Altra Industrial Motion (AIMC) 10-K 26 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 23, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Entity Registrant Name	ALTRA INDUSTRIAL MOTION CORP.
Entity Central Index Key	1374535
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		26,419,588
Entity Public Float			$950

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$47,503	$63,604
Trade receivables, less allowance for doubtful accounts of $2,302 and $2,245 at December 31, 2014 and 2013, respectively	106,458	109,084
Inventories	132,736	143,665
Deferred income taxes	9,240	9,754
Income tax receivable	6,247	5,032
Prepaid expenses and other current assets	8,617	18,066
Total current assets	310,801	349,205
Property, plant and equipment, net	156,366	157,535
Intangible assets, net	110,730	118,768
Goodwill	102,087	104,339
Deferred income taxes	987	934
Other non-current assets, net	3,592	4,895
Total assets	684,563	735,676
Current liabilities:
Accounts payable	44,298	51,180
Accrued payroll	23,254	23,983
Accruals and other current liabilities	33,591	34,979
Income tax payable	3,189	12,963
Deferred income taxes	120	44
Current portion of long-term debt	15,176	16,924
Total current liabilities	119,628	140,073
Long-term debt — less current portion and net of unaccreted discount	240,576	261,348
Deferred income taxes	53,226	53,813
Pension liabilities	9,993	8,025
Long-term taxes payable	629	1,038
Other long-term liabilities	869	1,055
Redeemable non-controlling interest	883	991
Commitments and Contingencies (Note 14)
Stockholders’ equity:
Preferred stock ($0.0001 par value, 10,000,000 shares authorized, none issued and outstanding at December 31, 2014 and 2013, respectively)	0	0
Common stock ($0.001 par value, 90,000,000 shares authorized, 26,353,755 and 26,819,795 issued and outstanding at December 31, 2014 and 2013, respectively)	26	27
Additional paid-in capital	139,087	154,471
Retained earnings	161,061	133,231
Accumulated other comprehensive loss	-41,415	-18,396
Total stockholders’ equity	258,759	269,333
Total liabilities, non-controlling interest and stockholders’ equity	$684,563	$735,676

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$2,302	$2,245
Preferred Stock, par value (in usd per share)	$0.00	$0.00
Preferred Stock, shares authorized	10,000,000	10,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common stock, par value (in usd per share)	$0.00	$0.00
Common stock, shares authorized	90,000,000	90,000,000
Common stock, shares issued	26,353,755	26,819,795
Common stock, shares outstanding	26,353,755	26,819,795

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Net sales	$819,817	$722,218	$731,990
Cost of sales	570,948	506,837	513,442
Gross profit	248,869	215,381	218,548
Operating expenses:
Selling, general and administrative expenses	156,471	130,155	127,044
Research and development expenses	15,522	12,536	11,457
Restructuring costs	1,767	1,111	3,196
Total operating expenses	173,760	143,802	141,697
Income from operations	75,109	71,579	76,851
Other non-operating income and expense:
Interest expense, net	11,994	10,586	40,790
Other non-operating expense (income), net	3	-1,657	-1,702
Total other non-operating expense (income), net	11,991	12,243	42,492
Total	63,118	59,336	34,359
Provision for income taxes	22,936	19,151	10,154
Net income	40,182	40,185	24,205
Net (income) loss attributable to non-controlling interest	15	-90	-88
Net income attributable to Altra Industrial Motion Corp.	$40,167	$40,275	$24,293
Weighted average shares, basic	26,713	26,766	26,656
Weighted average shares, diluted	27,403	26,841	26,756
Earnings per share:
Basic net income attributable to Altra Industrial Motion Corp. (in usd per share)	$1.50	$1.50	$0.91
Diluted net income attributable to Altra Industrial Motion Corp. (in usd per share)	$1.47	$1.50	$0.91
Cash dividend declared (in usd per share)	$0.46	$0.38	$0.16

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$40,182	$40,185	$24,205
Other Comprehensive Income (loss):
Pension liability adjustment, net of tax	-1,685	1,474	-2,122
Change in fair value of interest rate swap, net of tax	8	135	0
Foreign currency translation adjustment, net of tax	-21,342	3,398	3,795
Total Comprehensive income	17,163	45,192	25,878
Comprehensive (income) loss attributable to non-controlling interest	-108	248	88
Comprehensive income attributable to Altra Industrial Motion Corp.	$17,055	$45,440	$25,966

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
Beginning Balance at Dec. 31, 2010
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (income) loss attributable to non-controlling interest						($88)
Ending Balance at Dec. 31, 2011	208,396	27	150,234	83,211	-25,076	0
Beginning Balance, Shares (in shares) at Dec. 31, 2011		26,600,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation and vesting of restricted stock	1,954	0	1,954
Stock based compensation and vesting of restricted stock (in shares)		124,000
Net income attributable to Altra Industrial Motion Corp.	24,293			24,293
Net (income) loss attributable to non-controlling interest	88
Fair value of non-controlling interest at acquisition						1,327
Dividends declared	-4,304			-4,304
Cumulative foreign currency translation adjustment, net of tax expense	3,795				3,795
Minimum Pension adjustment, net of tax expense	-2,122				-2,122
Ending Balance at Dec. 31, 2012	232,012	27	152,188	103,200	-23,403	1,239
Ending Balance, Shares (in shares) at Dec. 31, 2012		26,724,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation and vesting of restricted stock	2,283		2,283
Stock based compensation and vesting of restricted stock (in shares)		96,000
Net income attributable to Altra Industrial Motion Corp.	40,275			40,275
Net (income) loss attributable to non-controlling interest	90					-90
Dividends declared	-10,244			-10,244
Cumulative foreign currency translation adjustment, net of tax expense	3,398				3,398	-158
Minimum Pension adjustment, net of tax expense	1,474				1,474
Change in fair value of interest rate swap, net of tax expense	135				135
Ending Balance at Dec. 31, 2013	269,333	27	154,471	133,231	-18,396	991
Ending Balance, Shares (in shares) at Dec. 31, 2013		26,820,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock based compensation and vesting of restricted stock	2,233		2,233
Stock based compensation and vesting of restricted stock (in shares)		79,000
Net income attributable to Altra Industrial Motion Corp.	40,167			40,167
Net (income) loss attributable to non-controlling interest	-15					15
Dividends declared	-12,337			-12,337
Cumulative foreign currency translation adjustment, net of tax expense	-21,342				-21,342	-123
Minimum Pension adjustment, net of tax expense	-1,685				-1,685
Change in fair value of interest rate swap, net of tax expense	8				8
Repurchases of common stock (in shares)	-545,154	-545,154
Repurchases of common stock	-17,618	-1	-17,617
Ending Balance at Dec. 31, 2014	$258,759	$26	$139,087	$161,061	($41,415)	$883
Ending Balance, Shares (in shares) at Dec. 31, 2014		26,353,846

Consolidated_Statement_of_Stoc1

Consolidated Statement of Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Stockholders' Equity [Abstract]
Change in fair value of interest rate swap, tax expense		$78
Minimum Pension adjustment, tax expense	478	800	1,388
Tax expense for foreign currency	$203	$50	$994
Cash dividend declared (in usd per share)	$0.46	$0.38	$0.16

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities
Net income	$40,182	$40,185	$24,205
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation	23,118	21,419	20,537
Amortization of intangible assets	9,019	6,505	6,839
Amortization and write-offs of deferred loan costs	927	873	6,006
(Gain) loss on foreign currency, net	-157	742	-125
Amortization of inventory fair value adjustment	2,376	0	122
Accretion and write-off of debt discount and premium	3,407	3,143	4,869
(Gain) loss on disposal/impairment of fixed assets	-92	147	251
Provision (benefit) for deferred taxes	2,712	3,464	-625
Stock-based compensation	3,101	3,173	2,696
Changes in operating assets and liabilities:
Trade receivables	-1,050	5,791	836
Inventories	5,402	6,412	4,084
Accounts payable and accrued liabilities	-6,055	-708	-6,640
Other current assets and liabilities	860	2,156	726
Other operating assets and liabilities	749	-3,677	-3,863
Net cash provided by operating activities	84,499	89,625	59,918
Cash flows from investing activities
Purchase of property, plant and equipment	-28,050	-27,823	-31,346
Proceeds from sale of land	848	0	0
Net cash used in investing activities	-42,294	-130,005	-38,770
Cash flows from financing activities
Payment of debt issuance costs	0	-670	-2,454
Payments on term loan facility	-23,247	-5,625	0
Payments on revolving credit facility	-9,190	-59,304
Dividend payments	-15,033	-7,548	-4,304
Proceeds from Equipment Loan	2,870	2,999	1,100
Payments of equipment and working capital notes	-1,594	0	0
Borrowing under Revolving Credit Facility	8,000	21,198	0
Proceeds from Bauer mortgage	3,647	0	0
Borrowing under Additional Term Loan	0	68,871	0
Shares surrendered for tax withholding	-1,158	-1,174	-949
Payment on mortgages and other debt	-642	-756	-1,199
Common stock repurchase under share repurchase program	-17,618
Proceeds from Former Term Loan Facility and Revolving Credit Facility	0	0	179,304
Net payments on capital leases	0	0	-333
Net cash (used) provided by financing activities	-53,965	17,991	-29,880
Effect of exchange rate changes on cash and cash equivalents	-4,341	839	1,371
Net change in cash and cash equivalents	-16,101	-21,550	-7,361
Cash and cash equivalents at beginning of year	63,604	85,154	92,515
Cash and cash equivalents at end of period	47,503	63,604	85,154
Interest	7,618	6,704	30,891
Income taxes	31,631	13,398	12,397
Non-cash Financing and Investing:
Acquisition of property, plant and equipment included in accounts payable	1,642	1,179	574
Dividend accrued	0	2,696	0
Acquisition of property, plant and equipment through capital leases	1	0	0
San Marcos [Member]
Cash flows from financing activities
Redemption of variable rate demand revenue bonds related to the San Marcos Facility	0	0	-3,000
Mt Pleasant Facility (Member)
Cash flows from investing activities
Proceeds from sale of Mt. Pleasant Facility	0	578	0
Svendborg [Member]
Cash flows from investing activities
Acquisition, net of cash received	0	-94,613	0
Cash paid to escrow agent for Svendborg Transfer Pricing Claim liability	0	-8,147	0
Lamiflex [Member]
Cash flows from investing activities
Acquisition, net of cash received	0	0	-7,424
Bauer [Member]
Cash flows from investing activities
Acquisition, net of cash received	-15,092	0	0
Senior Secured Notes [Member]
Cash flows from financing activities
Purchase of 8 1/8% Senior Secured Notes	$0	$0	($198,045)

Consolidated_Statements_of_Cas1

Consolidated Statements of Cash Flows (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Guardian [Member]
Cash acquired from acquisition	$2,000
Svendborg [Member]
Cash acquired from acquisition		7,500
Lamiflex [Member]
Cash acquired from acquisition			$68

