	-15,092	0
Net cash from investing activities	-31,282	-14,361
Cash flows from financing activities	'	'
Payments on term loan facility	-21,478	-3,750
Payments on revolving credit facility	-9,190	-54,304
Dividend payments	-8,644	-4,852
Proceeds from equipment loan	2,245	3,550
Payment of equipment and working capital notes	-1,028	-1,100
Borrowing under revolving credit facility	5,000	0
Shares surrendered for tax withholding	-1,447	-1,166
Payments on mortgages and other	-435	-540
Purchases of common stock under share repurchase program	-12,816	0
Net cash from financing activities	-47,793	-62,162
Effect of exchange rate changes on cash and cash equivalents	-3,573	-528
Net change in cash and cash equivalents	-20,610	-14,882
Cash and cash equivalents at beginning of year	63,604	85,154
Cash and cash equivalents at end of period	42,994	70,272
Cash paid during the period for:	'	'
Interest	6,504	5,561
Income taxes	$23,333	$15,156

Consolidated_Statement_of_Stoc

Consolidated Statement of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Additional Paid in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) [Member]	Redeemable Non-Controlling Interest [Member]
In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) [Member]	Redeemable Non-Controlling Interest [Member]
Beginning balance at Dec. 31, 2012	$232,012	$27	$152,188	$103,200	($23,403)	$1,239
Beginning balance, shares at Dec. 31, 2012	'	26,724,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Stock-based compensation and vesting of restricted stock	1,231	'	1,231	'	'	'
Stock-based compensation and vesting of restricted stock, Shares	'	94,000	'	'	'	'
Net income attributable to Altra Industrial Motion Corp.	33,070	'	'	33,070	'	'
Net loss attributable to non-controlling interest	77	'	'	'	'	-77
Dividends declared	-7,471	'	'	-7,471	'	'
Change in fair value of interest rate swap	191	'	'	'	191	'
Cumulative foreign currency translation adjustment	-46	'	'	'	-46	'
Ending balance at Sep. 28, 2013	258,910	27	153,419	128,722	-23,258	1,041
Ending balance, shares at Sep. 28, 2013	'	26,818,000	'	'	'	'
Beginning balance at Dec. 31, 2013	269,333	27	154,471	133,231	-18,396	991
Beginning balance, shares at Dec. 31, 2013	'	26,820,000	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Stock-based compensation and vesting of restricted stock	1,186	'	1,186	'	'	'
Stock-based compensation and vesting of restricted stock, Shares	'	78,000	'	'	'	'
Net income attributable to Altra Industrial Motion Corp.	31,108	'	'	31,108	'	'
Net loss attributable to non-controlling interest	-21	'	'	'	'	21
Dividends declared	-9,141	'	'	-9,141	'	'
Change in fair value of interest rate swap	109	'	'	'	109	'
Cumulative foreign currency translation adjustment	-11,437	'	'	'	-11,437	-33
Repurchase of common stock	-12,816	'	-12,816	'	'	'
Repurchase of common stock, shares	'	-383,000	'	'	'	'
Ending balance at Sep. 30, 2014	$268,342	$27	$142,841	$155,198	($29,724)	$979
Ending balance, shares at Sep. 30, 2014	'	26,515,000	'	'	'	'

Organization_and_Nature_of_Ope

Organization and Nature of Operations	9 Months Ended
Organization and Nature of Operations	Sep. 30, 2014
Accounting Policies [Abstract]	'
Organization and Nature of Operations	'
	Organization and Nature of Operations
	Headquartered in Braintree, Massachusetts, Altra Industrial Motion Corp. (the “Company” or "Altra"), through its wholly-owned subsidiary Altra Power Transmissions, Inc. (“APT”), is a leading multi-national designer, producer and marketer of a wide range of electro-mechanical power transmission products. The Company brings together strong brands covering over 42 product lines with production facilities in eleven countries. Altra’s leading brands include Ameridrives Couplings, Bauer Gear Motor, Bibby Turboflex, Boston Gear, Delroyd Worm Gear, Formsprag Clutch, Guardian Couplings, Huco, Industrial Clutch, Inertia Dynamics, Kilian Manufacturing, Lamiflex Couplings, Marland Clutch, Matrix, Nuttall Gear, Stieber Clutch, Svendborg Brakes, TB Wood’s, Twiflex, Warner Electric, Warner Linear, and Wichita Clutch.
	In November 2013, Altra Holdings, Inc. changed its name to Altra Industrial Motion Corp., and Altra Industrial Motion, Inc., the Company’s wholly owned subsidiary, changed its name to Altra Power Transmission, Inc.

Basis_of_Presentation

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 30, 2014
Accounting Policies [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	The Company was formed on November 30, 2004 following acquisitions of The Kilian Company (“Kilian”) and certain subsidiaries of Colfax Corporation (“Colfax”). During 2006, the Company acquired Hay Hall Holdings Limited (“Hay Hall”) and Bear Linear. On April 5, 2007, the Company acquired TB Wood’s Corporation (“TB Wood’s”), and on October 5, 2007, the Company acquired substantially all of the assets of All Power Transmission Manufacturing, Inc. On May 29, 2011, the Company acquired substantially all of the assets of Danfoss Bauer GmbH relating to its gear motor business (“Bauer”). On July 11, 2012, the Company acquired 85% of privately held Lamiflex do Brasil Equipamentos Industriais Ltda. (“Lamiflex”). On December 17, 2013, the Company completed the acquisition of Svendborg Brakes A/S, now known as Svendborg Brakes ApS, and S.B. Patent Holding ApS (together “Svendborg”). The Company acquired all the issued and outstanding shares of Svendborg from Friction Holding A/S. On July 1, 2014, the Company acquired all of the issued and outstanding shares of Guardian Ind., Inc. (“Guardian Couplings”).
	The Company’s unaudited condensed consolidated financial statements have been prepared in accordance with the instructions to Form 10-Q and do not include all of the information and note disclosures required by accounting principles generally accepted in the United States of America. These statements should be read in conjunction with the financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments, consisting only of normal recurring adjustments, necessary to present fairly the Company’s financial position as of September 30, 2014 and December 31, 2013, results of operations for the quarters and year to date periods ended September 30, 2014 and September 28, 2013, and cash flows for the year to date periods ended September 30, 2014 and September 28, 2013.
	The Company modified its quarterly reporting calendar effective at the beginning of fiscal year 2014 to report on a calendar month-end basis with all quarters ending on the last day of the final month of each quarter. Historically, the Company’s reporting calendar for all quarters presented has consisted of thirteen weeks of operations per quarter. The Company’s fiscal year end will remain December 31. The effects of the change in the reporting periods did not have a significant impact on the consolidated financial statements.

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	9 Months Ended
Fair Value of Financial Instruments	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value of Financial Instruments	'
	Fair Value of Financial Instruments
	The carrying values of financial instruments, including accounts receivable, cash equivalents, accounts payable, and other accrued liabilities approximate fair value. Debt under the Company’s Credit Agreement including a Term Loan Facility and a Revolving Credit Facility approximate the fair values due to the variable rate nature at current market rates.
	The carrying amount of the 2.75% Convertible Notes (the “Convertible Notes”) was $85 million at each of September 30, 2014 and December 31, 2013. The estimated fair value of the Convertible Notes at September 30, 2014 and December 31, 2013 was $102.8 million and $116.5 million, respectively, based on inputs other than quoted prices that are observable for the Convertible Notes (level 2).
	Included in cash and cash equivalents as of September 30, 2014 and December 31, 2013 are money market fund investments of $0.3 million and $16.6 million, respectively, which are reported at fair value based on quoted market prices for such investments (level 1).