Description_of_Business_and_Su

Description of Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies
	Basis of Preparation and Description of Business
	Headquartered in Braintree, Massachusetts, Altra Industrial Motion Corp. (the “Company”) 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 twelve 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 former wholly owned subsidiary, changed its name to Altra Power Transmission, Inc. In December 2014, Altra Power Transmission, Inc. was merged into Altra Industrial Motion Corp.
	Principles of Consolidation
	The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
	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 equivalent shares 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:
		Year Ended December, 31
		2014		2013			2012
	Net income attributable to Altra Industrial Motion Corp.	$	40,167	$	40,275		$	24,293
	Shares used in net income per common share — basic	26,713		26,766			26,656
	Dilutive effect of the equity premium on Convertible Notes at the average price of common stock	612		—			—
	Incremental shares of unvested restricted common stock	78		75			100
	Shares used in net income per common share — diluted	27,403		26,841			26,756
	Earnings per share:
	Basic net income attributable to Altra Industrial Motion Corp.	$	1.5	$	1.5		$	0.91
	Diluted net income attributable to Altra Industrial Motion Corp.	$	1.47	$	1.5		$	0.91
	During the year ended December 31, 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 net income per share in the diluted earnings per share calculation above. The Company excluded 2,571,130 shares in 2014, 3,137,351 shares in 2013 and 3,094,706 shares in 2012 (amounts not in thousands) related to the Convertible Notes (See Note 9) from the above earnings per share calculation as these shares were anti-dilutive.
	Fair Value of Financial Instruments
	The carrying values of financial instruments, including accounts receivable, cash equivalents, accounts payable, and other accrued liabilities are carried at cost, which approximates fair value. Debt under the Company’s Credit Agreement with certain financial institutions including the Term Loan Facility of $133,697,000 and a Revolving Credit Facility of $200,000,000 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 $85.0 million at December 31, 2014 and 2013. The estimated fair value of the Convertible Notes at December 31, 2014 and 2013 was $99.0 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 December 31, 2014 and 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).
	The estimated fair value of the Company’s interest rate swap agreement with certain financial institutions (“Interest Rate Swap”) as of December 31, 2014 and 2013 was $0.1 million and $0.1 million , 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.
	Use of Estimates
	The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the financial statements. Actual results could differ from those estimates.
	Non-controlling Interest
	On July 11, 2012, the Company acquired 85% of privately held Lamiflex do Brasil Equipamentos Industriais Ltda. (“Lamiflex”).
	The Company recorded the redeemable non-controlling interest from its acquisition of an 85% ownership interest of Lamiflex at fair value at the date of acquisition. In connection with this acquisition, the Company entered into put and call option agreements with the minority shareholders for the potential purchase of the non-controlling interest at a future date at a value based on a contractually determined formula. As a result of the option agreements, the non-controlling interest is considered redeemable and is classified as temporary equity on the Company’s consolidated balance sheet. The non-controlling interest is reviewed at each subsequent reporting period and adjusted, as needed, to reflect its then redemption value.
	Foreign Currency Translation
	Assets and liabilities of subsidiaries operating outside of the United States with a functional currency other than the U.S. Dollar are translated into U.S. Dollars using exchange rates at the end of the respective period. Revenues and expenses are translated at average exchange rates effective during the respective period.
	Foreign currency translation adjustments are included in accumulated other comprehensive income as a separate component of stockholders’ equity. Net foreign currency transaction gains and losses are included in the results of operations in the period incurred and included in other non-operating expense (income), net in the accompanying statements of income.
	Trade Receivables
	An allowance for doubtful accounts is recorded for estimated collection losses that will be incurred in the collection of receivables. Estimated losses are based on historical collection experience, as well as a review by management of the status of all receivables. Collection losses have been within the Company’s expectations.
	Inventories
	Inventories are stated at the lower of cost or market using the first-in, first-out (“FIFO”) method for all entities excluding one of the Company’s subsidiaries, TB Wood’s. TB Wood’s inventory is stated at the lower of cost or market, principally using the last-in, first-out (“LIFO”) method. Inventory stated using the LIFO method approximates 7.0% and 7.5% of total inventory at December 31, 2014 and 2013, respectively.
	The cost of inventories acquired by the Company in its acquisitions reflect fair value at the date of acquisition as determined by the Company based on the replacement cost of raw materials, the sales price of the finished goods less an appropriate amount representing the expected profitability from selling efforts, and for work-in-process the sales price of the finished goods less an appropriate amount representing the expected profitability from selling efforts and costs to complete.
	The Company periodically reviews its quantities of inventories on hand and compares these amounts to the expected usage of each particular product or product line. The Company records a charge to cost of sales for any amounts required to reduce the carrying value of inventories to its estimated net realizable value.
	Property, Plant and Equipment
	Property, plant and equipment are stated at cost, net of accumulated depreciation.
	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
	Leasehold improvements are depreciated on a straight-line basis over the estimated life of the asset or the life of the lease, if shorter.
	Improvements and replacements are capitalized to the extent that they increase the useful economic life or increase the expected economic benefit of the underlying asset. Repairs and maintenance expenditures are charged to expense as incurred.
	Intangible Assets
	Intangible assets represent product technology, patents, tradenames, trademarks and customer relationships. Product technology, patents and customer relationships are amortized on a straight-line basis over 8 to 17 years, which approximates the period of economic benefit. The tradenames and trademarks are considered indefinite-lived assets and are not being amortized. Intangibles are stated at fair value on the date of acquisition. Intangibles are stated net of accumulated amortization.
	Goodwill
	Goodwill represents the excess of the purchase price paid by the Company over the fair value of the net assets acquired in each of the Company’s acquisitions.
	Impairment of Goodwill and Indefinite-Lived Intangible Assets
	The Company conducts an annual impairment review of goodwill and indefinite-lived intangible assets in December of each year, unless events occur which trigger the need for an interim impairment review.
	In connection with the Company’s annual impairment review, goodwill is assessed for impairment by comparing the fair value of the reporting unit to the carrying value using a two-step approach. In the first step, the Company estimates future cash flows based upon historical results and current market projections, discounted at a market comparable rate. If the carrying amount of the reporting unit exceeds the estimated fair value, impairment may be present, the Company would then be required to perform a second step in its impairment analysis. In the second step, the Company would evaluate impairment losses based upon the fair value of the underlying assets and liabilities of the reporting unit, including any unrecognized intangible assets, and estimate the implied fair value of the goodwill. An impairment loss is recognized to the extent that a reporting unit’s recorded value of the goodwill asset exceeded its deemed fair value. In addition, to the extent the implied fair value of any indefinite-lived intangible asset is less than the asset’s carrying value, an impairment loss is recognized on those assets. The Company did not identify any impairment of goodwill during the periods presented.
	For our indefinite-lived intangible assets, mainly trademarks, we estimated the fair value first by estimating the total revenue attributable to the trademarks for each of the reporting units. Second, we estimated an appropriate royalty rate using the return on assets method by estimating the required financial return on our assets, excluding trademarks, less the overall return generated by our total asset base. The return as a percentage of revenue provides an indication of our royalty rate (between 1.0% and 1.25%). We compared the estimated fair value of our trademarks with the carrying value of the trademarks and did not identify any impairment. The Company did not identify any impairment of indefinite-lived intangible assets during the periods presented.
	Preparation of forecasts of revenue and profitability growth for use in the long-range plan and the discount rate require significant use of judgment. Changes to the discount rate and the forecasted profitability could affect the estimated fair value of one or more of the Company’s reporting units and could result in a goodwill impairment charge in a future period.
	Impairment of Long-Lived Assets Other Than Goodwill and Indefinite-Lived Intangible Assets
	Long-lived assets, including definite-lived intangible assets, are reviewed for impairment when events or circumstances indicate that the carrying amount of a long-lived asset may not be recovered. Long-lived assets are considered to be impaired if the carrying amount of the asset exceeds the undiscounted future cash flows expected to be generated by the asset over its remaining useful life. If an asset is considered to be impaired, the impairment is measured by the amount by which the carrying amount of the asset exceeds its fair value, and is charged to results of operations at that time.
	The Company did not identify any impairment of long-lived assets in the periods presented.
	Determining fair values based on discounted cash flows requires management to make significant estimates and assumptions, including forecasting of revenue and profitability growth for use in the long-range plan and estimating appropriate discount rates. Changes to the discount rate and the forecasted profitability could affect the estimated fair value of one or more of the Company’s indefinite-lived intangible assets and could result in an impairment charge in a future period.
	Debt Issuance Costs
	Costs directly related to the issuance of debt are capitalized, included in other non-current assets and amortized using the effective interest method over the term of the related debt obligation. The net carrying value of debt issuance costs was approximately $3.2 million and $4.1 million at December 31, 2014 and 2013, respectively.
	Revenue Recognition
	Product revenues are recognized, net of sales tax collected, at the time title and risk of loss pass to the customer, which generally occurs upon shipment to the customer. Product return reserves are accrued at the time of sale based on the historical relationship between shipments and returns, and are recorded as a reduction of net sales.
Certain large distribution customers receive annual volume discounts, which are estimated at the time the sale is recorded based on the estimated annual sales.
Shipping and Handling Costs
Shipping and handling costs associated with sales are classified as a component of cost of sales. Amounts collected from our customers for shipping and handling are recognized as revenue.
Warranty Costs
Estimated expenses related to product warranties are accrued at the time products are sold to customers. Estimates are established using historical information as to the nature, frequency, and average costs of warranty claims. See Note 6 to the consolidated financial statements.
Self-Insurance
Certain exposures are self-insured up to pre-determined amounts, above which third-party insurance applies, for medical claims, workers’ compensation, vehicle insurance, product liability costs and general liability exposure. The accompanying balance sheets include reserves for the estimated costs associated with these self-insured risks, based on historic experience factors and management’s estimates for known and anticipated claims. A portion of medical insurance costs are offset by charging employees a premium equivalent to group insurance rates.
Research and Development
Research and development costs are expensed as incurred.
Advertising
Advertising costs are charged to selling, general and administrative expenses as incurred and amounted to approximately $2.9 million, $2.5 million and $2.1 million, for the years ended December 31, 2014, 2013, and 2012, respectively.
Stock-Based Compensation
The Company's 2004 Equity Incentive Plan (the “2004 Plan”) permitted the grant of various forms of stock based compensation to our officers and senior level employees.  The 2004 Plan expired in 2014 and, upon expiration, there were 750,576 shares subject to outstanding awards under the 2004 Plan.  The 2014 Omnibus Incentive Plan (the “2014 Plan”) was approved by the Company's shareholders at its 2014 annual meeting.  The 2014 Plan provides for various forms of stock based compensation to our directors, executive personnel and other key employees and consultants. Under the 2014 Plan, the total number of shares of common stock available for delivery pursuant to the grant of awards (“Awards”) was originally 750,000. Shares of our common stock subject to Awards or awarded under the 2004 Plan and outstanding as of the effective date of the 2014 Plan (except for substitute awards) that terminate without being exercised, expire, are forfeited or canceled, are exchanged for Awards that did not involve shares of common stock, are not issued on the stock settlement of a stock appreciation right, are withheld by the Company or tendered by a participant (either actually or by attestation) to pay an option exercise price or to pay the withholding tax on any Award, or are settled in cash in lieu of shares will again be available for Awards under the 2014 Plan. The Company recognizes stock based compensation expense on a straight line basis for shares vesting ratably under the 2004 Plan and 2014 Plan and uses the graded-vesting method of recognizing stock-based compensation expense for performance share awards based on the probability of the specific performance metrics being achieved over the requisite service period.
Income Taxes
The Company records income taxes using the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and operating loss and tax credit carryforwards. The Company evaluates the realizability of its net deferred tax assets and assesses the need for a valuation allowance on a quarterly basis. The future benefit to be derived from its deferred tax assets is dependent upon the Company’s ability to generate sufficient future taxable income to realize the assets. The Company records a valuation allowance to reduce its net deferred tax assets to the amount that may be more likely than not to be realized.
To the extent the Company establishes a valuation allowance on net deferred tax assets generated from operations, an expense will be recorded within the provision for income taxes. In periods subsequent to establishing a valuation allowance on net deferred assets from operations, if the Company were to determine that it would be able to realize its net deferred tax assets in excess of their net recorded amount, an adjustment to the valuation allowance would be recorded as a reduction to income tax expense in the period such determination was made.
We assess our income tax positions and record tax benefits for all years subject to examination, based upon our evaluation of the facts, circumstances and information available at the reporting date. For those tax positions for which it is more likely than not that a tax benefit will be sustained, we record the amount that has a greater than 50% likelihood of being realized upon settlement with the taxing authority that has full knowledge of all relevant information. Interest and penalties are related to unrecognized tax benefits in income tax expense in the consolidated statement of income and included in accruals and other long-term liabilities in the Company's consolidated balance sheet, where applicable. If we do not believe that it is more likely than not that a tax benefit will be sustained, no tax benefit is recognized.
Changes in Accumulated Other Comprehensive Loss by Component
The following is a reconciliation of changes in Accumulated Other Comprehensive Loss for the periods presented:
	Interest Rate Swap		Defined			Cumulative			Total
			Benefit			Foreign
			Pension Plans			Currency
						Translation
Accumulated Other Comprehensive Loss by Component, January 1, 2012	$	—	$	(2,485	)	$	(22,591	)	$	(25,076	)
Net current-period Other Comprehensive Income	—		(2,122		)	3,795			1,673
Accumulated Other Comprehensive Loss by Component, January 1, 2013	—		(4,607		)	(18,796		)	(23,403		)
Net current-period Other Comprehensive Income	135		1,474			3,398			5,007
Accumulated Other Comprehensive Income (Loss) by component, January 1, 2014	135		(3,133		)	(15,398		)	(18,396		)
Net current-period Other Comprehensive Income (Loss)	8		(1,685		)	(21,342		)	(23,019		)
Accumulated Other Comprehensive Income (Loss) by component, December 31, 2014	$	143	$	(4,818	)	$	(36,740	)	$	(41,415	)

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Acquisitions	Acquisitions
	Guardian Couplings
	On July 1, 2014, the Company acquired all of the issued and outstanding shares of Guardian Ind., Inc. (“Guardian Couplings”) for cash consideration of $17.1 million. This transaction is referred to as the Guardian Acquisition. Guardian Couplings is a manufacturer and supplier of flywheel, motion control and general industrial couplings. The Guardian Acquisition provides the Company with increased product coverage in several core markets, including energy, farm and agriculture, and specialty machinery and is expected to provide synergies with the Company's existing product offerings.
	The sellers agreed to provide the Company with a limited set of representations and warranties, including those with respect to outstanding and potential liabilities. Claims for a breach of a representation or warranty are secured by a limited escrow. There is no guarantee that the Company would actually be able to recover all or any portion of the sums payable in connection with such breach.
	The Company is in the process of finalizing the valuation of certain intangibles, the related tax impact and the valuation of certain tax information to finalize fair value. The Company believes that such preliminary allocations provide a reasonable basis for estimating the fair values of assets acquired and liabilities assumed. The purchase price of $17.1 million, excluding acquisition costs of $0.2 million, is in excess of the fair value of net assets acquired by approximately $2.2 million. Current assets acquired, excluding approximately $2.0 million in cash, totaled approximately $4.0 million, non-current assets totaled approximately $9.2 million and current liabilities totaled approximately $0.3 million.
	The excess of the purchase price over the fair value of the net assets acquired was recorded as goodwill. This goodwill is deductible for income tax purposes over a period of 15 years. The Company expects to develop synergies, such as lower cost country sourcing and global procurement.
	The non-current assets acquired included the following intangible assets:
	Customer relationships, subject to amortization	$	7,450
	Trade names and trademarks, not subject to amortization	650
	Total intangible assets	$	8,100
	Customer relationships are subject to amortization which will be amortized on a straight-line basis over their estimated useful lives of 14 years, which represents the anticipated period over which the Company estimates it will benefit from the acquired assets.
	Svendborg Brakes
	In December 2013, the Company consummated an agreement (the "Purchase Agreement") to acquire all of the issued and outstanding shares of Svendborg Brakes A/S and S.B. Patent Holding ApS (together “Svendborg”) for cash consideration of €80.1 million ($110.2 million), less the cash remaining on the balance sheet at close of €5.4 million ($7.5 million). This transaction is referred to as the Svendborg Acquisition. Through the Svendborg Acquisition, the Company acquired the leading global manufacturer of premium quality caliper brakes. With the Svendborg Acquisition, in addition to a presence in Denmark, the Company acquired Svendborg’s well-established sales network in 7 additional countries in Western Europe, China, South America, Australia and the United States as well as a manufacturing facility in China.
	Under the Purchase Agreement, the seller agreed to provide the Company with a limited set of representations and warranties, including with respect to outstanding and potential liabilities. Claims for a breach of a representation or warranty are secured by a limited escrow and warranty and indemnity insurance. Damages resulting from a breach of a representation or warranty could have a material and adverse effect on the Company’s financial condition and results of operations, and there is no guarantee that the Company would actually be able to recover all or any portion of the sums payable in connection with such breach.
	Under the Purchase Agreement, the seller agreed to provide the Company with an indemnification for certain tax liabilities related to transfer pricing (the “Transfer Pricing Claims”) identified as part of an ongoing tax audit in Denmark. As part of the Purchase Agreement, an escrow in the amount of approximately €8.5 million ($11.6 million) was established for the Transfer Pricing Claims. The Company estimated this liability to be $8.1 million and as a result initially recorded a liability included in taxes payable and an escrow receivable in other current assets. The purchase price in the reconciliation below represents cash consideration less the estimated escrow receivable for which the Company expects to be indemnified.
	During the year ended December 31, 2014, the Company paid approximately €5.9 million ($8.1 million) to settle a portion of the Transfer Pricing Claims and received a corresponding amount from the escrow established for the Transfer Pricing Claims.
	Measurement period adjustments reflect new information obtained about facts and circumstances that existed as of the acquisition date. The Company updated the acquisition accounting for the measurement period adjustments noted in the table below during the year ended December 31, 2014.
		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		(715		)	20,860
	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		(1,015		)	121,248
	Accounts payable	4,833		—			4,833
	Accrued expenses and other current liabilities	9,620		517			10,137
	Taxes payable	10,254		—			10,254
	Deferred tax liability	11,483		431			11,914
	Total liabilities assumed	36,190		948			37,138
	Net assets acquired	86,073		(1,963		)	84,110
	Excess of purchase price over fair value of net assets acquired	$	16,023	$	1,963		$	17,986
	The excess of the purchase price over the fair value of the net assets acquired was recorded as goodwill. This goodwill is not deductible for income tax purposes. The Company expects to develop synergies, such as lower cost country sourcing, global procurement, the ability to cross-sell product, and the ability to penetrate certain geographic areas, as a result of the acquisition of Svendborg.
	Customer relationships, subject to amortization	$	40,050
	Trade names and trademarks, not subject to amortization	8,500
	Patents	343
	Total intangible assets	$	48,893
	Customer relationships are subject to amortization which will be amortized on a straight-line basis over their estimated useful lives of 17 years, which represents the anticipated period over which the Company estimates benefits from the acquired assets will be realized.
	The following table sets forth the unaudited pro forma results of operations of the Company for the year to date periods ended December 31, 2014, 2013 and 2012 as if the Company had acquired Svendborg at January 1, 2012, and Guardian at January 1, 2013. The pro forma information contains the actual operating results of the Company, including Svendborg and Guardian, adjusted to include the pro forma impact of (i) additional depreciation expense as a result of estimated depreciation based on the fair value of fixed assets and; (ii) additional expense as a result of the estimated amortization of identifiable intangible assets; (iii) elimination of certain acquisition related expenses (iv) reduction in costs of goods sold related to the amortization of inventory fair value adjustment (v) additional interest expense for borrowings under the Credit Agreement associated with the Svendborg and Guardian Acquisitions. 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.
		2014		2013			2012
	Total revenues	$	825,723	$	813,477		$	818,956
	Net income attributable to Altra Industrial Motion Corp.	$	42,632	$	38,695		$	22,373
	Basic earnings per share:
	Net income attributable to Altra Industrial Motion Corp.	$	1.6	$	1.45		$	0.84
	Diluted earnings per share:
	Net income attributable to Altra Industrial Motion Corp.	$	1.56	$	1.44		$	0.84

Inventories

Inventories	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventories	Inventories
	Inventories consisted of the following:
		December 31,		December 31,
		2014		2013
	Raw materials	$	36,814	$	56,824
	Work in process	13,641		18,432
	Finished goods	82,281		68,409
	Inventories, net	$	132,736	$	143,665
	Approximately 7.0% of total inventories at December 31, 2014, were valued using the LIFO method. The Company recorded as a component of cost of sales, a $0.1 million, and a $0.7 million provision in the years ended December 31, 2014 and 2013, respectively. If the LIFO inventory was accounted for using the FIFO method, the inventory balance at December 31, 2014 and 2013, would be $1.7 million higher and $1.6 million higher, respectively.

Property_Plant_and_Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment
	Property, plant and equipment consisted of the following:
		2014			2013
	Land	$	26,560		$	20,803
	Buildings and improvements	44,791			53,078
	Machinery and equipment	220,896			207,193
		292,247			281,074
	Less-Accumulated depreciation	(135,881		)	(123,539		)
		$	156,366		$	157,535
	The Company recorded $23.1 million, $21.4 million and $20.5 million of depreciation expense in the years ended December 31, 2014, 2013, and 2012, respectively.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets
	The changes in the carrying value of goodwill by segment for the years ended December 31, 2014 and 2013 are as follows:
		Clutches and Brakes			Couplings			Gearing & Power Transmission Components			Total
	Gross goodwill balance as of January 1, 2013	$	37,784		$	36,138		$	46,113		$	120,035
	Accumulated Impairment January 1, 2013	(3,745		)	(14,982		)	(13,083		)	(31,810		)
	Purchase price accounting adjustments	16,023			—			—			16,023
	Impact of changes in foreign currency and other	418			(414		)	87			91
	Net goodwill balance December 31, 2013	50,480			20,742			33,117			104,339
	Purchase price accounting adjustments	1,963			2,180			—			4,143
	Impact of changes in foreign currency and other	(4,741		)	(512		)	(1,142		)	(6,395		)
	Net goodwill balance December 31, 2014	$	47,702		$	22,410		$	31,975		$	102,087
	Purchase accounting adjustments in the Clutches and Brakes segment and Couplings segment relate to the Svendborg Acquisition and Guardian Acquisition, respectively.
	The following table provides the gross carrying value and accumulated amortization for each major class of intangible asset:
		December 31, 2014												December 31, 2013
		Cost				Accumulated				Net				Cost		Accumulated		Net
						Amortization										Amortization
	Intangible Assets
	Intangible assets not subject to amortization:
	Tradenames and trademarks	$	41,257			$	—			$	41,257			$	42,605	$	—	$	42,605
	Intangible assets subject to amortization:
	Customer relationships	118,523				49,849				68,674				117,848		42,582		75,266
	Product technology and patents	6,830				6,031				799				6,983		6,086		897
	Total intangible assets	$	166,610			$	55,880			$	110,730			$	167,436	$	48,668	$	118,768
	The Company recorded $9.0 million, $6.5 million, and $6.8 million of amortization for the years ended December 31, 2014, 2013 and 2012, respectively.
	Customer relationships, product technology and patents are amortized over their useful lives ranging from 8 to 17 years. The weighted average estimated useful life of intangible assets subject to amortization is approximately 11 years.
	The estimated amortization expense for intangible assets is approximately $8.2 million in 2015, $8.2 million in each of the next four years and then $28.5 million thereafter.

Warranty_Costs

Warranty Costs	12 Months Ended
	Dec. 31, 2014
Guarantees [Abstract]
Warranty Costs	Warranty Costs
	The contractual warranty period of the Company's products generally ranges from three months to two years with certain warranties extending for longer periods. Estimated expenses related to product warranties are accrued at the time products are sold to customers and are recorded in accruals and other current liabilities on the consolidated balance sheet. Estimates are established using historical information as to the nature, frequency and average costs of warranty claims. Changes in the carrying amount of accrued product warranty costs for each of the years ended December 31, are as follows:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Balance at beginning of period	$	8,739		$	5,625		$	4,898
	Accrued current period warranty costs	1,537			2,573			2,386
	Acquired warranty reserves	—			3,420			—
	Payments and adjustments	(2,484		)	(2,879		)	(1,659		)
	Balance at end of period	$	7,792		$	8,739		$	5,625

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	Income before income taxes by domestic and foreign locations consists of the following:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Domestic	$	33,065		$	37,640		$	18,083
	Foreign	30,053			21,696			16,276
	Total	$	63,118		$	59,336		$	34,359
	The components of the provision for income taxes consist of the following:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Current:
	Federal	$	12,545		$	8,917		$	8,370
	State	299			698			(3,597		)
	Non-US	7,380			6,072			6,006
		20,224			15,687			10,779
	Deferred:
	Federal	2,673			3,533			(915		)
	State	198			378			1,756
	Non-US	(159		)	(447		)	(1,466		)
		2,712			3,464			(625		)
	Provision for income taxes	$	22,936		$	19,151		$	10,154
	A reconciliation from tax at the U.S. federal statutory rate to the Company’s provision for income taxes is as follows:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Tax at US federal income tax rate	$	22,092		$	20,767		$	12,026
	State taxes, net of federal income tax effect	495			905			67
	Change in tax rate	11			(354		)	(267		)
	Foreign reorganization	3,786			—			—
	Foreign taxes	(1,978		)	(224		)	781
	Adjustments to accrued income tax liabilities and uncertain tax positions	(287		)	(52		)	(1,289		)
	Valuation allowance	612			120			506
	Intercompany interest	(910		)	(986		)	(1,676		)
	Tax credits and incentives	(666		)	(816		)	(291		)
	Domestic manufacturing deduction	(1,201		)	(839		)	(566		)
	Other	982			630			863
	Provision for income taxes	$	22,936		$	19,151		$	10,154
	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 states. The Company and its subsidiaries also file consolidated and separate income tax returns in various non-U.S. 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 2011. Additionally, the Company has indemnification agreements with the sellers of the Guardian, Svendborg, Lamiflex and Bauer entities that provide for reimbursement to the Company for payments made in satisfaction of income tax liabilities relating to pre-acquisition periods.
	A reconciliation of the gross amount of unrecognized tax benefits excluding accrued interest and penalties is as follows:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Balance at beginning of period	$	627		$	747		$	3,523
	Increases related to prior year tax positions	—			—			—
	Decreases related to prior year tax positions	—			(33		)	—
	Increases related to current year tax positions	—			—			—
	Settlements	(176		)	—			(2,689		)
	Lapse of statute of limitations	(17		)	(87		)	(87		)
	Balance at end of period	$	434		$	627		$	747
	In 2012, the Company recognized a $2.5 million tax benefit for the reduction of the Company’s reserve for uncertain tax positions due to a settlement with the State of New York for which the Company was fully indemnified.
	The Company recognizes interest and penalties related to unrecognized tax benefits in income tax expense in the Consolidated Statement of Income. The Company accrued interest and penalties of $0.1 million (off-set by a $0.3 million benefit of interest and penalties primarily related to the lapse of the applicable statute of limitations), $0.1 million, and $0.2 million during the years ended December 31, 2014, 2013 and 2012, respectively. The total gross amount of interest and penalties related to uncertain tax positions at December 31, 2014, 2013, and 2012 was $0.2 million, $0.4 million, $0.4 million, respectively. Although it is reasonably possible that a change in the balance of unrecognized tax benefits might occur within the next twelve months, at this time it is not possible to estimate the range of change due to the uncertainty of the potential outcomes.
	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.
	Significant components of the deferred tax assets and liabilities as of December 31, 2014 and 2013 are as follows:
		2014			2013
	Deferred tax assets:
	Post-retirement obligations	$	1,363		$	1,565
	Tax credits	2,194			2,165
	Expenses not currently deductible	11,457			11,788
	Net operating loss carryover	5,901			6,376
	Other	519			546
	Total deferred tax assets	21,434			22,440
	Valuation allowance for deferred tax assets	(5,974		)	(5,577		)
	Net deferred tax assets	15,460			16,863
	Deferred tax liabilities:
	Property, plant and equipment	19,002			20,065
	Intangible assets	22,735			25,090
Basis difference - convertible debt	11,875			11,064
Goodwill	4,967			3,813
Total deferred liabilities	58,579			60,032
Net deferred tax liabilities	$	43,119		$	43,169
On December 31, 2014 the Company had state net operating loss (NOL) carry forwards of $24.3 million, which expire between 2019 and 2032, and non U.S. NOL and capital loss carryforwards of $21.8 million, of which substantially all have an unlimited carryforward period. The NOL carryforwards available are subject to limitations on their annual usage. The Company also has federal and state tax credits of $2.4 million available to reduce future income taxes that expire between 2015 and 2029.
Valuation allowances are established for deferred tax assets when management believes it is more likely than not that the associated benefit may not be realized. The Company periodically reviews the adequacy of its valuation allowances and recognizes tax benefits only as reassessments indicate that it is more likely than not the benefits will be realized. Valuation allowances have been established due to the uncertainty of realizing the benefits of certain net operating losses, capital loss carryforwards, tax credits, and other tax attributes. The valuation allowances are primarily related to certain non-U.S. NOL carryforwards, capital loss carryforwards, and U.S. federal foreign tax credits.
A provision has not been made for U.S. or additional non-U.S. taxes on $70.8 million of undistributed earnings of international subsidiaries that could be subject to taxation if remitted to the U.S. because the Company plans to keep these amounts permanently reinvested outside the U.S. except for instances where the Company has already been subject to tax in the U.S. It is not practicable to determine the amount of deferred income taxes not provided on these earnings.

Pension_and_Other_Employee_Ben

Pension and Other Employee Benefits	12 Months Ended
	Dec. 31, 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 benefit obligation, fair value of plan assets and funded status of the respective defined benefit (pension) plans as of December 31, 2014 and 2013:
		Pension Benefits
		Year Ended				Year Ended
		December 31,				December 31,
		2014				2013
	Change in benefit obligation:
	Obligation at beginning of period	$	32,215			$	34,629
	Partial settlement gain	(582		)		—
	Service cost	243				248
	Interest cost	1,353				1,250
	Partial settlement payments	(2,080		)		—
	Actuarial (gains) losses	5,978				(2,969		)
	Foreign exchange effect	(909		)		343
	Benefits paid	(1,357		)		(1,286		)
	Obligation at end of period	$	34,861			$	32,215
	Change in plan assets:
	Fair value of plan assets, beginning of period	$	24,190			$	20,100
	Partial settlement payments	(2,080		)		—
	Actual return on plan assets	3,668				182
	Employer contributions	447				5,194
	Benefits paid	(1,357		)		(1,286		)
	Fair value of plan assets, end of period	$	24,868			$	24,190
	Funded status	$	(9,993	)		$	(8,025	)
	Amounts Recognized in the balance sheet consist of:
	Non-current liabilities	$	(9,993	)		$	(8,025	)
	Total	$	(9,993	)		$	(8,025	)
	For all pension plans presented above, the accumulated and projected benefit obligations exceed the fair value of plan assets. The accumulated benefit obligation at December 31, 2014 and 2013 was $34.9 million and $32.2 million, respectively. Non-U.S. pension liabilities recognized in the amounts presented above are $8.3 million and $7.7 million at December 31, 2014 and 2013, respectively.
	Included in accumulated other comprehensive loss at December 31, 2014 and 2013, is $4.8 million (net of $1.7 million in taxes) and $3.1 million (net of $1.1 million in taxes), respectively, of unrecognized actuarial losses that have not yet been recognized in net periodic pension cost.
	The discount rate used in the computation of the respective benefit obligations at December 31, 2014 and 2013, presented above are as follows:
		2014			2013
	Pension benefits	3.7	%		4.6	%
	The following table represents the components of the net periodic benefit cost associated with the respective plans:
		Pension Benefits
		Year Ended				Year Ended				Year Ended
		December 31,				December 31,				December 31,
		2014				2013				2012
	Service cost	$	243			$	248			$	179
	Interest cost	1,353				1,250				1,381
	Expected return on plan assets	(1,084		)		(1,080		)		(1,083		)
	Non-cash impact of partial pension settlement	475				—				—
	Amortization of actuarial losses	159				175				105
	Net periodic benefit cost	$	1,146			$	593			$	582
	The key economic assumptions used in the computation of the respective net periodic benefit cost for the periods presented above are as follows:
		Pension Benefits
		Year Ended			Year Ended			Year Ended
		December 31,			December 31,			December 31,
		2014			2013			2012
	Discount rate	4.6	%		3.75	%		4.75	%
	Expected return on plan assets	4.6	%		5.25	%		6.25	%
	The expected long-term rate of return represents the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation. The assumption reflects expectations regarding future rates of return for the investment portfolio, with consideration given to the distribution of investments by asset class and historical rates of return for each individual asset class.
	Fair Value of Plan Assets
	The fair value of the Company’s pension plan assets at December 31, 2014 and 2013 by asset category is as follows:
		2014				2013
	Asset Category
	Fixed income (Level 1)
	U.S. government	3,554				2,787
	Corporate bonds
	Investment grade	17,682				17,091
	High yield	3,090				3,634
	Total fixed income	24,326				23,512
	Other (Level 2)	286				338
Cash and cash equivalents (Level 1)	256				340
Total assets at fair value	$	24,868			$	24,190
The asset allocations for the Company’s funded retirement plan at December 31, 2014 and 2013, respectively, and the target allocation for 2014, by asset category, are as follows:
	Allocation Percentage of
	Plan Assets at Year-End
	2014			2014		2013
	Actual			Target		Actual
Asset Category
Investment Grade Bonds	86	%		70% - 100%		84	%
High Yield Bonds	13	%		0% - 25%		15	%
Cash	1	%		0% - 5%		1	%
The investment strategy is to achieve a rate of return on the plan’s assets that meets the performance of liabilities as calculated using a bank’s liability index with appropriate adjustments for benefit payments, service cost and actuarial assumption changes. A determinant of the plan’s return is the asset allocation policy. The plan’s asset mix will be reviewed by the Company periodically, but at least quarterly, to rebalance within the target guidelines. The Company will also periodically review investment managers to determine if the respective manager has performed satisfactorily when compared to the defined objectives, similarly invested portfolios, and specific market indices.
Expected cash flows
The following table provides the amounts of expected benefit payments, which are made from the plans’ assets and includes the participants’ share of the costs, which is funded by participant contributions. The amounts in the table are actuarially determined and reflect the Company’s best estimate given its current knowledge; actual amounts could be materially different.
	Pension
	Benefits
Expected benefit payments (from plan assets)
2015	1,287
2016	1,366
2017	1,409
2018	1,488
2019	1,564
Thereafter	7,858
The Company contributed $0.2 million to its U.S. pension plan in 2014. The Company has no minimum cash funding requirements associated with its pension plans for years 2015 through 2019.
Defined Contribution Plans
Under the terms of the Company’s defined contribution plans, eligible employees may contribute up to 75% percent of their compensation to the plan on a pre-tax basis, subject to annual IRS limitations. The Company makes matching contributions equal to half of the first six percent of salary contributed by each employee and made a unilateral contribution (including for non-contributing employees). The Company’s expense associated with the defined contribution plans was $4.0 million, $3.7 million and $3.5 million during the years ended December 31, 2014 , 2013 and 2012, respectively.