Changes_in_Accumulated_Other_C

Changes in Accumulated Other Comprehensive Income (Loss) by Component	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Changes in Accumulated Other Comprehensive Income (Loss) by Component	'
	Changes in Accumulated Other Comprehensive Income (Loss) by Component
	The following is a reconciliation of changes in Accumulated Other Comprehensive Income (Loss) by Component for the periods presented:



		Gains and		Defined			Cumulative			Total
		Losses on		Benefit			Foreign
		Cash Flow		Pension			Currency
		Hedges		Plans			Translation
							Adjustment
	Accumulated Other Comprehensive Income (Loss) by Component, January 1, 2013	$	—	$	(4,607	)	$	(18,796	)	$	(23,403	)

	Net current-period Other Comprehensive Income (Loss)	191		—			(46		)	145

	Accumulated Other Comprehensive Income (Loss) by Component, Balance at September 28, 2013	$	191	$	(4,607	)	$	(18,842	)	$	(23,258	)




		Gains and		Defined			Cumulative			Total
		Losses on		Benefit			Foreign
		Cash Flow		Pension			Currency
		Hedges		Plans			Translation
							Adjustment
	Accumulated Other Comprehensive Income (Loss) by Component, January 1, 2014	$	135	$	(3,133	)	$	(15,398	)	$	(18,396	)

	Net current-period Other Comprehensive Income (Loss)	109		—			(11,437		)	(11,328		)

	Accumulated Other Comprehensive Income (Loss) by Component, Balance at September 30, 2014	$	244	$	(3,133	)	$	(26,835	)	$	(29,724	)

Net_Income_per_Share

Net Income per Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Net Income per Share	'
	Net Income per Share
	Basic earnings per share is based on the weighted average number of shares of common stock outstanding, and diluted earnings per share is based on the weighted average number of shares of common stock outstanding and all potentially dilutive common stock equivalents outstanding. Common stock equivalents are included in the per share calculations when the effect of their inclusion is dilutive.

	The following is a reconciliation of basic to diluted net income per share:


		Quarter Ended				Year to Date Ended
		30-Sep-14		28-Sep-13		30-Sep-14		28-Sep-13
	Net income attributable to Altra Industrial Motion Corp.	$	6,946	$	10,501	$	31,108	$	33,070

	Shares used in net income per common share - basic	26,648		26,780		26,785		26,750

	Dilutive effect of the equity premium on Convertible Notes at the average price of common stock	626		—		687		—

	Incremental shares of unvested restricted common stock	60		56		85		102

	Shares used in net income per common share - diluted	27,334		26,836		27,557		26,852

	Earnings per share:
	Basic net income attributable to Altra Industrial Motion Corp.	$	0.26	$	0.39	$	1.16	$	1.24

	Diluted net income attributable to Altra Industrial Motion Corp.	$	0.25	$	0.39	$	1.13	$	1.23

	During the quarter and year to date periods ended September 30, 2014, the average price of the Company’s common stock exceeded the current conversion price of the Company’s Convertible Notes resulting in additional shares being included in the shares used in net income per common share in the diluted earnings per share calculation above (See Note 12).

Inventories

Inventories	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	Inventories
	Inventories are generally stated at the lower of cost or market, using the first-in, first-out (“FIFO”) method. Market is defined as net realizable value. Inventories located at certain subsidiaries are stated at the lower of cost or market, principally using the last-in, first-out (“LIFO”) method. Inventories at September 30, 2014 and December 31, 2013 consisted of the following:


		30-Sep-14		31-Dec-13
	Raw materials	$	40,545	$	56,824

	Work in process	16,352		18,432

	Finished goods	78,486		68,409

		$	135,383	$	143,665

	Approximately 6.7% and 7.5% of total inventories were valued using the LIFO method as of September 30, 2014 and December 31, 2013, respectively. The Company recorded a $0.3 million adjustment as a component of cost of sales to value the inventory on a LIFO basis for the year to date period ended September 30, 2014. There was no provision recorded as a component of cost of sales to value the inventory on a LIFO basis for the quarter and year to date periods ended September 28, 2013.

Warranty_Costs

Warranty Costs	9 Months Ended
	Sep. 30, 2014
Guarantees [Abstract]	'
Warranty Costs	'
	Warranty Costs
	The contractual warranty period generally ranges from 3 months to 2 years with certain warranties extending for longer periods based on the product and application of the product and are recorded in accruals and other current liabilities on the Company's balance sheet. Changes in the carrying amount of accrued product warranty costs for each of the year to date periods ended September 30, 2014 and September 28, 2013 are as follows:


		30-Sep-14			28-Sep-13
	Balance at beginning of period	$	8,739		$	5,625

	Accrued current period warranty expense	1,314			1,758

	Payments	(1,900		)	(1,743		)
	Balance at end of period	$	8,153		$	5,640

Income_Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The estimated effective income tax rates recorded for the year to date periods ended September 30, 2014 and September 28, 2013, were based upon management’s best estimate of the effective tax rate for the entire year.
	The Company and its subsidiaries file a consolidated federal income tax return in the United States as well as consolidated and separate income tax returns in various state and foreign jurisdictions. In the normal course of business, the Company is subject to examination by taxing authorities in all of these jurisdictions. With the exception of certain foreign jurisdictions, the Company is no longer subject to income tax examinations for the tax years prior to 2010.
	Additionally, the Company has indemnification agreements with the sellers of the Guardian, Svendborg, Bauer and Lamiflex entities that generally provide for reimbursement to the Company for payments made in satisfaction of tax liabilities relating to pre-acquisition periods.
	The Company recognizes interest and penalties related to unrecognized tax benefits as a component of income tax expense in the condensed consolidated statements of operations. At September 30, 2014 and December 31, 2013, the Company had $0.2 million and $0.4 million of accrued interest and penalties, respectively.

Pension_and_Other_Employee_Ben

Pension and Other Employee Benefits	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Pension and Other Employee Benefits	'
	Pension and Other Employee Benefits
	Defined Benefit (Pension)
	The Company sponsors various defined benefit (pension) plans for certain, primarily unionized, active employees (those in the employment of the Company at, and certain employees hired since, November 30, 2004).
	The following tables represent the reconciliation of the net periodic benefit cost of the defined benefit (pension) plans as of September 30, 2014 and September 28, 2013:



		Quarter Ended
		Pension Benefits
		30-Sep-14			28-Sep-13
	Service cost	$	38		$	37

	Interest cost	273			246

	Expected return on plan assets	(269		)	(267		)
	Amortization of net gain	27			41

	Net periodic benefit cost (income)	$	69		$	57




		Year to Date Ended
		Pension Benefits
		30-Sep-14			28-Sep-13
	Service cost	$	114		$	113

	Interest cost	819			738

	Expected return on plan assets	(807		)	(801		)
	Amortization of net gain	81			125

	Net periodic benefit cost (income)	$	207		$	175


	The Company made $0.2 million in contributions during the year to date period ended September 30, 2014. The Company does not have any future required contributions during the remainder of the year ended December 31, 2014.
	Partial Pension Settlement
	During October 2014, the Company initiated a plan to offer lump-sum settlements to vested terminated participants of its domestic pension plan. Participants were notified of the settlement offers during October 2014. The acceptance of these offers will trigger partial settlement accounting with a maximum charge to earnings of approximately $0.8 million. The funds to provide for these settlements will be paid from plan assets.