LongTerm_Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt
		December 31,				December 31,
		2014				2013
	Debt:
	Revolving Credit Facility	$	40,000			$	41,198
	Convertible Notes	85,000				85,000
	Term Loan Facility	133,697				163,245
	Bauer Mortgage	3,647				—
	Equipment Loan	5,430				4,155
	Mortgages	258				659
	Capital leases	476				178
	Total debt	268,508				294,435
	Less: debt discount, net of accretion	(12,756		)		(16,163		)
	Total debt, net of unaccreted discount	255,752				278,272
	Less current portion of long-term debt	(15,176		)		(16,924		)
	Total long-term debt	$	240,576			$	261,348
	Credit Agreement
	In December 2013, the Company entered into an Amended and Restated Credit Agreement (the “Credit Agreement”). The Credit Agreement amends and restates the Company’s former credit agreement, dated November 20, 2012. Pursuant to the former credit agreement, the former lenders made available to the Company an initial term loan facility of $100,000,000 and an initial revolving credit facility of $200,000,000.
	Pursuant to the Credit Agreement, the lenders made an additional term loan of €50,000,000 (the “Additional Term Loan”) to Altra Industrial Motion Netherlands B.V. The Credit Agreement kept in effect the balance (approximately $94,375,000) of the existing term loan facility (the “Initial Term Loan”) made to the domestic borrowers under the former credit agreement (collectively, the two term loans are referred to as the “Term Loan Facility”), as well as the revolving credit facility of $200,000,000 made under the Former Credit Agreement (the “Revolving Credit Facility”). The Credit Agreement continues, even after the making of the Additional Term Loan, to provide for a possible expansion of the credit facilities by an additional $150,000,000, which can be allocated as additional term loans and/or additional revolving credit loans. The amounts available under the Term Loan Facility were used, and amounts available under the Revolving Credit Facility can be used, for general corporate purposes, including acquisitions, and to repay existing indebtedness. The stated maturity of these credit facilities is December 6, 2018, and there are scheduled quarterly principal payments due on the outstanding amount of the Term Loan Facility. With respect to the Initial Term Loan, the scheduled quarterly principal payments due on the outstanding amount have been reset to amortize in accordance with the new December 6, 2018 maturity date. The previous maturity of the Revolving Credit Facility and the Initial Term Loan was November 20, 2017.
	The amounts available under the Revolving Credit Facility may be drawn upon in accordance with the terms of the Credit Agreement. All amounts outstanding under the credit facilities are due on the stated maturity or such earlier time, if any, required under the Credit Agreement. The amounts owed under either of the credit facilities may be prepaid at any time, subject to usual notification and breakage payment provisions. Interest on the amounts outstanding under the credit facilities is calculated using either an ABR Rate or Eurodollar Rate, plus the applicable margin. The applicable margins for Eurodollar Loans are between 1.375% to 1.875%, and for ABR Loans are between 0.375% and 0.875%. The amounts of the margins are calculated based on either a consolidated total net leverage ratio (as defined in the Credit Agreement), or the then applicable rating(s) of the Company’s debt if and then to the extent as provided in the Credit Agreement. A portion of the Revolving Credit
	Facility may also be used for the issuance of letters of credit, and a portion of the amount of the Revolving Credit Facility is available for borrowings in certain agreed upon foreign currencies.
	As of December 31, 2014 and 2013, we had $40.0 million and $41.2 million outstanding on our Revolving Credit Facility, respectively. As of December 31, 2014 and 2013, we had $11.0 and $9.8 million in letters of credit outstanding, respectively. We had $149.0 million available under the Revolving Credit Facility at December 31, 2014.
	The Credit Agreement contains various affirmative and negative covenants and restrictions, which among other things, will require the Company and certain subsidiaries to provide certain financial reports to the Lenders, require the Company to maintain certain financial covenants relating to consolidated leverage and interest coverage, limit maximum annual capital expenditures, and limit the ability of the Company and its subsidiaries to incur or guarantee additional indebtedness, pay dividends or make other equity distributions, purchase or redeem capital stock or debt stock or debt, make certain investments, sell assets, engage in certain transactions, and effect a consolidation or merger. The Credit Agreement also contains customary events of default.
	Pledge and Security Agreement; Trademark Security Agreement; Patent Security Agreement.
	Pursuant to an Omnibus Reaffirmation and Ratification of Collateral Documents entered into on December 6, 2013 in connection with the Credit Agreement by and among the Company, the Loan Parties and the Administrative Agent (the “Ratification Agreement”), the Loan Parties (exclusive of the foreign subsidiary Borrower) have reaffirmed their obligations to the Lenders under the Pledge and Security Agreement. The Credit Agreement provides that the obligation to grant the security interest can cease upon the obtaining of certain corporate family credit ratings for the Company, but the obligation to grant a security interest is subject to subsequent reinstatement if the ratings are not maintained as provided in the Credit Agreement.
	Pursuant to the Ratification Agreement, the Loan Parties (other than the foregoing subsidiary Borrower) have also reaffirmed their obligations under each of the Patent Security Agreement and a Trademark Security Agreement.
	Pursuant to the Former Credit Agreement, on November 20, 2012, the Loan Parties and the Administrative Agent entered into a Pledge and Security Agreement (the “Pledge and Security Agreement”), pursuant to which each Loan Party pledges, assigns and grants to the Administrative Agent, on behalf of and for the ratable benefit of the Lenders, a security interest in all of its right, title and interest in, to and under all personal property, whether now owned by or owing to, or after acquired by or arising in favor of such Loan Party (including under any trade name or derivations), and whether owned or consigned by or to, or leased from or to, such Loan Party, and regardless of where located, except for specific excluded personal property identified in the Pledge and Security Agreement (collectively, the “Collateral”). Notwithstanding the foregoing, the Collateral does not include, among other items, more than 65% of the capital stock of the first tier foreign subsidiaries of the Company. The Pledge and Security Agreement contains other customary representations, warranties and covenants of the parties. The Credit Agreement provides that the obligation to grant the security interest can cease upon the obtaining of certain corporate family ratings for the Company, but the obligation to grant a security interest is subject to subsequent reinstatement if the ratings are not maintained as provided in the Credit Agreement.
	In connection with the Pledge and Security Agreement, certain of the Loan Parties delivered a Patent Security Agreement and a Trademark Security Agreement in favor of the Administrative Agent pursuant to which each of the Loan Parties signatory thereto pledges, assigns and grants to the Administrative Agent, on behalf of and for the ratable benefit of the Lenders, a security interest in all of its right, title and interest in, to and under all registered patents, patent applications, registered trademarks and trademark applications owned by such Loan Parties.
	Convertible Senior Notes
	In March 2011, the Company issued Convertible Senior Notes (the “Convertible Notes”) due March 1, 2031. The Convertible Notes are guaranteed by the Company’s U.S. domestic subsidiaries. Interest on the Convertible Notes is payable semi-annually in arrears, on March 1 and September 1 of each year, commencing on September 1, 2011 at an annual rate of 2.75%. Proceeds from the offering were $81.3 million, net of fees and expenses that were capitalized. The proceeds from the offering were used to fund the Bauer Acquisition, as well as bolster the Company’s cash position.
	The Convertible Notes will mature on March 1, 2031, unless earlier redeemed, repurchased by the Company or converted, and are convertible into cash or shares, or a combination thereof, at the Company’s election. The Convertible Notes are convertible into shares of the Company’s common stock based on an initial conversion rate, subject to adjustment, of 36.0985 shares per $1,000 principal amount of notes (which represents an initial conversion price of approximately $27.70 per share of our common stock), in certain circumstances. The conversion price at December 31, 2014 is $26.71 per share. Prior to March 1, 2030, the Convertible Notes are convertible only in the following circumstances: (1) during any fiscal quarter commencing after June 30, 2011 if the last reported sale price of the Company’s common stock is greater than or equal to 130% of the applicable conversion price for at least 20 trading days in the period of 30 consecutive trading days ending on the last trading day of the preceding fiscal quarter; (2) during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of notes for each trading day in the measurement period was less than 97% of the product of the last reported sale price of the Company’s common stock and the conversion rate on such trading day; (3) if the Convertible Notes have been called for redemption; or (4) upon the occurrence of specified corporate transactions. On or after March 1, 2030, and ending at the close of business on the second business day immediately preceding the maturity date, holders may convert their Convertible Notes at any time, regardless of the foregoing circumstances. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of common stock, or a combination thereof, at the Company’s election. The Company intends to settle the principal amount in cash and any additional amounts in shares of stock.
	If a fundamental change occurs, the Convertible Notes are redeemable at a price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest (including contingent interest and additional interest, if any) to, but excluding, the repurchase date. The Convertible Notes are also redeemable on each of March 1, 2018, March 1, 2021, and March 1, 2026 for cash at a price equal to 100% of the principal amount of the notes to be repurchased, plus accrued and unpaid interest (including contingent interest and additional interest, if any) to, but excluding, the option repurchase date.
	On or after March 1, 2015, the Company may call all or part of the Convertible Notes at a redemption price equal to 100% of the principal amount of the Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date, plus a “make-whole premium” payment in cash, shares of the Company’s common stock, or combination thereof, at the Company’s option, equal to the sum of the present values of the remaining scheduled payments of interest on the Convertible Notes to be redeemed through March 1, 2018 to, but excluding, the redemption date, if the last reported sale price of the Company’s common stock for 20 or more trading days in a period of 30 consecutive trading days ending on the trading day prior to the date the Company provides notice of redemption exceeds 130% of the conversion price in effect on each such trading day. On or after March 1, 2018, the Company may redeem for cash all or a portion of the notes at a redemption price of 100% of the principal amount of the Convertible Notes to be redeemed, plus accrued and unpaid interest (including contingent and additional interest, if any) to, but not including, the redemption date.
	The Company separately accounted for the debt and equity components of the Convertible Notes to reflect the issuer’s non-convertible debt borrowing rate, which interest costs are to be recognized in subsequent periods. The note payable principal balance at the date of issuance of $85.0 million was bifurcated into a debt component of $60.5 million and an equity component of $24.5 million. The difference between the note payable principal balance and the value of the debt component is being accreted to interest expense over the term of the notes. The debt component was recognized at the present value of associated cash flows discounted using a 8.25% discount rate, the borrowing rate at the date of issuance for a similar debt instrument without a conversion feature. The Company paid approximately $3.7 million of issuance costs associated with the Convertible Notes. The Company recorded $1.0 million of debt issuance costs as an offset to additional paid-in capital. The balance of $2.7 million of debt issuance costs is classified as other non-current assets and will be amortized over the term of the notes using the effective interest method.
	Because the last reported sale price of the Company's common stock did not exceed 130% of the current conversion price, which was $26.71, for at least 20 of the last 30 consecutive trading days in the fiscal quarter ended December 31, 2014, the Convertible Notes are not convertible at the election of the holders of the Convertible Notes at any time during the fiscal quarter ending March 31, 2015. The future convertibility will be monitored at each quarterly reporting date and will be analyzed dependent upon market prices of the Company's common stock during the prescribed measurement periods. Should the Convertible Notes become converted in future periods, the Company has the ability and intent to fund any potential payments of the principal amount of the debt with additional borrowings under the Revolving Credit Agreement.
	The carrying amount of the principal amount of the liability component, the unamortized discount, and the net carrying amount are as follows as of December 31, 2014:
		December 31,
		2014
	Principal amount of debt	$	85,000
	Unamortized discount	12,756
	Carrying value of debt	$	72,244
	Interest expense associated with the Convertible Notes consisted of the following :
		December 31,			December 31,			December 31,
		2014			2013			2012
	Contractual coupon rate of interest	$	2,338		$	2,338		$	2,338
	Accretion of Convertible Notes discount and amortization of deferred financing costs	3,760			3,494			3,239
	Interest expense for the Convertible Notes	$	6,098		$	5,832		$	5,577
	The effective interest yield of the Convertible Notes due in 2031 is 8.5% at December 31, 2014 and the cash coupon interest rate is 2.75%.
	Equipment and Working Capital Notes
	The Company entered into a loan with a bank to equip its new facility in Changzhou, China during 2013. The loan is secured by certain letters of credit issued by the Company’s U.S. bank in favor of the lending bank in China. As of December 31, 2013, the total available to borrow was 38.5 million RMB ($6.3 million). The note is due in installments from 2014 through 2016, with interest varying between 5.40% and 8.00%. The Company has a 33.3 million RMB ($5.4 million) line of credit outstanding at December 31, 2014. The note is callable by the bank at its discretion and as such, has been included in the current portion of long-term debt in the balance sheet at December 31, 2014 and 2013.
	Mortgage
	The Company has a mortgage with a bank secured by its facility in Heidelberg, Germany with an interest rate of 5.75% and is payable in monthly installments through September 2015. As of December 31, 2014 and 2013, the mortgage had a remaining principal balance of €0.2 million or $0.3 million, and €0.5 million or $0.7 million, respectively.
	Bauer Mortgage
	The Company entered an agreement with a bank for €6.0 million or $7.9 million for the construction of a new facility in Esslingen, Germany with an interest rate of 2.5% per year which is payable in monthly interest payments . The Company received €3.0 million or $3.6 million during 2014. The Company expects to receive the remainder of proceeds of this loan during the quarter ended March 31, 2015. The principal portion of the mortgage will be due in a lump-sum payment in May 2019.
	Capital Leases
	The Company leases certain equipment under capital lease arrangements, whose obligations are included in both short-term and long-term debt. Capital lease obligations amounted to approximately $0.5 million and $0.2 million at December 31, 2014 and 2013, respectively. Assets subject to capital leases are included in property, plant and equipment with the related amortization recorded as depreciation expense.
	Overdraft Agreements
	Certain of our foreign subsidiaries maintain overdraft agreements with financial institutions. There were no borrowings as of December 31, 2014 or 2013 under any of the overdraft agreements.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity
	Common Stock (amounts not in thousands)
	As of December 31, 2014, there were 90,000,000 shares of common stock authorized and 26,353,755 outstanding.
	Preferred Stock
	On December 20, 2006, the Company amended and restated its certificate of incorporation authorizing 10,000,000 shares of undesignated Preferred Stock (“Preferred Stock”). The Preferred Stock may be issued from time to time in one or more classes or series, the shares of each class or series to have such designations and powers, preferences, and rights, and qualifications, limitations and restrictions as determined by the Company’s Board of Directors. There was no Preferred Stock issued or outstanding at December 31, 2014 or 2013.
	Restricted Common Stock
	The Company's 2004 Equity Incentive Plan (the “2004 Plan”) permitted the grant of various forms of stock based compensation to our officers and senior level employees.  The 2004 Plan expired in 2014 and, upon expiration, there were 750,576 shares subject to outstanding awards under the 2004 Plan.  The 2014 Omnibus Incentive Plan (the “2014 Plan”) was approved by the Company's shareholders at its 2014 annual meeting.  The 2014 Plan provides for various forms of stock based compensation to our directors, executive personnel and other key employees and consultants. Under the 2014 Plan, the total number of shares of common stock available for delivery pursuant to the grant of awards (“Awards”) was originally 750,000. Shares of our common stock subject to Awards awarded under the 2004 Plan and outstanding as of the effective date of the 2014 Plan (except for substitute awards) that terminate without being exercised, expire, are forfeited or canceled, are exchanged for Awards that did not involve shares of common stock, are not issued on the stock settlement of a stock appreciation right, are withheld by the Company or tendered by a participant (either actually or by attestation) to pay an option exercise price or to pay the withholding tax on any Award, or are settled in cash in lieu of shares will again be available for Awards under the 2014 Plan.
	The restricted shares issued pursuant to the 2014 Plan generally vest ratably over a period ranging from immediately to five years from the date of grant, provided, that the vesting of the restricted shares may accelerate upon the occurrence of events. Common stock awarded under the 2014 Plan is generally subject to restrictions on transfer, repurchase rights, and other limitations and rights as set forth in the applicable award agreements. The shares are valued based on the share price on the date of grant.
	The 2014 Plan permits the Company to grant, among other things, restricted stock, restricted stock units, and performance share awards to key employees and other persons who make significant contributions to the success of the Company. The restrictions and vesting schedule for restricted stock granted under the 2014 Plan are determined by the Personnel and Compensation Committee of the Board of Directors. Compensation expense recorded (in selling, general and administrative expense) during the years ended December 31, 2014, 2013 and 2012 was $3.4 million ($2.9 million, net of tax), $3.2 million ($2.9 million, net of tax), and $2.7 million ($1.8 million, net of tax), respectively. The Company recognizes stock-based compensation expense on a straight-line basis for the shares vesting ratably under the plan and uses the graded-vesting method of recognizing stock-based compensation expense for the performance share awards based on the probability of the specific performance metrics being achieved over the requisite service period.
	The following table sets forth the activity of the Company’s restricted stock grants to date:
	Amounts not in thousands	Shares		Weighted-
				Average Grant
				Date Fair Value
	Restricted shares unvested January 1, 2014	149,635		$	23.02
	Shares granted	136,340		$	33.52
	Shares for which restrictions lapsed	(126,797	)	$	29.58
	Restricted shares unvested December 31, 2014	159,178		$	28.53
	Total remaining unrecognized compensation cost is approximately $3.7 million as of December 31, 2014, and will be recognized over a weighted average remaining period of two years. Based on the stock price at December 31, 2014, of $28.39 per share, the intrinsic value of these awards as of December 31, 2014, was $4.5 million. The fair market value of the shares in which the restrictions have lapsed was $3.8 million, $2.4 million, and $3.2 million, during 2014, 2013, and 2012, respectively. Restricted shares granted are valued based on the fair market value of the stock on the date of grant.
	Share Repurchase Program
	In May 2014, our board of directors approved a new share repurchase program authorizing the buyback of up to $50.0 million of the Company's common stock. The Company expects to purchase shares on the open market, through block trades, in privately negotiated transactions, in compliance with SEC Rule 10b-18 (including through Rule 10b5-1 plans), or in any other appropriate manner. The timing of the shares repurchased will be at the discretion of management and will depend on a number of factors, including price, market conditions and regulatory requirements. Shares acquired through the repurchase program will be retired. The Company retains the right to limit, terminate or extend the share repurchase program at any time without prior notice.
	For the year ended December 31, 2014, the Company repurchased 545,154 shares of common stock at an average purchase price of $32.32 per share.   As of December 31, 2014, up to $32.3 million was available for repurchase under the repurchase program, which expires on December 31, 2016. The Company expects to fund any further repurchases of its common stock through a combination of cash on hand, cash generated by operations.
	Dividends
	The Company declared and paid dividends of $0.46 per share of common stock for the year ended December 31, 2014. The Company declared dividends of $0.38 per share for the year ended December 31, 2013, of which $0.10 or $2.7 million was paid on January 3, 2014 and accrued for in the balance sheet at December 31, 2013.
	Future declarations of quarterly cash dividends are subject to approval by the Board of Directors and to the Board’s continuing determination that the declaration of dividends are in the best interest of the Company’s stockholders and are in compliance with all laws and agreements of the Company applicable to the declaration and payment of cash dividends.