Derivative_Financial_Instrumen

Derivative Financial Instruments

9 Months Ended

Sep. 30, 2014

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

Interest Rate Swap

In April 2013, the Company entered into an interest rate swap agreement designed to fix the variable interest rate payable on a portion of its outstanding borrowings, currently $85.0 million, under the Credit Agreement, at 0.626% exclusive of the margin under the Former Credit Agreement. The interest rate swap agreement and its terms are also applicable to the variable interest rate borrowings under the current Credit Agreement.

The interest rate swap agreement was designed to manage exposure to interest rates on the Company’s variable rate indebtedness. The Company recognizes all derivatives on its balance sheet at fair value. The Company has designated its interest rate swap agreement, which is forward-dated, as a cash flow hedge. Changes in the fair value of the swap are recognized in other comprehensive income until the hedged items are recognized in earnings. Hedge ineffectiveness, if any, associated with the swap will be reported by the Company in interest expense. There was no ineffectiveness associated with the swap during the quarter ended September 30, 2014, nor was any amount excluded from ineffectiveness testing for the period.

The estimated fair value of the Company’s interest rate swap agreement with certain financial institutions (“Interest Rate Swap”) was based on inputs other than quoted prices that are observable for the Interest Rate Swap (level 2). Inputs include present value of fixed and projected floating rate cash flows over the term of the swap contract.

The fair value of the swap recognized in other non-current assets, net and in other comprehensive income (loss) is as follows:

Fair Value

Notional

30-Sep-14

31-Dec-13

Effective Date

Amount

Fixed Rate

Maturity

April 30, 2013

85,000

0.626

30-Nov-16

243

213

Concentrations_of_Credit_Segme

Concentrations of Credit, Segment Data and Workforce	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Concentrations of Credit, Segment Data and Workforce	'
	Concentrations of Credit, Segment Data and Workforce
	Financial instruments, which are potentially subject to counter party performance and concentrations of credit risk, consist primarily of trade accounts receivable. The Company manages these risks by conducting credit evaluations of customers prior to delivery or commencement of services. When the Company enters into a sales contract, collateral is normally not required from the customer. Payments are typically due within 30 days of billing. An allowance for potential credit losses is maintained, and losses have historically been within management’s expectations. No customer represented greater than 10% of total sales for each of the year to date periods ended September 30, 2014 and September 28, 2013.
	The Company is also subject to counter party performance risk of loss in the event of non-performance by counterparties to financial instruments, such as cash and investments. Cash and cash equivalents are held by well-established financial institutions and invested in AAA rated mutual funds. The Company is exposed to swap counterparty credit risk with financial institutions. The Company’s counterparty is a well-established financial institution.

	The Company has three operating segments that are regularly reviewed by our chief operating decision maker. Each of these operating segments represents a unit that produces mechanical power transmission products. The Company aggregates all of the operating segments into one reportable segment. The three operating segments are expected to have similar long-term average gross profit margins. All of our products are sold by one global sales force and we have one global marketing function with the exception of the newly acquired Svendborg business for which the Company is in the process of integrating sales and marketing activities. Strategic markets and industries are determined for the entire company and then targeted by the brands. All of our operating segments have common manufacturing and production processes. Each operating segment includes a machine shop which uses similar equipment and manufacturing techniques. Each of our operating segments uses common raw materials, such as aluminum, steel and copper. The materials are purchased and procurement contracts are negotiated by one global purchasing function.
	The Company serves the general industrial market by selling to original equipment manufacturers (“OEM”) and distributors. Our OEM and distributor customers serve the general industrial market. Resource allocation decisions such as capital expenditure requirements and headcount requirements are made at a consolidated level and allocated to the individual operating segments.
	Discrete financial information is not available by product line at the level necessary for management to assess performance or make resource allocation decisions.
	Net sales to third parties by geographic region are as follows:


		Net Sales				Net Sales
		Quarter Ended				Year to Date Ended
		30-Sep-14		28-Sep-13		30-Sep-14		28-Sep-13
	North America (primarily U.S.)	$	117,796	$	109,810	$	370,944	$	343,844

	Europe	64,116		52,315		199,196		160,895

	Asia and other	20,608		13,318		57,716		36,949

	Total	$	202,520	$	175,443	$	627,856	$	541,688

	Net sales to third parties are attributed to the geographic regions based on the country in which the shipment originates.
	The net assets of the Company’s foreign subsidiaries at September 30, 2014 and December 31, 2013 were $143.2 million and $138.7 million, respectively.

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2014
Restructuring and Related Activities [Abstract]	'
Restructuring	'
	Restructuring
	In the quarter ended December 31, 2012, the Company adopted a restructuring plan (“2012 Altra Plan”) as a result of continued sluggish demand in Europe and general global economic conditions. The actions taken pursuant to the 2012 Altra Plan included reducing headcount and limiting discretionary spending to improve profitability in Europe. The Company did not record any restructuring charges associated with the 2012 Altra Plan in the year to date period ended September 30, 2014.
	In the quarter ended September 30, 2014, the Company adopted a restructuring plan (“2014 Altra Plan”) as a result of weak demand in Europe and to make certain adjustments to its existing sales force to reflect the Company's expanding global footprint. The actions taken pursuant to the 2014 Altra Plan included reducing headcount and limiting discretionary spending to improve profitability.
	The Company’s total restructuring expense, by major component for the quarter and year to date periods ended September 30, 2014 and September 28, 2013 was as follows:



		Quarter Ended						Year to Date Ended
		30-Sep-14			28-Sep-13			30-Sep-14		28-Sep-13
		2014			2012			2014		2012
		Altra Plan			Altra Plan			Altra Plan		Altra Plan
	Severance	$	1,161		$	137		$	1,161	$	653

	Other	482			(40		)	482		2

	Total cash expenses	$	1,643		$	97		$	1,643	$	655

	The following is a reconciliation of the accrued restructuring cost:


		All Plans
	Balance at January 1, 2014	$	429

	Restructuring expense incurred	1,643

	Cash payments	(933		)
	Balance at September 30, 2014	$	1,139

	The total restructuring reserve as of September 30, 2014 relates to severance costs to be paid to employees and is recorded in accruals and other current liabilities on the accompanying condensed consolidated balance sheet.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	General Litigation
	The Company is involved in various pending legal proceedings arising out of the ordinary course of business. These proceedings primarily involve commercial claims, product liability claims, personal injury claims, and workers’ compensation claims. None of these legal proceedings are expected to have a material adverse effect on the results of operations, cash flows, or financial condition of the Company. With respect to these proceedings, management believes that the Company will prevail, has adequate insurance coverage or has established appropriate reserves to cover potential liabilities. Any costs that management estimates may be paid related to these proceedings or claims are accrued when the liability is considered probable and the amount can be reasonably estimated. There can be no assurance, however, as to the ultimate outcome of any of these matters, and if all or substantially all of these legal proceedings were to be determined adversely to the Company, there could be a material adverse effect on the results of operations, cash flows, or financial condition of the Company. We have established loss provisions for matters in which losses are probable and can be reasonably estimated. There were no material amounts accrued in the accompanying condensed consolidated balance sheets for potential litigation as of September 30, 2014 or December 31, 2013. For matters where a reserve has not been established and for which we believe a loss is reasonably possible, as well as for matters where a reserve has been recorded but for which an exposure to loss in excess of the amount accrued is reasonably possible, we believe that such losses, individually and in the aggregate, will not have a material effect on our consolidated financial statements.

	The Company also risks exposure to product liability claims in connection with products it has sold and those sold by businesses that the Company acquired. Although in some cases third parties have retained responsibility for product liability claims relating to products manufactured or sold prior to the acquisition of the relevant business and in other cases the persons from whom the Company has acquired a business may be required to indemnify the Company for certain product liability claims subject to certain caps or limitations on indemnification, the Company cannot assure that those third parties will in fact satisfy their obligations with respect to liabilities retained by them or their indemnification obligations. If those third parties become unable to or otherwise do not comply with their respective obligations including indemnity obligations, or if certain product liability claims for which the Company is obligated were not retained by third parties or are not subject to these indemnities, the Company could become subject to significant liabilities or other adverse consequences. Moreover, even in cases where third parties retain responsibility for product liability claims or are required to indemnify the Company, significant claims arising from products that have been acquired could have a material adverse effect on the Company’s ability to realize the benefits from an acquisition, could result in the reduction of the value of goodwill that the Company recorded in connection with an acquisition, or could otherwise have a material adverse effect on the Company’s business, financial condition, or operations.

Subsequent_Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure.
	On October 22, 2014, the Company declared a cash dividend of $0.12 per share for the quarter ended December 31, 2014, payable on January 2, 2015 to shareholders of record as of December 18, 2014.

Changes_in_Accumulated_Other_C1

Changes in Accumulated Other Comprehensive Income (Loss) by Component (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Changes in Accumulated Other Comprehensive Income (Loss) by Component	'
	The following is a reconciliation of changes in Accumulated Other Comprehensive Income (Loss) by Component for the periods presented:



		Gains and		Defined			Cumulative			Total
		Losses on		Benefit			Foreign
		Cash Flow		Pension			Currency
		Hedges		Plans			Translation
							Adjustment
	Accumulated Other Comprehensive Income (Loss) by Component, January 1, 2013	$	—	$	(4,607	)	$	(18,796	)	$	(23,403	)

	Net current-period Other Comprehensive Income (Loss)	191		—			(46		)	145

	Accumulated Other Comprehensive Income (Loss) by Component, Balance at September 28, 2013	$	191	$	(4,607	)	$	(18,842	)	$	(23,258	)




		Gains and		Defined			Cumulative			Total
		Losses on		Benefit			Foreign
		Cash Flow		Pension			Currency
		Hedges		Plans			Translation
							Adjustment
	Accumulated Other Comprehensive Income (Loss) by Component, January 1, 2014	$	135	$	(3,133	)	$	(15,398	)	$	(18,396	)

	Net current-period Other Comprehensive Income (Loss)	109		—			(11,437		)	(11,328		)

	Accumulated Other Comprehensive Income (Loss) by Component, Balance at September 30, 2014	$	244	$	(3,133	)	$	(26,835	)	$	(29,724	)

Net_Income_per_Share_Tables

Net Income per Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Reconciliation of Basic to Diluted Net Income per Share	'
	The following is a reconciliation of basic to diluted net income per share:


		Quarter Ended				Year to Date Ended
		30-Sep-14		28-Sep-13		30-Sep-14		28-Sep-13
	Net income attributable to Altra Industrial Motion Corp.	$	6,946	$	10,501	$	31,108	$	33,070

	Shares used in net income per common share - basic	26,648		26,780		26,785		26,750

	Dilutive effect of the equity premium on Convertible Notes at the average price of common stock	626		—		687		—

	Incremental shares of unvested restricted common stock	60		56		85		102

	Shares used in net income per common share - diluted	27,334		26,836		27,557		26,852

	Earnings per share:
	Basic net income attributable to Altra Industrial Motion Corp.	$	0.26	$	0.39	$	1.16	$	1.24

	Diluted net income attributable to Altra Industrial Motion Corp.	$	0.25	$	0.39	$	1.13	$	1.23

Acquisitions_Tables

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2014
Svendborg [Member]	'
Preliminary Purchase Price Allocation as of Acquisition Date	'


		At Acquisition			Measurement			At Acquisition
		Date			Period			Date (As
					Adjustments			Adjusted)
	Purchase price, excluding acquisition costs of approximately $2.5 million	$	102,096		$	—		$	102,096

	Cash and cash equivalents	7,483			—			7,483

	Trade receivables	21,575			(809		)	20,766

	Inventories	25,452			(224		)	25,228

	Prepaid and other	5,511			(76		)	5,435

	Property, plant and equipment	12,216			—			12,216

	Other assets	1,133			—			1,133

	Intangible assets	48,893			—			48,893

	Total assets acquired	122,263			(1,109		)	121,154

	Accounts payable	4,833			—			4,833

	Accrued expenses and other current liabilities	9,620			168			9,788

	Taxes payable	10,254			—			10,254

	Deferred tax liability	11,483			—			11,483

	Total liabilities assumed	36,190			168			36,358

	Net assets acquired	86,073			(1,277		)	84,796

	Excess of purchase price over fair value of net assets acquired	$	16,023		$	1,277		$	17,300

Amounts Recorded as Intangible Assets	'

Proforma Amount on Acquisition Occurred	'
	These pro forma amounts do not purport to be indicative of the results that would have actually been obtained if the acquisition occurred at the beginning of the period or that may be obtained in the future.



		Pro Forma				Pro Forma
		(unaudited)				(unaudited)
		Quarter Ended				Year to Date Period Ended
			28-Sep-13			30-Sep-14		28-Sep-13
	Total revenues		$	201,405		$	633,762	$	615,885

	Net income attributable to Altra Industrial Motion Corp.		$	12,777		$	31,852	$	39,799

	Basic earnings per share:
	Net income attributable to Altra Industrial Motion Corp.		$	0.48		$	1.19	$	1.49

	Diluted earnings per share:
	Net income attributable to Altra Industrial Motion Corp.		$	0.48		$	1.16	$	1.48

GuardianAcquisition [Member]	'
Amounts Recorded as Intangible Assets	'

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Summary of Inventories	'
	Inventories located at certain subsidiaries are stated at the lower of cost or market, principally using the last-in, first-out (“LIFO”) method. Inventories at September 30, 2014 and December 31, 2013 consisted of the following:


		30-Sep-14		31-Dec-13
	Raw materials	$	40,545	$	56,824

	Work in process	16,352		18,432

	Finished goods	78,486		68,409

		$	135,383	$	143,665

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Changes in Goodwill	'
	Changes to goodwill from January 1, through September 30, 2014 were as follows:


		2014
	Gross goodwill balance as of January 1	$	136,149

	Impact of changes in foreign currency	(3,048		)
	Adjustment related to the impact of Guardian (See Note 6)	2,085

	Measurement period adjustments related to acquisition of Svendborg (See Note 6)	1,277

	Gross goodwill balance as of September 30,	136,463

	Accumulated impairment as of January 1	(31,810		)
	Impairment charge during the period	—

	Accumulated impairment as of September 30,	(31,810		)
	Net goodwill balance September 30,	$	104,653

Other Intangible Assets	'
	Other intangible assets as of September 30, 2014 and December 31, 2013 consisted of the following:


		30-Sep-14					31-Dec-13
		Cost			Accumulated		Cost			Accumulated
					Amortization					Amortization
	Other intangible assets
	Intangible assets not subject to amortization:
	Tradenames and trademarks	$	43,635		$	—	$	42,985		$	—