Concentrations

Concentrations	12 Months Ended
	Dec. 31, 2014
Risks and Uncertainties [Abstract]
Concentrations	Concentrations
	Financial instruments, which are potentially subject to counterparty 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 the years ended December 31, 2014, 2013 and 2012.
	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 investments are held by well-established financial institutions and invested in AAA rated mutual funds or United States Government Securities. The Company is exposed to swap counterparty credit risk with financial institutions. The Company’s counterparty is a well-established financial institution.
	Approximately 23% of the Company’s labor force (15% and 56% in the United States and Europe, respectively) is represented by collective bargaining agreements. The Company is a party to four U.S. collective bargaining agreements. The agreements will expire July 2015, October 2016, June 2017, and February 2018, respectively. The Company intends to renegotiate these contracts as they become due, though there is no assurance that this effort will be successful.

Restructuring_Asset_Impairment

Restructuring, Asset Impairment, and Transition Expenses	12 Months Ended
	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
Restructuring, Asset Impairment, and Transition Expenses	Restructuring, Asset Impairment, and Transition Expenses
	From time to time, the Company will initiate various restructuring programs and incur severance and other restructuring costs.
	The following table details restructuring charges incurred by segment for the periods presented:
		2014			2013		2012
	Clutches and Brakes	$	916		$	373	$	393
	Couplings	142			234		74
	Gearing and Power Transmission Components	603			504		2,729
	Corporate	106			—		—
	Total	$	1,767		$	1,111	$	3,196
	These amounts related to staff reductions and are classified in the Consolidated Statements of Income as restructuring expense in the respective periods.
	In the quarter ended December 31, 2012, the Company adopted the 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 during 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 following is a reconciliation of the accrued restructuring costs between January 1, 2012 and December 31, 2014:
		All Plans
	Balance at January 1, 2012	$	90
	Restructuring expense incurred	3,196
	Cash payments	(471		)
	Balance at January 1, 2013	2,815
	Restructuring expense incurred	1,111
	Cash payments	(3,497		)
	Balance at December 31, 2013	429
	Restructuring expense incurred	1,767
	Cash payments	(1,807		)
	Balance at December 31, 2014	$	389
	The total accrued restructuring reserve as of December 31, 2014 relates to severance costs to be paid to employees in 2015 and is recorded in accruals and other current liabilities on the consolidated balance sheet. The Company does not expect to incur any additional restructuring expenses in 2015 under the 2014 Altra Plan.

Derivative_Financial_Instrumen

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	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 $82.5 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 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 year ended December 31, 2014, nor was any amount excluded from ineffectiveness testing for these periods.
	The fair value of the swap recognized in other non-current assets and in other comprehensive income (loss) is as follows (in thousands):
							Fair Value
	Effective Date	Notional		Fixed		Maturity	December 31,		December 31,
		Amount		Rate			2014		2013
	April 30, 2013	$	82,500	0.626	%	November 30, 2016	$	143	$	135

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Minimum Lease Obligations
	The Company leases certain offices, warehouses, manufacturing facilities, automobiles and equipment with various terms that range from a month to month basis to 10 years terms and which, generally, include renewal provisions. Future minimum rent obligations under non-cancelable operating and capital leases are as follows:
	Year ending December 31:	Operating Leases		Capital Leases
	2015	$	6,891	$	115
	2016	5,816		115
	2017	4,546		115
	2018	2,538		115
	2019	1,873		38
	Thereafter	6,951		—
	Total lease obligations	$	28,615	$	498
	Less amounts representing interest			(22		)
	Present value of minimum capital lease obligations			$	476
	Net rent expense under operating leases for the years ended December 31, 2014, 2013, and 2012 was approximately $8.8 million, $8.8 million, $7.8 million, respectively.
	The Company also has minimum purchase contracts for inventory of €3.6 million ($4.4 million) for the year ended December 31, 2015.
	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. 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. 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.
	Our estimates regarding potential losses and materiality are based on our judgment and assessment of the claims utilizing currently available information. Although we will continue to reassess our reserves and estimates based on future developments, our objective assessment of the legal merits of such claims may not always be predictive of the outcome and actual results may vary from our current estimates. We will continue to consider the applicable guidance in ASC 450-20, based on the facts known at the time of our future filings, as it relates to legal contingencies, and will adjust our disclosures as may be required under the guidance.
	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. 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 consolidated balance sheets for potential litigation as of December 30, 2014 or December 31, 2013.
	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.
	Environmental
	There is contamination at some of the Company’s current facilities, primarily related to historical operations at those sites, for which the Company could be liable for the investigation and remediation under certain environmental laws. The potential for contamination also exists at other of the Company current or former sites, based on historical uses of those sites. The Company currently is not undertaking any remediation or investigations and the costs or liability in connection with potential contamination conditions at these facilities cannot be predicted at this time because the potential existence of contamination has not been investigated or not enough is known about the environmental conditions or likely remedial requirements. Currently, other parties with contractual liability are addressing or have plans or obligations to address those contamination conditions that may pose a material risk to human health, safety or the environment. In addition, while the Company attempts to evaluate the risk of liability associated with these facilities at the time the Company acquired them, there may be environmental conditions currently unknown to the Company relating to prior, existing or future sites or operations or those of predecessor companies whose liabilities the Company may have assumed or acquired which could have a material adverse effect on the Company’s business.
	The Company is being indemnified, or expects to be indemnified by third parties subject to certain caps or limitations on the indemnification, for certain environmental costs and liabilities associated with certain owned or operated sites. Accordingly, based on the indemnification and the experience with similar sites of the environmental consultants who the Company has hired, the Company does not expect such costs and liabilities to have a material adverse effect on its business, operations or earnings. The Company cannot assure you, however, that those third parties will in fact satisfy their indemnification obligations. If those third parties become unable to, or otherwise do not, comply with their respective indemnity obligations, or if certain contamination or other liability for which the Company is obligated is not subject to these indemnities, the Company could become subject to significant liabilities.
	From time to time, the Company is notified that it is a potentially responsible party and may have liability in connection with off-site disposal facilities. To date, the Company has generally resolved matters involving off-site disposal facilities for a nominal sum but there can be no assurance that the Company will be able to resolve pending or future matters in a similar fashion.

Segment_and_Geographic_Informa

Segment and Geographic Information	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment and Geographic Information	Segment and Geographic Information
	Effective during the quarter ended December 31, 2014, the Company has reclassified the presentation of the information regarding its reportable segments to reflect a change from one reportable segment in prior periods to three reportable segments in 2014. Effective beginning with the quarter ended December 31, 2014, management has concluded it is more appropriate to report in three segments. The segment information for the 2013 and 2012 has been reclassified to conform to the current year presentation.
	The Company currently operates through three business segments that are aligned with key product types:
	•	Clutches and Brakes.    Clutches are devices which use mechanical, magnetic, hydraulic, pneumatic, or friction type connections to facilitate engaging or disengaging two rotating members. Brakes are combinations of interacting parts that work to slow or stop machinery.
	•	Couplings.    Couplings are the interface between two shafts, which enable power to be transmitted from one shaft to the other.
	•	Gearing and Power Transmission Components.    Gears reduce the output speed and increase the torque of an electric motor or engine to the level required to drive a particular piece of equipment. Power transmission components are used in a number of industries to generate, transfer or control motion from a power source to an application requiring rotary or linear motion.
	Segment financial information and a reconciliation of segment results to consolidated results follows:
		Years Ended December 31,
		2014			2013			2012
	Net Sales:
	Clutches & Brakes	$	426,293		$	336,616		$	334,901
	Couplings	134,464			125,169			128,705
	Gearings & Power Transmission Components	264,514			265,154			274,004
	Intra-segment eliminations	(5,454		)	(4,721		)	(5,620		)
	Net sales	$	819,817		$	722,218		$	731,990
	Income from operations:
	Segment earnings:
	Clutches & Brakes	53,386			48,150			50,570
	Couplings	16,091			15,021			18,146
	Gearings & Power Transmission Components	24,534			23,881			22,421
	Restructuring	(1,767		)	(1,111		)	(3,196		)
	Corporate expenses	(17,135		)	(14,362		)	(11,090		)
	Income from operations	75,109			71,579			76,851
	Other non-operating (income) expense:
	Net interest expense	11,994			10,586			40,790
	Other non-operating (income) expense, net	(3		)	1,657			1,702
		11,991			12,243			42,492
	Income before income taxes	63,118			59,336			34,359
	Provision for income taxes	22,936			19,151			10,154
	Net income	$	40,182		$	40,185		$	24,205
	(1) Certain expenses are maintained at the corporate level and not allocated to the segments. These include various administrative expenses related to the corporate headquarters, depreciation on capitalized software costs, non-capitalizable software implementation costs, acquisition related expenses and non-cash partial pension settlements. include executive
	and functional compensation costs, non-service pension costs, non-operating insurance expenses, and various administrative
	expenses relating to the corporate headquarters and acquisition costs.
	Selected information by segment (continued)
		Years Ended December 31,
		2014			2013			2012
	Depreciation and amortization:
	Clutches & Brakes	$	12,936		$	9,203		$	8,847
	Couplings	5,655			5,402			5,016
	Gearing & Power Transmission Components	11,061			11,126			11,891
	Corporate	2,485			2,193			1,622
	Total depreciation and amortization	$	32,137		$	27,924		$	27,376
	Purchase of Property, plant and equipment:
	Clutches & Brakes	$	8,865		$	6,382		$	8,386
	Couplings	3,384			3,270			10,031
	Gearing & Power Transmission Components	13,413			15,001			6,767
	Corporate	2,388			3,170			6,162
	Total purchases of Property, plant and equipment:	$	28,050		$	27,823		$	31,346
	Total assets:
	Clutches & Brakes	$	334,371		$	364,826		$	244,255
	Couplings	117,805			109,279			112,910
	Gearing & Power Transmission Components	190,771			198,715			202,543
	Corporate (2)	41,616			62,856			103,331
	Total assets	$	684,563		$	735,676		$	663,039
	(2) Corporate assets are primarily cash and cash equivalents, tax related asset accounts, certain capitalized software costs, property, plant and equipment and deferred financing costs.
	Geographic Information	Net Sales									Property, Plant and Equipment
		Year Ended
		December 31,			December 31,			December 31,			December 31,		December 31,
		2014			2013			2012			2014		2013
	North America	$	488,523		$	454,115		$	469,554		$	90,279	$	87,573
	Europe	255,049			216,636			216,485			51,708		54,533
	Asia and the rest of the world	76,245			51,467			45,951			14,379		15,429
	Total	$	819,817		$	722,218		$	731,990		$	156,366	$	157,535
	Net sales to third parties are attributed to the geographic regions based on the country in which the shipment originates. Amounts attributed to the geographic regions for property, plant and equipment are based on the location of the entity, which holds such assets.