	Intangible assets subject to amortization:
	Customer relationships	126,364			49,400		118,914			42,645

	Product technology and patents	6,062			5,848		6,062			5,719

	Impact of changes in foreign currency	(5,283		)	—		(829		)	—

	Total intangible assets	$	170,778		$	55,248	$	167,132		$	48,364

Warranty_Costs_Tables

Warranty Costs (Tables)	9 Months Ended
	Sep. 30, 2014
Guarantees [Abstract]	'
Changes in Carrying Amount of Accrued Product Warranty Costs	'
	Changes in the carrying amount of accrued product warranty costs for each of the year to date periods ended September 30, 2014 and September 28, 2013 are as follows:


		30-Sep-14			28-Sep-13
	Balance at beginning of period	$	8,739		$	5,625

	Accrued current period warranty expense	1,314			1,758

	Payments	(1,900		)	(1,743		)
	Balance at end of period	$	8,153		$	5,640

Pension_and_Other_Employee_Ben1

Pension and Other Employee Benefits (Tables)	9 Months Ended
	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Reconciliation of Benefit Obligation, Fair Value of Plan Assets and Funded Status of Respective Defined Benefit (Pension) and Postretirement Benefit Plans	'
	The following tables represent the reconciliation of the net periodic benefit cost of the defined benefit (pension) plans as of September 30, 2014 and September 28, 2013:



		Quarter Ended
		Pension Benefits
		30-Sep-14			28-Sep-13
	Service cost	$	38		$	37

	Interest cost	273			246

	Expected return on plan assets	(269		)	(267		)
	Amortization of net gain	27			41

	Net periodic benefit cost (income)	$	69		$	57




		Year to Date Ended
		Pension Benefits
		30-Sep-14			28-Sep-13
	Service cost	$	114		$	113

	Interest cost	819			738

	Expected return on plan assets	(807		)	(801		)
	Amortization of net gain	81			125

	Net periodic benefit cost (income)	$	207		$	175

Debt_Tables

Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Outstanding Debt Obligations	'
	Outstanding debt obligations at September 30, 2014 and December 31, 2013 were as follows:



		30-Sep-14				31-Dec-13
	Debt:
	Revolving Credit Facility	$	37,000			$	41,198

	Convertible Notes	85,000				85,000

	Term Loan Facility	137,528				163,245

	Equipment Loan	5,334				4,155

	Mortgages	340				659

	Capital leases	—				178

	Other	28				—

	Total debt	265,230				294,435

	Less: debt discount, net of accretion	(13,636		)		(16,163		)
	Total debt, net of unaccreted discount	$	251,594			$	278,272

	Less current portion of long-term debt	14,532				16,924

	Total long-term debt, net of unaccreted discount	$	237,062			$	261,348

Carrying Amount of Debt	'
	The carrying amount of the principal amount of the liability component, the unamortized discount, and the net carrying amount are as follows as of September 30, 2014:



	Principal amount of debt	$	85,000

	Unamortized discount	13,636

	Carrying value of debt	$	71,364

Interest Expense Associated with Convertible Notes	'
	Interest expense associated with the Convertible Notes consists of the following:



		Quarter to Date Ended
		30-Sep-14			28-Sep-13

	Contractual coupon rate of interest	$	584		$	584

	Accretion of Convertible Notes discount and amortization of deferred financing costs	681			879

	Interest expense for the convertible notes	$	1,265		$	1,463




		Year to Date Ended
		30-Sep-14			28-Sep-13

	Contractual coupon rate of interest	$	1,753		$	1,753

	Accretion of Convertible Notes discount and amortization of deferred financing costs	2,527			2,594

	Interest expense for the convertible notes	$	4,280		$	4,347

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2014
Equity [Abstract]	'
Company's Restricted Stock Grants	'
	The following table sets forth the activity of the Company’s restricted stock and performance share grants in the year to date period ended September 30, 2014:


		Shares		Weighted-average
				grant date fair value
	Shares unvested January 1, 2014	149,635		$	23.02

	Shares granted	132,441		33.56

	Shares for which restrictions lapsed	(122,898	)	29.5

	Shares unvested September 30, 2014	159,178		$	28.53

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2014

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Summary of Swaps Recognized in Other Long-term Assets and in Other Comprehensive Income (Loss)

The fair value of the swap recognized in other non-current assets, net and in other comprehensive income (loss) is as follows:

Fair Value

Notional

30-Sep-14

31-Dec-13

Effective Date

Amount

Fixed Rate

Maturity

April 30, 2013

85,000

0.626

30-Nov-16

243

213

Concentrations_of_Credit_Segme1

Concentrations of Credit, Segment Data and Workforce (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Net Sales to Third Parties by Geographic Region	'
	Net sales to third parties by geographic region are as follows:


		Net Sales				Net Sales
		Quarter Ended				Year to Date Ended
		30-Sep-14		28-Sep-13		30-Sep-14		28-Sep-13
	North America (primarily U.S.)	$	117,796	$	109,810	$	370,944	$	343,844

	Europe	64,116		52,315		199,196		160,895

	Asia and other	20,608		13,318		57,716		36,949

	Total	$	202,520	$	175,443	$	627,856	$	541,688

Restructuring_Tables

Restructuring (Tables)	9 Months Ended
	Sep. 30, 2014
Restructuring and Related Activities [Abstract]	'
Summary of Total Restructuring Expense	'
	The Company’s total restructuring expense, by major component for the quarter and year to date periods ended September 30, 2014 and September 28, 2013 was as follows:



		Quarter Ended						Year to Date Ended
		30-Sep-14			28-Sep-13			30-Sep-14		28-Sep-13
		2014			2012			2014		2012
		Altra Plan			Altra Plan			Altra Plan		Altra Plan
	Severance	$	1,161		$	137		$	1,161	$	653

	Other	482			(40		)	482		2

	Total cash expenses	$	1,643		$	97		$	1,643	$	655

Reconciliation of Accrued Restructuring Costs	'
	The following is a reconciliation of the accrued restructuring cost:


		All Plans
	Balance at January 1, 2014	$	429

	Restructuring expense incurred	1,643

	Cash payments	(933		)
	Balance at September 30, 2014	$	1,139

Organization_and_Nature_of_Ope1

Organization and Nature of Operations - Additional Information (Detail) (Brand [Member])	9 Months Ended
	Sep. 30, 2014
	Country
	Product
Brand [Member]	'
Organization And Nature Of Business [Line Items]	'
Number of product lines	42
Number of countries in which the company has production facilities	11

Basis_of_Presentation_Addition

Basis of Presentation - Additional Information (Detail)	Jul. 11, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Percentage of ownership acquired	85.00%

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Convertible Notes [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Interest on notes	2.75%	2.75%
Carrying amount of financial instruments	$85,000,000	$85,000,000
Estimated fair value of financial instruments	102,800,000	116,500,000
Money Market Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash and cash equivalents	$300,000	$16,600,000