Unaudited_Quarterly_Results_of

Unaudited Quarterly Results of Operations	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Unaudited Quarterly Results of Operations	Unaudited Quarterly Results of Operations:
	Year ended December 31, 2014
		Fourth		Third		Second		First
		Quarter		Quarter		Quarter		Quarter
	Net Sales	$	191,961	$	202,520	$	215,198	$	210,138
	Gross Profit	58,270		62,333		66,470		61,796
	Net income attributable to Altra Industrial Motion Corp.	9,059		6,946		12,797		11,365
	Earnings per share — Basic attributable to Altra Industrial Motion Corp.
	Net income	$	0.34	$	0.26	$	0.48	$	0.43
	Earnings per share — Diluted attributable to Altra Industrial Motion Corp.
	Net income	$	0.34	$	0.25	$	0.46	$	0.41
	Year ended December 31, 2013
		Fourth		Third		Second		First
		Quarter		Quarter		Quarter		Quarter
	Net Sales	$	180,530	$	175,443	$	181,095	$	185,150
	Gross Profit	51,805		53,658		54,419		55,499
	Net income attributable to Altra	7,205		10,501		10,689		11,880
	Industrial Motion Corp.
	Earnings per share — Basic
	Net income attributable to Altra Industrial Motion Corp.	$	0.27	$	0.39	$	0.4	$	0.44
	Earnings per share — Diluted
	Net income attributable to Altra Industrial Motion Corp.	$	0.27	$	0.39	$	0.4	$	0.44

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	In February 2015, the Company’s Board of Directors approved the grant of 111,437 shares of restricted common stock or in certain cases restricted stock units, under the 2014 Omnibus Incentive Plan.
	On February 11, 2015, the Company has declared a dividend of $0.12 per share for the quarter ended March 31, 2015, payable on April 2, 2015 to shareholders of record as of March 18, 2015.

Schedule_II_Valuation_and_Qual

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	ALTRA INDUSTRIAL MOTION CORP.
	SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS
	Reserve for Uncollectible Accounts:	Balance at		Additions		Deductions			Balance at
		Beginning of							End of Period
		Period
	For the year ended December 31, 2012	$	1,092	$	1,675	$	(207	)	$	2,560
	For the year ended December 31, 2013	$	2,560	$	733	$	(1,048	)	$	2,245
	For the year ended December 31, 2014	$	2,245	$	417	$	(360	)	$	2,302

Description_of_Business_and_Su1

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

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Preparation and Description of Business

Basis of Preparation and Description of Business

Headquartered in Braintree, Massachusetts, Altra Industrial Motion Corp. (the “Company”) 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 twelve 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 former wholly owned subsidiary, changed its name to Altra Power Transmission, Inc. In December 2014, Altra Power Transmission, Inc. was merged into Altra Industrial Motion Corp.

Principles of Consolidation

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

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 equivalent shares 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:

Year Ended December, 31

2014

2013

2012

Net income attributable to Altra Industrial Motion Corp.

$

40,167

$

40,275

$

24,293

Shares used in net income per common share — basic

26,713

26,766

26,656

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

612

—

—

Incremental shares of unvested restricted common stock

78

75

100

Shares used in net income per common share — diluted

27,403

26,841

26,756

Earnings per share:

Basic net income attributable to Altra Industrial Motion Corp.

$

1.5

$

1.5

$

0.91

Diluted net income attributable to Altra Industrial Motion Corp.

$

1.47

$

1.5

$

0.91

During the year ended December 31, 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 net income per share in the diluted earnings per share calculation above. The Company excluded 2,571,130 shares in 2014, 3,137,351 shares in 2013 and 3,094,706 shares in 2012 (amounts not in thousands) related to the Convertible Notes (See Note 9) from the above earnings per share calculation as these shares were anti-dilutive.

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 are carried at cost, which approximates fair value. Debt under the Company’s Credit Agreement with certain financial institutions including the Term Loan Facility of $133,697,000 and a Revolving Credit Facility of $200,000,000 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 $85.0 million at December 31, 2014 and 2013. The estimated fair value of the Convertible Notes at December 31, 2014 and 2013 was $99.0 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 December 31, 2014 and 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).

The estimated fair value of the Company’s interest rate swap agreement with certain financial institutions (“Interest Rate Swap”) as of December 31, 2014 and 2013 was $0.1 million and $0.1 million , 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.

Use of Estimates

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the financial statements. Actual results could differ from those estimates.

Non-Controlling Interest

Non-controlling Interest

On July 11, 2012, the Company acquired 85% of privately held Lamiflex do Brasil Equipamentos Industriais Ltda. (“Lamiflex”).

The Company recorded the redeemable non-controlling interest from its acquisition of an 85% ownership interest of Lamiflex at fair value at the date of acquisition. In connection with this acquisition, the Company entered into put and call option agreements with the minority shareholders for the potential purchase of the non-controlling interest at a future date at a value based on a contractually determined formula. As a result of the option agreements, the non-controlling interest is considered redeemable and is classified as temporary equity on the Company’s consolidated balance sheet. The non-controlling interest is reviewed at each subsequent reporting period and adjusted, as needed, to reflect its then redemption value.

Foreign Currency Translation

Foreign Currency Translation

Assets and liabilities of subsidiaries operating outside of the United States with a functional currency other than the U.S. Dollar are translated into U.S. Dollars using exchange rates at the end of the respective period. Revenues and expenses are translated at average exchange rates effective during the respective period.

Foreign currency translation adjustments are included in accumulated other comprehensive income as a separate component of stockholders’ equity. Net foreign currency transaction gains and losses are included in the results of operations in the period incurred and included in other non-operating expense (income), net in the accompanying statements of income.

Trade Receivables

Trade Receivables

An allowance for doubtful accounts is recorded for estimated collection losses that will be incurred in the collection of receivables. Estimated losses are based on historical collection experience, as well as a review by management of the status of all receivables. Collection losses have been within the Company’s expectations.

Inventories

Inventories

Inventories are stated at the lower of cost or market using the first-in, first-out (“FIFO”) method for all entities excluding one of the Company’s subsidiaries, TB Wood’s. TB Wood’s inventory is stated at the lower of cost or market, principally using the last-in, first-out (“LIFO”) method. Inventory stated using the LIFO method approximates 7.0% and 7.5% of total inventory at December 31, 2014 and 2013, respectively.

The cost of inventories acquired by the Company in its acquisitions reflect fair value at the date of acquisition as determined by the Company based on the replacement cost of raw materials, the sales price of the finished goods less an appropriate amount representing the expected profitability from selling efforts, and for work-in-process the sales price of the finished goods less an appropriate amount representing the expected profitability from selling efforts and costs to complete.

The Company periodically reviews its quantities of inventories on hand and compares these amounts to the expected usage of each particular product or product line. The Company records a charge to cost of sales for any amounts required to reduce the carrying value of inventories to its estimated net realizable value.

Property, Plant and Equipment

Property, Plant and Equipment

Property, plant and equipment are stated at cost, net of accumulated depreciation.

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

Leasehold improvements are depreciated on a straight-line basis over the estimated life of the asset or the life of the lease, if shorter.

Improvements and replacements are capitalized to the extent that they increase the useful economic life or increase the expected economic benefit of the underlying asset. Repairs and maintenance expenditures are charged to expense as incurred.

Intangible Assets

Intangible Assets

Intangible assets represent product technology, patents, tradenames, trademarks and customer relationships. Product technology, patents and customer relationships are amortized on a straight-line basis over 8 to 17 years, which approximates the period of economic benefit. The tradenames and trademarks are considered indefinite-lived assets and are not being amortized. Intangibles are stated at fair value on the date of acquisition. Intangibles are stated net of accumulated amortization.

Goodwill

Goodwill

Goodwill represents the excess of the purchase price paid by the Company over the fair value of the net assets acquired in each of the Company’s acquisitions.

Impairment of Goodwill and Indefinite-Lived Intangible Assets

Impairment of Goodwill and Indefinite-Lived Intangible Assets

The Company conducts an annual impairment review of goodwill and indefinite-lived intangible assets in December of each year, unless events occur which trigger the need for an interim impairment review.

In connection with the Company’s annual impairment review, goodwill is assessed for impairment by comparing the fair value of the reporting unit to the carrying value using a two-step approach. In the first step, the Company estimates future cash flows based upon historical results and current market projections, discounted at a market comparable rate. If the carrying amount of the reporting unit exceeds the estimated fair value, impairment may be present, the Company would then be required to perform a second step in its impairment analysis. In the second step, the Company would evaluate impairment losses based upon the fair value of the underlying assets and liabilities of the reporting unit, including any unrecognized intangible assets, and estimate the implied fair value of the goodwill. An impairment loss is recognized to the extent that a reporting unit’s recorded value of the goodwill asset exceeded its deemed fair value. In addition, to the extent the implied fair value of any indefinite-lived intangible asset is less than the asset’s carrying value, an impairment loss is recognized on those assets. The Company did not identify any impairment of goodwill during the periods presented.

For our indefinite-lived intangible assets, mainly trademarks, we estimated the fair value first by estimating the total revenue attributable to the trademarks for each of the reporting units. Second, we estimated an appropriate royalty rate using the return on assets method by estimating the required financial return on our assets, excluding trademarks, less the overall return generated by our total asset base. The return as a percentage of revenue provides an indication of our royalty rate (between 1.0% and 1.25%). We compared the estimated fair value of our trademarks with the carrying value of the trademarks and did not identify any impairment. The Company did not identify any impairment of indefinite-lived intangible assets during the periods presented.

Preparation of forecasts of revenue and profitability growth for use in the long-range plan and the discount rate require significant use of judgment. Changes to the discount rate and the forecasted profitability could affect the estimated fair value of one or more of the Company’s reporting units and could result in a goodwill impairment charge in a future period.

Impairment of Long-Lived Assets Other Than Goodwill and Indefinite-Lived Intangible Assets

Impairment of Long-Lived Assets Other Than Goodwill and Indefinite-Lived Intangible Assets

Long-lived assets, including definite-lived intangible assets, are reviewed for impairment when events or circumstances indicate that the carrying amount of a long-lived asset may not be recovered. Long-lived assets are considered to be impaired if the carrying amount of the asset exceeds the undiscounted future cash flows expected to be generated by the asset over its remaining useful life. If an asset is considered to be impaired, the impairment is measured by the amount by which the carrying amount of the asset exceeds its fair value, and is charged to results of operations at that time.

The Company did not identify any impairment of long-lived assets in the periods presented.

Determining fair values based on discounted cash flows requires management to make significant estimates and assumptions, including forecasting of revenue and profitability growth for use in the long-range plan and estimating appropriate discount rates. Changes to the discount rate and the forecasted profitability could affect the estimated fair value of one or more of the Company’s indefinite-lived intangible assets and could result in an impairment charge in a future period.

Debt Issuance Costs

Debt Issuance Costs

Costs directly related to the issuance of debt are capitalized, included in other non-current assets and amortized using the effective interest method over the term of the related debt obligation. The net carrying value of debt issuance costs was approximately $3.2 million and $4.1 million at December 31, 2014 and 2013, respectively.

Revenue Recognition

Revenue Recognition

Product revenues are recognized, net of sales tax collected, at the time title and risk of loss pass to the customer, which generally occurs upon shipment to the customer. Product return reserves are accrued at the time of sale based on the historical relationship between shipments and returns, and are recorded as a reduction of net sales.

Certain large distribution customers receive annual volume discounts, which are estimated at the time the sale is recorded based on the estimated annual sales.

Shipping and Handling Costs

Shipping and Handling Costs

Shipping and handling costs associated with sales are classified as a component of cost of sales.

Warranty Costs

Warranty Costs

Estimated expenses related to product warranties are accrued at the time products are sold to customers. Estimates are established using historical information as to the nature, frequency, and average costs of warranty claims. See Note 6 to the consolidated financial statements.

Self-Insurance

Self-Insurance

Certain exposures are self-insured up to pre-determined amounts, above which third-party insurance applies, for medical claims, workers’ compensation, vehicle insurance, product liability costs and general liability exposure. The accompanying balance sheets include reserves for the estimated costs associated with these self-insured risks, based on historic experience factors and management’s estimates for known and anticipated claims. A portion of medical insurance costs are offset by charging employees a premium equivalent to group insurance rates.

Research and Development

Research and Development

Research and development costs are expensed as incurred.

Advertising

Advertising

Advertising costs are charged to selling, general and administrative expenses as incurred and amounted to approximately $2.9 million, $2.5 million and $2.1 million, for the years ended December 31, 2014, 2013, and 2012, respectively.

Stock-Based Compensation

Stock-Based Compensation

The Company's 2004 Equity Incentive Plan (the “2004 Plan”) permitted the grant of various forms of stock based compensation to our officers and senior level employees.  The 2004 Plan expired in 2014 and, upon expiration, there were 750,576 shares subject to outstanding awards under the 2004 Plan.  The 2014 Omnibus Incentive Plan (the “2014 Plan”) was approved by the Company's shareholders at its 2014 annual meeting.  The 2014 Plan provides for various forms of stock based compensation to our directors, executive personnel and other key employees and consultants. Under the 2014 Plan, the total number of shares of common stock available for delivery pursuant to the grant of awards (“Awards”) was originally 750,000. Shares of our common stock subject to Awards or awarded under the 2004 Plan and outstanding as of the effective date of the 2014 Plan (except for substitute awards) that terminate without being exercised, expire, are forfeited or canceled, are exchanged for Awards that did not involve shares of common stock, are not issued on the stock settlement of a stock appreciation right, are withheld by the Company or tendered by a participant (either actually or by attestation) to pay an option exercise price or to pay the withholding tax on any Award, or are settled in cash in lieu of shares will again be available for Awards under the 2014 Plan. The Company recognizes stock based compensation expense on a straight line basis for shares vesting ratably under the 2004 Plan and 2014 Plan and uses the graded-vesting method of recognizing stock-based compensation expense for performance share awards based on the probability of the specific performance metrics being achieved over the requisite service period.

Income Taxes

Income Taxes

The Company records income taxes using the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and operating loss and tax credit carryforwards. The Company evaluates the realizability of its net deferred tax assets and assesses the need for a valuation allowance on a quarterly basis. The future benefit to be derived from its deferred tax assets is dependent upon the Company’s ability to generate sufficient future taxable income to realize the assets. The Company records a valuation allowance to reduce its net deferred tax assets to the amount that may be more likely than not to be realized.

To the extent the Company establishes a valuation allowance on net deferred tax assets generated from operations, an expense will be recorded within the provision for income taxes. In periods subsequent to establishing a valuation allowance on net deferred assets from operations, if the Company were to determine that it would be able to realize its net deferred tax assets in excess of their net recorded amount, an adjustment to the valuation allowance would be recorded as a reduction to income tax expense in the period such determination was made.

We assess our income tax positions and record tax benefits for all years subject to examination, based upon our evaluation of the facts, circumstances and information available at the reporting date. For those tax positions for which it is more likely than not that a tax benefit will be sustained, we record the amount that has a greater than 50% likelihood of being realized upon settlement with the taxing authority that has full knowledge of all relevant information. Interest and penalties are related to unrecognized tax benefits in income tax expense in the consolidated statement of income and included in accruals and other long-term liabilities in the Company's consolidated balance sheet, where applicable. If we do not believe that it is more likely than not that a tax benefit will be sustained, no tax benefit is recognized.

Contingencies Policy

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. 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. 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.

Our estimates regarding potential losses and materiality are based on our judgment and assessment of the claims utilizing currently available information. Although we will continue to reassess our reserves and estimates based on future developments, our objective assessment of the legal merits of such claims may not always be predictive of the outcome and actual results may vary from our current estimates. We will continue to consider the applicable guidance in ASC 450-20, based on the facts known at the time of our future filings, as it relates to legal contingencies, and will adjust our disclosures as may be required under the guidance.

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. 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 consolidated balance sheets for potential litigation as of December 30, 2014 or December 31, 2013.

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.

Changes in Accumulated Other Comprehensive Loss by Component

Changes in Accumulated Other Comprehensive Loss by Component

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

Interest Rate Swap

Defined

Cumulative

Total

Benefit

Foreign

Pension Plans

Currency

Translation

Accumulated Other Comprehensive Loss by Component, January 1, 2012

$

—

$

(2,485

)

$

(22,591

)

$

(25,076

)

Net current-period Other Comprehensive Income

—

(2,122

)

3,795

1,673

Accumulated Other Comprehensive Loss by Component, January 1, 2013

—

(4,607

)

(18,796

)

(23,403

)

Net current-period Other Comprehensive Income

135

1,474

3,398

5,007

Accumulated Other Comprehensive Income (Loss) by component, January 1, 2014

135

(3,133

)

(15,398

)

(18,396

)

Net current-period Other Comprehensive Income (Loss)

8

(1,685

)

(21,342

)

(23,019

)

Accumulated Other Comprehensive Income (Loss) by component, December 31, 2014

$

143

$

(4,818

)

$

(36,740

)

$

(41,415

)

Description_of_Business_and_Su2

Description of Business and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reconciliation of Basic to Diluted Net Income Per Share	The following is a reconciliation of basic to diluted net income per share:
		Year Ended December, 31
		2014		2013			2012
	Net income attributable to Altra Industrial Motion Corp.	$	40,167	$	40,275		$	24,293
	Shares used in net income per common share — basic	26,713		26,766			26,656
	Dilutive effect of the equity premium on Convertible Notes at the average price of common stock	612		—			—
	Incremental shares of unvested restricted common stock	78		75			100
	Shares used in net income per common share — diluted	27,403		26,841			26,756
	Earnings per share:
	Basic net income attributable to Altra Industrial Motion Corp.	$	1.5	$	1.5		$	0.91
	Diluted net income attributable to Altra Industrial Motion Corp.	$	1.47	$	1.5		$	0.91
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:
		Interest Rate Swap		Defined			Cumulative			Total
				Benefit			Foreign
				Pension Plans			Currency
							Translation
	Accumulated Other Comprehensive Loss by Component, January 1, 2012	$	—	$	(2,485	)	$	(22,591	)	$	(25,076	)
	Net current-period Other Comprehensive Income	—		(2,122		)	3,795			1,673
	Accumulated Other Comprehensive Loss by Component, January 1, 2013	—		(4,607		)	(18,796		)	(23,403		)
	Net current-period Other Comprehensive Income	135		1,474			3,398			5,007
	Accumulated Other Comprehensive Income (Loss) by component, January 1, 2014	135		(3,133		)	(15,398		)	(18,396		)
	Net current-period Other Comprehensive Income (Loss)	8		(1,685		)	(21,342		)	(23,019		)
	Accumulated Other Comprehensive Income (Loss) by component, December 31, 2014	$	143	$	(4,818	)	$	(36,740	)	$	(41,415	)

Acquisitions_Tables

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2014
Proforma Amount on Acquisition Occurred
		2014		2013			2012
	Total revenues	$	825,723	$	813,477		$	818,956
	Net income attributable to Altra Industrial Motion Corp.	$	42,632	$	38,695		$	22,373
	Basic earnings per share:
	Net income attributable to Altra Industrial Motion Corp.	$	1.6	$	1.45		$	0.84
	Diluted earnings per share:
	Net income attributable to Altra Industrial Motion Corp.	$	1.56	$	1.44		$	0.84
Svendborg [Member]
Preliminary Purchase Price Allocation as of Acquisition Date	The Company updated the acquisition accounting for the measurement period adjustments noted in the table below during the year ended December 31, 2014.
		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		(715		)	20,860
	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		(1,015		)	121,248
	Accounts payable	4,833		—			4,833
	Accrued expenses and other current liabilities	9,620		517			10,137
	Taxes payable	10,254		—			10,254
	Deferred tax liability	11,483		431			11,914
	Total liabilities assumed	36,190		948			37,138
	Net assets acquired	86,073		(1,963		)	84,110
	Excess of purchase price over fair value of net assets acquired	$	16,023	$	1,963		$	17,986
Amounts Recorded as Intangible Assets
	Customer relationships, subject to amortization	$	40,050
	Trade names and trademarks, not subject to amortization	8,500
	Patents	343
	Total intangible assets	$	48,893
Guardian [Member]
Preliminary Purchase Price Allocation as of Acquisition Date	On July 1, 2014, the Company acquired all of the issued and outstanding shares of Guardian Ind., Inc. (“Guardian Couplings”) for cash consideration of $17.1 million. This transaction is referred to as the Guardian Acquisition. Guardian Couplings is a manufacturer and supplier of flywheel, motion control and general industrial couplings. The Guardian Acquisition provides the Company with increased product coverage in several core markets, including energy, farm and agriculture, and specialty machinery and is expected to provide synergies with the Company's existing product offerings.
	The sellers agreed to provide the Company with a limited set of representations and warranties, including those with respect to outstanding and potential liabilities. Claims for a breach of a representation or warranty are secured by a limited escrow. There is no guarantee that the Company would actually be able to recover all or any portion of the sums payable in connection with such breach.
	The Company is in the process of finalizing the valuation of certain intangibles, the related tax impact and the valuation of certain tax information to finalize fair value. The Company believes that such preliminary allocations provide a reasonable basis for estimating the fair values of assets acquired and liabilities assumed. The purchase price of $17.1 million, excluding acquisition costs of $0.2 million, is in excess of the fair value of net assets acquired by approximately $2.2 million. Current assets acquired, excluding approximately $2.0 million in cash, totaled approximately $4.0 million, non-current assets totaled approximately $9.2 million and current liabilities totaled approximately $0.3 million.
	The excess of the purchase price over the fair value of the net assets acquired was recorded as goodwill. This goodwill is deductible for income tax purposes over a period of 15 years. The Company expects to develop synergies, such as lower cost country sourcing and global procurement.
Amounts Recorded as Intangible Assets

Inventories_Tables

Inventories (Tables)	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Summary of Inventories	Inventories consisted of the following:
		December 31,		December 31,
		2014		2013
	Raw materials	$	36,814	$	56,824
	Work in process	13,641		18,432
	Finished goods	82,281		68,409
	Inventories, net	$	132,736	$	143,665

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	Property, plant and equipment consisted of the following:
		2014			2013
	Land	$	26,560		$	20,803
	Buildings and improvements	44,791			53,078
	Machinery and equipment	220,896			207,193
		292,247			281,074
	Less-Accumulated depreciation	(135,881		)	(123,539		)
		$	156,366		$	157,535

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in Goodwill	The changes in the carrying value of goodwill by segment for the years ended December 31, 2014 and 2013 are as follows:
		Clutches and Brakes			Couplings			Gearing & Power Transmission Components			Total
	Gross goodwill balance as of January 1, 2013	$	37,784		$	36,138		$	46,113		$	120,035
	Accumulated Impairment January 1, 2013	(3,745		)	(14,982		)	(13,083		)	(31,810		)
	Purchase price accounting adjustments	16,023			—			—			16,023
	Impact of changes in foreign currency and other	418			(414		)	87			91
	Net goodwill balance December 31, 2013	50,480			20,742			33,117			104,339
	Purchase price accounting adjustments	1,963			2,180			—			4,143
	Impact of changes in foreign currency and other	(4,741		)	(512		)	(1,142		)	(6,395		)
	Net goodwill balance December 31, 2014	$	47,702		$	22,410		$	31,975		$	102,087
Intangibles and Related Accumulated Amortization	The following table provides the gross carrying value and accumulated amortization for each major class of intangible asset:
		December 31, 2014												December 31, 2013
		Cost				Accumulated				Net				Cost		Accumulated		Net
						Amortization										Amortization
	Intangible Assets
	Intangible assets not subject to amortization:
	Tradenames and trademarks	$	41,257			$	—			$	41,257			$	42,605	$	—	$	42,605
	Intangible assets subject to amortization:
	Customer relationships	118,523				49,849				68,674				117,848		42,582		75,266
	Product technology and patents	6,830				6,031				799				6,983		6,086		897
	Total intangible assets	$	166,610			$	55,880			$	110,730			$	167,436	$	48,668	$	118,768

Warranty_Costs_Tables

Warranty Costs (Tables)	12 Months Ended
	Dec. 31, 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 years ended December 31, are as follows:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Balance at beginning of period	$	8,739		$	5,625		$	4,898
	Accrued current period warranty costs	1,537			2,573			2,386
	Acquired warranty reserves	—			3,420			—
	Payments and adjustments	(2,484		)	(2,879		)	(1,659		)
	Balance at end of period	$	7,792		$	8,739		$	5,625

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Before Income Taxes by Domestic and Foreign Locations	Income before income taxes by domestic and foreign locations consists of the following:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Domestic	$	33,065		$	37,640		$	18,083
	Foreign	30,053			21,696			16,276
	Total	$	63,118		$	59,336		$	34,359
Components of Provision (Benefit) for Income Taxes	The components of the provision for income taxes consist of the following:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Current:
	Federal	$	12,545		$	8,917		$	8,370
	State	299			698			(3,597		)
	Non-US	7,380			6,072			6,006
		20,224			15,687			10,779
	Deferred:
	Federal	2,673			3,533			(915		)
	State	198			378			1,756
	Non-US	(159		)	(447		)	(1,466		)
		2,712			3,464			(625		)
	Provision for income taxes	$	22,936		$	19,151		$	10,154
Reconciliation from Tax at U.S. Federal Statutory Rate to Company's Provision (Benefit) for Income Taxes	A reconciliation from tax at the U.S. federal statutory rate to the Company’s provision for income taxes is as follows:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Tax at US federal income tax rate	$	22,092		$	20,767		$	12,026
	State taxes, net of federal income tax effect	495			905			67
	Change in tax rate	11			(354		)	(267		)
	Foreign reorganization	3,786			—			—
	Foreign taxes	(1,978		)	(224		)	781
	Adjustments to accrued income tax liabilities and uncertain tax positions	(287		)	(52		)	(1,289		)
	Valuation allowance	612			120			506
	Intercompany interest	(910		)	(986		)	(1,676		)
	Tax credits and incentives	(666		)	(816		)	(291		)
	Domestic manufacturing deduction	(1,201		)	(839		)	(566		)
	Other	982			630			863
	Provision for income taxes	$	22,936		$	19,151		$	10,154
Reconciliation of Gross Amount of Unrecognized Tax Benefits Excluding Accrued Interest and Penalties	A reconciliation of the gross amount of unrecognized tax benefits excluding accrued interest and penalties is as follows:
		December 31,			December 31,			December 31,
		2014			2013			2012
	Balance at beginning of period	$	627		$	747		$	3,523
	Increases related to prior year tax positions	—			—			—
	Decreases related to prior year tax positions	—			(33		)	—
	Increases related to current year tax positions	—			—			—
	Settlements	(176		)	—			(2,689		)
	Lapse of statute of limitations	(17		)	(87		)	(87		)
	Balance at end of period	$	434		$	627		$	747
Significant Components of Deferred Tax Assets and Liabilities	Significant components of the deferred tax assets and liabilities as of December 31, 2014 and 2013 are as follows:
		2014			2013
	Deferred tax assets:
	Post-retirement obligations	$	1,363		$	1,565
	Tax credits	2,194			2,165
	Expenses not currently deductible	11,457			11,788
	Net operating loss carryover	5,901			6,376
	Other	519			546
	Total deferred tax assets	21,434			22,440
	Valuation allowance for deferred tax assets	(5,974		)	(5,577		)
	Net deferred tax assets	15,460			16,863
	Deferred tax liabilities:
	Property, plant and equipment	19,002			20,065
	Intangible assets	22,735			25,090
	Basis difference - convertible debt	11,875			11,064
	Goodwill	4,967			3,813
	Total deferred liabilities	58,579			60,032
	Net deferred tax liabilities	$	43,119		$	43,169

Pension_and_Other_Employee_Ben1

Pension and Other Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 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 benefit obligation, fair value of plan assets and funded status of the respective defined benefit (pension) plans as of December 31, 2014 and 2013:
		Pension Benefits
		Year Ended				Year Ended
		December 31,				December 31,
		2014				2013
	Change in benefit obligation:
	Obligation at beginning of period	$	32,215			$	34,629
	Partial settlement gain	(582		)		—
	Service cost	243				248
	Interest cost	1,353				1,250
	Partial settlement payments	(2,080		)		—
	Actuarial (gains) losses	5,978				(2,969		)
	Foreign exchange effect	(909		)		343
	Benefits paid	(1,357		)		(1,286		)
	Obligation at end of period	$	34,861			$	32,215
	Change in plan assets:
	Fair value of plan assets, beginning of period	$	24,190			$	20,100
	Partial settlement payments	(2,080		)		—
	Actual return on plan assets	3,668				182
	Employer contributions	447				5,194
	Benefits paid	(1,357		)		(1,286		)
	Fair value of plan assets, end of period	$	24,868			$	24,190
	Funded status	$	(9,993	)		$	(8,025	)
	Amounts Recognized in the balance sheet consist of:
	Non-current liabilities	$	(9,993	)		$	(8,025	)
	Total	$	(9,993	)		$	(8,025	)
Discount Rate Used in Computation of Respective Benefit Obligations	The discount rate used in the computation of the respective benefit obligations at December 31, 2014 and 2013, presented above are as follows:
		2014			2013
	Pension benefits	3.7	%		4.6	%
Components of Net Periodic Benefit Cost	The following table represents the components of the net periodic benefit cost associated with the respective plans:
		Pension Benefits
		Year Ended				Year Ended				Year Ended
		December 31,				December 31,				December 31,
		2014				2013				2012
	Service cost	$	243			$	248			$	179
	Interest cost	1,353				1,250				1,381
	Expected return on plan assets	(1,084		)		(1,080		)		(1,083		)
	Non-cash impact of partial pension settlement	475				—				—
	Amortization of actuarial losses	159				175				105
	Net periodic benefit cost	$	1,146			$	593			$	582
Economic Assumptions Used in Computation of Respective Net Periodic Benefit Cost	The key economic assumptions used in the computation of the respective net periodic benefit cost for the periods presented above are as follows:
		Pension Benefits
		Year Ended			Year Ended			Year Ended
		December 31,			December 31,			December 31,
		2014			2013			2012
	Discount rate	4.6	%		3.75	%		4.75	%
	Expected return on plan assets	4.6	%		5.25	%		6.25	%
Schedule of Fair Value of Pension Plan Assets	The fair value of the Company’s pension plan assets at December 31, 2014 and 2013 by asset category is as follows:
		2014				2013
	Asset Category
	Fixed income (Level 1)
	U.S. government	3,554				2,787
	Corporate bonds
	Investment grade	17,682				17,091
	High yield	3,090				3,634
	Total fixed income	24,326				23,512
	Other (Level 2)	286				338
	Cash and cash equivalents (Level 1)	256				340
	Total assets at fair value	$	24,868			$	24,190
Schedule of Asset Allocations for Funded Retirement Plan	The asset allocations for the Company’s funded retirement plan at December 31, 2014 and 2013, respectively, and the target allocation for 2014, by asset category, are as follows:
		Allocation Percentage of
		Plan Assets at Year-End
		2014			2014		2013
		Actual			Target		Actual
	Asset Category
	Investment Grade Bonds	86	%		70% - 100%		84	%
	High Yield Bonds	13	%		0% - 25%		15	%
	Cash	1	%		0% - 5%		1	%
Summary of Amounts of Expected Benefit Payments	The following table provides the amounts of expected benefit payments, which are made from the plans’ assets and includes the participants’ share of the costs, which is funded by participant contributions. The amounts in the table are actuarially determined and reflect the Company’s best estimate given its current knowledge; actual amounts could be materially different.
		Pension
		Benefits
	Expected benefit payments (from plan assets)
	2015	1,287
	2016	1,366
	2017	1,409
	2018	1,488
	2019	1,564
	Thereafter	7,858