Changes_in_Accumulated_Other_C2

Changes in Accumulated Other Comprehensive Income (Loss) by Component - Changes in Accumulated Other Comprehensive Income (Loss) by Component (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Accumulated other comprehensive income (loss) by component, beginning balance	'	'	($18,396)	($23,403)
Net current-period other comprehensive income (loss)	-12,112	-7,073	-11,328	145
Accumulated other comprehensive income (loss) by component, ending balance	-29,724	-23,258	-29,724	-23,258
Gains and Losses on Cash Flow Hedges [Member]	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Accumulated other comprehensive income (loss) by component, beginning balance	'	'	135	0
Net current-period other comprehensive income (loss)	'	'	109	191
Accumulated other comprehensive income (loss) by component, ending balance	244	191	244	191
Defined Benefit Pension Plans [Member]	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Accumulated other comprehensive income (loss) by component, beginning balance	'	'	-3,133	-4,607
Net current-period other comprehensive income (loss)	'	'	0	0
Accumulated other comprehensive income (loss) by component, ending balance	-3,133	-4,607	-3,133	-4,607
Cumulative Foreign Currency Translation Adjustment [Member]	'	'	'	'
Accumulated Other Comprehensive Income (Loss) [Line Items]	'	'	'	'
Accumulated other comprehensive income (loss) by component, beginning balance	'	'	-15,398	-18,796
Net current-period other comprehensive income (loss)	'	'	-11,437	-46
Accumulated other comprehensive income (loss) by component, ending balance	($26,835)	($18,842)	($26,835)	($18,842)

Net_Income_per_Share_Reconcili

Net Income per Share - Reconciliation of Basic to Diluted Net Income per Share (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Earnings Per Share [Abstract]	'	'	'	'
Net income attributable to Altra Industrial Motion Corp.	$6,946	$10,501	$31,108	$33,070
Shares used in net income per common share - basic	26,648	26,780	26,785	26,750
Dilutive effect of the equity premium on Convertible Notes at the average price of common stock	626	0	687	0
Incremental shares of unvested restricted common stock	60	56	85	102
Shares used in net income per common share - diluted	27,334	26,836	27,557	26,852
Earnings per share:	'	'	'	'
Basic net income attributable to Altra Industrial Motion Corp. (in usd per share)	$0.26	$0.39	$1.16	$1.24
Diluted net income attributable to Altra Industrial Motion Corp. (in usd per share)	$0.25	$0.39	$1.13	$1.23

Net_Income_per_Share_Additiona

Net Income per Share - Additional Information (Detail) (USD $)	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Current conversion price per share of convertible notes	$26.82

Acquisitions_Additional_Inform

Acquisitions - Additional Information (Detail)	9 Months Ended		12 Months Ended	9 Months Ended	0 Months Ended	1 Months Ended			9 Months Ended	0 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Dec. 17, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 17, 2013	Sep. 30, 2014	Jul. 01, 2014
	USD ($)	EUR (€)	Country	Customer Relationships [Member]	Svendborg [Member]	Svendborg [Member]	Svendborg [Member]	Svendborg [Member]	Svendborg [Member]	GuardianAcquisition [Member]
					USD ($)	USD ($)	EUR (€)	USD ($)	Customer Relationships [Member]	USD ($)
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'	'	'
Business acquisition cash consideration	'	'	'	'	'	$110.20	€ 80.10	'	'	'
Cash remaining on the balance sheet upon closing the acquisition	'	'	'	'	'	7.5	5.4	'	'	'
Business acquisition number of countries in which entity operates	'	'	7	'	'	'	'	'	'	'
Escrow deposits established for transfer pricing claims	'	'	'	'	'	11.6	8.5	'	'	'
Estimated liability for transfer pricing claims by the company	'	'	'	'	'	8.1	'	'	'	'
payment of transfer	8.1	5.9	'	'	'	'	'	'	'	'
Estimated receivables from transfer pricing claims by the company	'	'	'	'	'	'	'	8.1	'	'
Estimated useful lives	'	'	'	'14 years	'	'	'	'	'17 years	'
Approximate excluded acquisition costs of purchase price	'	'	'	'	$2.50	'	'	'	'	$0.40

Acquisitions_Preliminary_Purch

Acquisitions - Preliminary Purchase Price Allocation as of Acquisition Date (Detail) (USD $)	0 Months Ended				0 Months Ended
	Dec. 17, 2013	Dec. 17, 2013	Dec. 17, 2013	Dec. 17, 2013	Jul. 01, 2014	Jul. 01, 2014
	Svendborg [Member]	Svendborg [Member]	At Acquisition Date [Member]	Measurement Period Adjustments [Member]	GuardianAcquisition [Member]	GuardianAcquisition [Member]
			Svendborg [Member]	Svendborg [Member]
Business Acquisition [Line Items]	'	'	'	'	'	'
Business acquisition cash transfered	'	'	'	'	$17,100,000	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets	'	'	'	'	'	9,200,000
Purchase price, excluding acquisition costs of approximately $2.5 million	'	102,096,000	102,096,000	0	'	'
Cash and cash equivalents	'	7,483,000	7,483,000	0	'	2,012,000
Trade receivables	'	20,766,000	21,575,000	-809,000	'	4,000,000
Inventories	'	25,228,000	25,452,000	-224,000	'	'
Prepaid and other	'	5,435,000	5,511,000	-76,000	'	'
Property, plant and equipment	'	12,216,000	12,216,000	0	'	'
Other assets	'	1,133,000	1,133,000	0	'	'
Intangible assets	'	48,893,000	48,893,000	0	'	'
Total assets acquired	'	121,154,000	122,263,000	-1,109,000	'	'
Accounts payable	'	4,833,000	4,833,000	0	'	'
Accrued expenses and other current liabilities	'	9,788,000	9,620,000	168,000	'	200,000
Taxes payable	'	10,254,000	10,254,000	0	'	'
Deferred tax liability	'	11,483,000	11,483,000	0	'	'
Total liabilities assumed	'	36,358,000	36,190,000	168,000	'	'
Net assets acquired	'	84,796,000	86,073,000	-1,277,000	'	'
Excess of purchase price over fair value of net assets acquired	'	17,300,000	16,023,000	1,277,000	'	2,085,000
Approximate excluded acquisition costs of purchase price	$2,500,000	'	'	'	$400,000	'

Acquisitions_Amounts_Recorded_

Acquisitions - Amounts Recorded as Intangible Assets (Detail) (USD $)	Dec. 17, 2013	Sep. 30, 2014	Sep. 30, 2014
In Thousands, unless otherwise specified	Svendborg [Member]	Customer Relationships [Member]	Customer Relationships [Member]
			Svendborg [Member]
Intangible Asset Excluding Goodwill [Line Items]	'	'	'
Finite-Lived Intangible Asset, Useful Life	'	'14 years	'17 years
Total intangible assets	$48,893	'	'

Acquisitions_Proforma_Amount_o

Acquisitions - Proforma Amount on Acquisition Occurred (Detail) (USD $)	3 Months Ended	9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Business Combinations [Abstract]	'	'	'
Total revenues	$201,405	$633,762	$615,885
Net income attributable to Altra Industrial Motion Corp.	$12,777	$31,852	$39,799
Basic earnings per share:	'	'	'
Net income attributable to Altra Industrial Motion Corp.	$0.48	$1.19	$1.49
Diluted earnings per share:	'	'	'
Net income attributable to Altra Industrial Motion Corp.	$0.48	$1.16	$1.48

Inventories_Summary_of_Invento

Inventories - Summary of Inventories (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]	'	'
Raw materials	$40,545	$56,824
Work in process	16,352	18,432
Finished goods	78,486	68,409
Inventories, net	$135,383	$143,665

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	9 Months Ended			3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 28, 2013	Sep. 28, 2013
	Sep. 30, 2014	Inventory Valuation by LIFO Method [Member]	Inventory Valuation by LIFO Method [Member]	Inventory Valuation Provision [Member]	Inventory Valuation Provision [Member]
Inventory [Line Items]	'	'	'	'	'
Portion of total inventory valued by LIFO method	'	6.70%	7.50%	'	'
Inventory, LIFO Reserve, Effect on Income, Net	$300,000	'	'	'	'
Provision for valuation of sales component	'	'	'	$0	$0

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets - Changes in Goodwill (Detail) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'	'	'
Gross goodwill, begining balance	'	$136,149	'
Impact of changes in foreign currency	'	-3,048	'
Measurement period adjustments related to acquisition of Svendborg (See Note 6)	2,085	1,277	'
Gross goodwill, ending balance	136,463	136,463	'
Accumulated impairment, begining balance	'	-31,810	'
Impairment charge during the period	'	0	'
Accumulated impairment, ending balance	-31,810	-31,810	'
Net goodwill balance June 30	$104,653	$104,653	$104,339

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Other Intangible Assets (Detail) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]	'	'
Impact of changes in foreign currency, Cost	($5,283)	($829)
Total intangible assets, Cost	170,778	167,132
Total intangible assets, Accumulated Amortization	55,248	48,364
Tradenames and Trademarks [Member]	'	'
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]	'	'
Intangible assets not subject to amortization, Cost	43,635	42,985
Customer Relationships [Member]	'	'
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]	'	'
Intangible assets subject to amortization, Cost	126,364	118,914
Total intangible assets, Accumulated Amortization	49,400	42,645
Product Technology and Patents [Member]	'	'
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]	'	'
Intangible assets subject to amortization, Cost	6,062	6,062
Total intangible assets, Accumulated Amortization	$5,848	$5,719

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Goodwill And Intangible Assets [Line Items]	'	'	'	'
Amortization expense	$2,300,000	$1,700,000	$6,884,000	$4,882,000
Estimated Amortization Expense for Intangible Assets [Member]	'	'	'	'
Goodwill And Intangible Assets [Line Items]	'	'	'	'
Remainder 2014	2,400,000	'	2,400,000	'
Each of the next four years after 2014	9,300,000	'	9,300,000	'
Year 2015	9,200,000	'	9,200,000	'
Year 2016	9,200,000	'	9,200,000	'
Year 2017	9,200,000	'	9,200,000	'
Year 2018	9,200,000	'	9,200,000	'
Thereafter	$32,300,000	'	$32,300,000	'

Warranty_Costs_Additional_Info

Warranty Costs - Additional Information (Detail)	9 Months Ended
Warranty Costs - Additional Information (Detail)	Sep. 30, 2014
Maximum [Member]	'
Guarantor Obligations [Line Items]	'
Product warranty period	'2 years
Minimum [Member]	'
Guarantor Obligations [Line Items]	'
Product warranty period	'3 months

Warranty_Costs_Changes_in_Carr

Warranty Costs - Changes in Carrying Amount of Accrued Product Warranty Costs (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013
Guarantees [Abstract]	'	'
Balance at beginning of period	$8,739	$5,625
Accrued current period warranty expense	1,314	1,758
Payments	-1,900	-1,743
Balance at end of period	$8,153	$5,640

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'	'
Accrued interest and penalties	$0.20	$0.40

Pension_and_Other_Employee_Ben2

Pension and Other Employee Benefits - Reconciliation of Benefit Obligation, Fair Value of Plan Assets and Funded Status of Respective Defined Benefit (Pension) and Postretirement Benefit Plans (Detail) (Pension Benefits [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Pension Benefits [Member]	'	'	'	'
Pension Plans, Postretirement and Other Employee Benefits [Line Items]	'	'	'	'
Service cost	$38	$37	$114	$113
Interest cost	273	246	819	738
Expected return on plan assets	-269	-267	-807	-801
Amortization of net gain	27	41	81	125
Net periodic benefit cost (income)	$69	$57	$207	$175

Pension_and_Other_Employee_Ben3

Pension and Other Employee Benefits - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Minimum cash contribution to pension plan	$0.20

Debt_Outstanding_Debt_Obligati

Debt - Outstanding Debt Obligations (Detail)

9 Months Ended

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

USD ($)

EUR (€)

USD ($)

Revolving Credit Facility [Member]

Convertible Notes [Member]

Term Loan Facility [Member]

Equipment Loan [Member]

Mortgages [Member]

Capital Leases [Member]

Other [Member]

USD ($)

EUR (€)

USD ($)

Debt Instrument [Line Items]

Construction Loan

$7,900,000

€ 6,000,000

Total debt

265,230,000

294,435,000

37,000,000

41,198,000

85,000,000

137,528,000

163,245,000

5,334,000

4,155,000

340,000

659,000

178,000

28,000

Less: debt discount, net of accretion

-13,636,000

-16,163,000

Total debt, net of unaccreted discount

251,594,000

278,272,000

Less current portion of long-term debt

14,532,000

16,924,000

Total long-term debt, net of unaccreted discount

237,062,000

261,348,000

interest rate mortgage

2.50%

Debt Instrument, Periodic Payment, Interest

$300,000

€ 200,000

Debt_Additional_Information_De

Debt - Additional Information (Detail)

9 Months Ended

1 Months Ended

9 Months Ended

0 Months Ended

12 Months Ended

9 Months Ended

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Sep. 01, 2011

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

USD ($)

Initial Conversion Price [Member]

Additional Term Loan [Member]

Revolving Credit Facility [Member]

Minimum [Member]

Maximum [Member]

Convertible Debt [Member]

Convertible Notes [Member]

Term Loan Facility [Member]

Revolving Credit Agreement [Member]

Equipment And Working Capital Notes [Member]

Mortgages [Member]

Capital Leases [Member]

USD ($)

EUR (€)

USD ($)

Eurodollar Loan [Member]

ABR Based Loans [Member]

USD ($)

Eurodollar Loan [Member]

ABR Based Loans [Member]

USD ($)

CNY

Minimum [Member]

Maximum [Member]

USD ($)

EUR (€)

USD ($)

EUR (€)

USD ($)

Debt Instrument [Line Items]

Availability under credit facility agreement

$94,375,000,000

€ 50,000,000

$100,000,000

$200,000,000

Aggregate additional term loans

150,000,000

Credit facility maturity date

'December 6, 2018

Debt instrument, maturity date

1-Mar-31

6-Dec-18

Applicable margins for loans

1.38%

0.38%

1.88%

0.88%

Outstanding on revolving credit facility

37,000,000

41,200,000

Letters of credit outstanding

10,100,000

9,800,000

Amount available under credit facility

149,000,000

152,900,000

Percentage of capital stock not included in collateral

65.00%

Coupon interest rate

2.75%

Proceeds from the offering

81,300,000

Adjustment of shares

36.0985

Principal amount of notes

1,000

Conversion price per share

$26.82

$27.70

Percentage of sale price of common stock

130.00%

Consecutive trading days

'30 days

'20 days

Number of business day period

'5 days

Number of consecutive trading days in measurement period

'10 days

Percentage of measurement period

97.00%

Percentage of convertible notes redeemable

100.00%

Convertible notes redeemable period one

1-Mar-18

Convertible notes redeemable period two

1-Mar-21

Convertible notes redeemable period three

1-Mar-26

Conversion price redemption exceed

130.00%

Total debt

85,000,000

200,000

Debt component in note payable

60,500,000

Equity component in note payable

24,500,000

Discount rate for debt component

8.25%

Debt issuance cost

3,700,000

Adjustments to additional paid-in capital of convertible debt

1,000,000

Debt issuance cost, amortized

2,700,000

Effective interest rate of Senior Secured Notes

8.50%

Outstanding letters of credit

90.00%

Available to borrow loan amount

6,300,000

38,700,000

Interest rate

5.04%

8.02%

2.90%

Line of credit outstanding loan amount

5,300,000

32,800,000

Description about maturity date of debt instrument

'The note is due in installments from 2014 through 2016

Mortgage remaining principal balance

300,000

200,000

700,000

500,000

Borrowings under overdraft agreements

Approximated capital lease obligations

$200,000

Debt_Carrying_Amount_of_Debt_D

Debt - Carrying Amount of Debt (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Total long-term debt, net of unaccreted discount	$237,062	$261,348
Convertible Debt [Member]	'	'
Debt Instrument [Line Items]	'	'
Principal amount of debt	85,000	'
Unamortized discount	13,636	'
Total long-term debt, net of unaccreted discount	$71,364	'

Debt_Interest_Expense_Associat

Debt - Interest Expense Associated with Convertible Notes (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Debt Disclosure [Abstract]	'	'	'	'
Contractual coupon rate of interest	$584	$584	$1,753	$1,753
Accretion of Convertible Notes discount and amortization of deferred financing costs	681	879	2,527	2,594
Interest expense for the convertible notes	$1,265	$1,463	$4,280	$4,347

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended		0 Months Ended			9 Months Ended
	31-May-14	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013	Dec. 18, 2014	Oct. 22, 2014	Oct. 02, 2014	Sep. 30, 2014
	31-May-14	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013	Subsequent Event [Member]	Subsequent Event [Member]	Subsequent Event [Member]	Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'	'	'
Cash dividend	'	$0.12	$0.10	$0.34	$0.28	'	$0.12	'	'
Payments of Ordinary Dividends, Common Stock	'	'	'	'	'	'	'	$3,200,000	'
Payments of Dividends	'	'	'	8,644,000	4,852,000	'	'	'	'
Dividend paid	'	3,200,000	'	3,200,000	'	'	'	'	'
Dividend paid date	'	'	'	'	'	'	'	2-Oct-14	'
Dividends payable date of record	'	'	'	'	'	18-Dec-14	'	'	'
Stock repurchase program, authorized amount	50,000,000	'	'	'	'	'	'	'	'
Repurchase of common stock, shares	'	300,984	'	'	'	'	'	'	'
Treasury stock acquired, average cost per share	'	$32.91	'	'	'	'	'	'	'
Stock repurchase program, remaining authorized repurchase amount	'	37,200,000	'	'	'	'	'	'	'
Restricted shares for vesting period	'	'	'	'	'	'	'	'	'5 years
Compensation expense	'	800,000	900,000	2,600,000	2,400,000	'	'	'	'
Unrecognized compensation cost	'	4,200,000	'	4,200,000	'	'	'	'	'
Weighted average remaining period	'	'	'	'3 years	'	'	'	'	'
Fair market value of the shares	'	$600,000	'	'	'	'	'	'	'

Stockholders_Equity_Companys_U

Stockholders' Equity - Company's Unvested Restricted Stock Grants (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Shares unvested, beginning balance	149,635
Shares granted	132,441
Shares for which restrictions lapsed	-122,898
Shares unvested, ending balance	159,178
Weighted-average grant date fair value, beginning balance	$23.02
Weighted-average grant date fair value, Shares granted	$33.56
Weighted-average grant date fair value, Shares for which restrictions lapsed	$29.50
Weighted-average grant date fair value, ending balance	$28.53

Stockholders_Equity_Dividends_

Stockholders' Equity Dividends (Details) (USD $)	Sep. 30, 2014
In Millions, unless otherwise specified	Sep. 30, 2014
Dividends Payable [Line Items]	'
Dividends Payable	$3.20

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Apr. 30, 2013
	Sep. 30, 2014	Interest Rate Swap [Member]	Interest Rate Swap [Member]
Debt Instrument [Line Items]	'	'	'
Outstanding borrowings	'	$85,000,000	$85,000,000
Fixed Rate	'	0.63%	0.63%
Ineffectiveness associated with the swap	$0	'	'

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Summary of Swaps Recognized in Other Long-term Assets and in Other Comprehensive Income (Loss) (Detail) (Interest Rate Swap [Member], USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Apr. 30, 2013
Interest Rate Swap [Member]	'	'	'
Derivative [Line Items]	'	'	'
Effective Date	30-Apr-13	'	'
Notional Amount	$85,000,000	'	$85,000,000
Fixed Rate	0.63%	'	0.63%
Maturity	30-Nov-16	'	'
Fair Value	$243,000	$213,000	'

Concentrations_of_Credit_Segme2

Concentrations of Credit, Segment Data and Workforce - Additional Information (Detail) (USD $)	9 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 28, 2013
	Segment		Sales [Member]	Sales [Member]
			Customer	Customer
Concentration Risk [Line Items]	'	'	'	'
Sales contract payments due period	'30 days	'	'	'
Maximum revenue percentage from any one customer	'	'	10.00%	10.00%
Number of customers representing over 10% of total sales	'	'	0	0
Number of operating segments	3	'	'	'
Number of reportable segments	1	'	'	'
Number of operating segments expected to have similar long-term average gross profit margins	3	'	'	'
Net assets of foreign subsidiaries	$143.20	$138.70	'	'

Concentrations_of_Credit_Segme3

Concentrations of Credit, Segment Data and Workforce - Net Sales to Third Parties by Geographic Region (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Concentration Risk [Line Items]	'	'	'	'
Net sales	$202,520	$175,443	$627,856	$541,688
North America (Primarily U.S.) [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Net sales	117,796	109,810	370,944	343,844
Europe [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Net sales	64,116	52,315	199,196	160,895
Asia and Other [Member]	'	'	'	'
Concentration Risk [Line Items]	'	'	'	'
Net sales	$20,608	$13,318	$57,716	$36,949

Restructuring_Summary_of_Total

Restructuring - Summary of Total Restructuring Expense (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Total cash expenses	$1,643	$97	$1,643	$655
2012 Altra Plan [Member]	'	'	'	'
Restructuring Cost and Reserve [Line Items]	'	'	'	'
Severance	1,161	137	1,161	653
Other	482	-40	482	2
Total cash expenses	$1,643	$97	$1,643	$655

Restructuring_Reconciliation_o

Restructuring - Reconciliation of Accrued Restructuring Costs (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013
Restructuring and Related Activities [Abstract]	'	'	'	'
Beginning Balance	'	'	$429	'
Restructuring expense incurred	1,643	97	1,643	655
Cash payments	'	'	-933	'
Ending Balance	$1,139	'	$1,139	'

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]	'	'
Potential litigation	$0	$0

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended
	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013	Jan. 02, 2015	Dec. 18, 2014	Oct. 22, 2014
	Sep. 30, 2014	Sep. 28, 2013	Sep. 30, 2014	Sep. 28, 2013	Subsequent Event [Member]	Subsequent Event [Member]	Subsequent Event [Member]
Subsequent Event [Line Items]	'	'	'	'	'	'	'
Dividend declared date	'	'	'	'	'	'	22-Oct-14
Dividend per share	$0.12	$0.10	$0.34	$0.28	'	'	$0.12
Dividend payable date	'	'	'	'	2-Jan-15	'	'
Dividend record date	'	'	'	'	'	18-Dec-14	'