LongTerm_Debt_Tables

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Outstanding Debt Obligations
		December 31,				December 31,
		2014				2013
	Debt:
	Revolving Credit Facility	$	40,000			$	41,198
	Convertible Notes	85,000				85,000
	Term Loan Facility	133,697				163,245
	Bauer Mortgage	3,647				—
	Equipment Loan	5,430				4,155
	Mortgages	258				659
	Capital leases	476				178
	Total debt	268,508				294,435
	Less: debt discount, net of accretion	(12,756		)		(16,163		)
	Total debt, net of unaccreted discount	255,752				278,272
	Less current portion of long-term debt	(15,176		)		(16,924		)
	Total long-term debt	$	240,576			$	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 December 31, 2014:
		December 31,
		2014
	Principal amount of debt	$	85,000
	Unamortized discount	12,756
	Carrying value of debt	$	72,244
Interest Expense Associated with Convertible Notes	Interest expense associated with the Convertible Notes consisted of the following :
		December 31,			December 31,			December 31,
		2014			2013			2012
	Contractual coupon rate of interest	$	2,338		$	2,338		$	2,338
	Accretion of Convertible Notes discount and amortization of deferred financing costs	3,760			3,494			3,239
	Interest expense for the Convertible Notes	$	6,098		$	5,832		$	5,577

Stockholders_Equity_Tables

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Schedule of Activity of Company's Restricted Stock Grants	The following table sets forth the activity of the Company’s restricted stock grants to date:
	Amounts not in thousands	Shares		Weighted-
				Average Grant
				Date Fair Value
	Restricted shares unvested January 1, 2014	149,635		$	23.02
	Shares granted	136,340		$	33.52
	Shares for which restrictions lapsed	(126,797	)	$	29.58
	Restricted shares unvested December 31, 2014	159,178		$	28.53

Restructuring_Asset_Impairment1

Restructuring, Asset Impairment, and Transition Expenses (Tables)	12 Months Ended
	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
Summary of Total Restructuring Expense	The following table details restructuring charges incurred by segment for the periods presented:
		2014			2013		2012
	Clutches and Brakes	$	916		$	373	$	393
	Couplings	142			234		74
	Gearing and Power Transmission Components	603			504		2,729
	Corporate	106			—		—
	Total	$	1,767		$	1,111	$	3,196
Reconciliation of Accrued Restructuring Costs	The following is a reconciliation of the accrued restructuring costs between January 1, 2012 and December 31, 2014:
		All Plans
	Balance at January 1, 2012	$	90
	Restructuring expense incurred	3,196
	Cash payments	(471		)
	Balance at January 1, 2013	2,815
	Restructuring expense incurred	1,111
	Cash payments	(3,497		)
	Balance at December 31, 2013	429
	Restructuring expense incurred	1,767
	Cash payments	(1,807		)
	Balance at December 31, 2014	$	389

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Swap Recognized in Other Non-Current Assets and in Other Comprehensive Income (Loss)	The fair value of the swap recognized in other non-current assets and in other comprehensive income (loss) is as follows (in thousands):
							Fair Value
	Effective Date	Notional		Fixed		Maturity	December 31,		December 31,
		Amount		Rate			2014		2013
	April 30, 2013	$	82,500	0.626	%	November 30, 2016	$	143	$	135

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Rent Obligations under Non-Cancelable Operating and Capital Leases	Future minimum rent obligations under non-cancelable operating and capital leases are as follows:
	Year ending December 31:	Operating Leases		Capital Leases
	2015	$	6,891	$	115
	2016	5,816		115
	2017	4,546		115
	2018	2,538		115
	2019	1,873		38
	Thereafter	6,951		—
	Total lease obligations	$	28,615	$	498
	Less amounts representing interest			(22		)
	Present value of minimum capital lease obligations			$	476

Segment_and_Geographic_Informa1

Segment and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Reconciliation of Revenue from Segments to Consolidated
	Segment financial information and a reconciliation of segment results to consolidated results follows:
		Years Ended December 31,
		2014			2013			2012
	Net Sales:
	Clutches & Brakes	$	426,293		$	336,616		$	334,901
	Couplings	134,464			125,169			128,705
	Gearings & Power Transmission Components	264,514			265,154			274,004
	Intra-segment eliminations	(5,454		)	(4,721		)	(5,620		)
	Net sales	$	819,817		$	722,218		$	731,990
	Income from operations:
	Segment earnings:
	Clutches & Brakes	53,386			48,150			50,570
	Couplings	16,091			15,021			18,146
	Gearings & Power Transmission Components	24,534			23,881			22,421
	Restructuring	(1,767		)	(1,111		)	(3,196		)
	Corporate expenses	(17,135		)	(14,362		)	(11,090		)
	Income from operations	75,109			71,579			76,851
	Other non-operating (income) expense:
	Net interest expense	11,994			10,586			40,790
	Other non-operating (income) expense, net	(3		)	1,657			1,702
		11,991			12,243			42,492
	Income before income taxes	63,118			59,336			34,359
	Provision for income taxes	22,936			19,151			10,154
	Net income	$	40,182		$	40,185		$	24,205
	(1) Certain expenses are maintained at the corporate level and not allocated to the segments. These include various administrative expenses related to the corporate headquarters, depreciation on capitalized software costs, non-capitalizable software implementation costs, acquisition related expenses and non-cash partial pension settlements. include executive
	and functional compensation costs, non-service pension costs, non-operating insurance expenses, and various administrative
	expenses relating to the corporate headquarters and acquisition costs.
Reconciliation of Assets from Segment to Consolidated
		Years Ended December 31,
		2014			2013			2012
	Depreciation and amortization:
	Clutches & Brakes	$	12,936		$	9,203		$	8,847
	Couplings	5,655			5,402			5,016
	Gearing & Power Transmission Components	11,061			11,126			11,891
	Corporate	2,485			2,193			1,622
	Total depreciation and amortization	$	32,137		$	27,924		$	27,376
	Purchase of Property, plant and equipment:
	Clutches & Brakes	$	8,865		$	6,382		$	8,386
	Couplings	3,384			3,270			10,031
	Gearing & Power Transmission Components	13,413			15,001			6,767
	Corporate	2,388			3,170			6,162
	Total purchases of Property, plant and equipment:	$	28,050		$	27,823		$	31,346
	Total assets:
	Clutches & Brakes	$	334,371		$	364,826		$	244,255
	Couplings	117,805			109,279			112,910
	Gearing & Power Transmission Components	190,771			198,715			202,543
	Corporate (2)	41,616			62,856			103,331
	Total assets	$	684,563		$	735,676		$	663,039
	(2) Corporate assets are primarily cash and cash equivalents, tax related asset accounts, certain capitalized software costs, property, plant and equipment and deferred financing costs.
Geographical Information - Net Sales
	Geographic Information	Net Sales									Property, Plant and Equipment
		Year Ended
		December 31,			December 31,			December 31,			December 31,		December 31,
		2014			2013			2012			2014		2013
	North America	$	488,523		$	454,115		$	469,554		$	90,279	$	87,573
	Europe	255,049			216,636			216,485			51,708		54,533
	Asia and the rest of the world	76,245			51,467			45,951			14,379		15,429
	Total	$	819,817		$	722,218		$	731,990		$	156,366	$	157,535
	Net sales to third parties are attributed to the geographic regions based on the country in which the shipment originates. Amounts attributed to the geographic regions for property, plant and equipment are based on the location of the entity, which holds such assets.
Geographical Information - Property, Plant and Equipment
	Geographic Information	Net Sales									Property, Plant and Equipment
		Year Ended
		December 31,			December 31,			December 31,			December 31,		December 31,
		2014			2013			2012			2014		2013
	North America	$	488,523		$	454,115		$	469,554		$	90,279	$	87,573
	Europe	255,049			216,636			216,485			51,708		54,533
	Asia and the rest of the world	76,245			51,467			45,951			14,379		15,429
	Total	$	819,817		$	722,218		$	731,990		$	156,366	$	157,535
	Net sales to third parties are attributed to the geographic regions based on the country in which the shipment originates. Amounts attributed to the geographic regions for property, plant and equipment are based on the location of the entity, which holds such assets.

Unaudited_Quarterly_Results_of1

Unaudited Quarterly Results of Operations (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Results of Operations	Unaudited Quarterly Results of Operations:
	Year ended December 31, 2014
		Fourth		Third		Second		First
		Quarter		Quarter		Quarter		Quarter
	Net Sales	$	191,961	$	202,520	$	215,198	$	210,138
	Gross Profit	58,270		62,333		66,470		61,796
	Net income attributable to Altra Industrial Motion Corp.	9,059		6,946		12,797		11,365
	Earnings per share — Basic attributable to Altra Industrial Motion Corp.
	Net income	$	0.34	$	0.26	$	0.48	$	0.43
	Earnings per share — Diluted attributable to Altra Industrial Motion Corp.
	Net income	$	0.34	$	0.25	$	0.46	$	0.41
	Year ended December 31, 2013
		Fourth		Third		Second		First
		Quarter		Quarter		Quarter		Quarter
	Net Sales	$	180,530	$	175,443	$	181,095	$	185,150
	Gross Profit	51,805		53,658		54,419		55,499
	Net income attributable to Altra	7,205		10,501		10,689		11,880
	Industrial Motion Corp.
	Earnings per share — Basic
	Net income attributable to Altra Industrial Motion Corp.	$	0.27	$	0.39	$	0.4	$	0.44
	Earnings per share — Diluted
	Net income attributable to Altra Industrial Motion Corp.	$	0.27	$	0.39	$	0.4	$	0.44

Description_of_Business_and_Su3

Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 11, 2012	Dec. 31, 2011
	Reporting_Unit
	subsidiary
Organization And Nature Of Business [Line Items]
Anti-dilutive shares	2,571,130	3,137,351	3,094,706
Percentage of ownership acquired				85.00%
Number of entity subsidiaries excluded	1
Percentage of inventory LIFO	7.00%	7.50%
Impairment of long-lived assets	$0	$0
Company's reporting units	1
Net carrying value of debt issuance cost	3,200,000	4,100,000
Advertising costs	2,900,000	2,500,000	2,100,000
Impairment of goodwill	0	0			0
Tax benefit sustainable	greater than 50%
Convertible Notes [Member]
Organization And Nature Of Business [Line Items]
Estimated fair value of financial instruments	99,000,000	116,500,000
Carrying amount of financial instruments	85,000,000	85,000,000
Interest on notes	2.75%	2.75%
Minimum [Member]
Organization And Nature Of Business [Line Items]
Amortization straight-line basis	8 years
Royalty rate indication based on return as a percentage of revenue	1.00%
Maximum [Member]
Organization And Nature Of Business [Line Items]
Amortization straight-line basis	17 years
Royalty rate indication based on return as a percentage of revenue	1.25%
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Organization And Nature Of Business [Line Items]
Estimated fair value of interest rate swap	100,000	100,000
Money Market Funds [Member]
Organization And Nature Of Business [Line Items]
Cash and cash equivalents	300,000	16,600,000
Brand [Member]
Organization And Nature Of Business [Line Items]
Number of product lines	42
Production facilities in number of countries	12
Term Loan Facility [Member]
Organization And Nature Of Business [Line Items]
Estimated fair value of financial instruments	133,697,000
Revolving Credit Facility [Member]
Organization And Nature Of Business [Line Items]
Estimated fair value of financial instruments	$200,000,000
2004 Plan [Member]
Organization And Nature Of Business [Line Items]
Total number of shares of common stock available for delivery pursuant to the grant of awards	750,000

Description_of_Business_and_Su4

Description of Business and Summary of Significant Accounting Policies - Reconciliation of Basic to Diluted Net Income Per Share (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net income attributable to Altra Industrial Motion Corp.	$9,059	$12,797	$11,365	$7,205	$6,946	$10,501	$10,689	$11,880	$40,167	$40,275	$24,293
Weighted average shares, basic									26,713	26,766	26,656
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities									612	0	0
Incremental shares of unvested restricted common stock									78	75	100
Weighted average shares, diluted (in shares)									27,403	26,841	26,756
Earnings per share:
Basic net income attributable to Altra Industrial Motion Corp. (in usd per share)	$0.34	$0.48	$0.43	$0.27	$0.26	$0.39	$0.40	$0.44	$1.50	$1.50	$0.91
Diluted net income attributable to Altra Industrial Motion Corp. (in usd per share)	$0.34	$0.46	$0.41	$0.27	$0.25	$0.39	$0.40	$0.44	$1.47	$1.50	$0.91

Description_of_Business_and_Su5

Description of Business and Summary of Significant Accounting Policies - Depreciation of Property, Plant and Equipment, Including Capital Leases is Provided Using Straight-Line Method Over Estimated Useful Life of Asset (Detail)	12 Months Ended
	Dec. 31, 2014
Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Buildings and improvements/Machinery and equipment	15 years
Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Buildings and improvements/Machinery and equipment	45 years
Machinery and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Buildings and improvements/Machinery and equipment	2 years
Machinery and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Buildings and improvements/Machinery and equipment	15 years

Description_of_Business_and_Su6

Description of Business and Summary of Significant Accounting Policies - Changes in Accumulated Other Comprehensive Loss by Component (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Loss, Beginning Balance	($18,396)	($23,403)	($25,076)
Net current-period Other Comprehensive Income (Loss)	-23,019	5,007	1,673
Accumulated Other Comprehensive Loss, Ending Balance	-41,415	-18,396	-23,403
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Loss, Beginning Balance	135	0		0
Net current-period Other Comprehensive Income (Loss)	8	135
Accumulated Other Comprehensive Loss, Ending Balance	143	135		0
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Loss, Beginning Balance	-3,133	-4,607	-2,485
Net current-period Other Comprehensive Income (Loss)	-1,685	1,474	-2,122
Accumulated Other Comprehensive Loss, Ending Balance	-4,818	-3,133	-4,607
Cumulative Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Loss, Beginning Balance	-15,398	-18,796	-22,591
Net current-period Other Comprehensive Income (Loss)	-21,342	3,398	3,795
Accumulated Other Comprehensive Loss, Ending Balance	($36,740)	($15,398)	($18,796)

Acquisitions_Additional_Inform

Acquisitions - Additional Information (Detail)	12 Months Ended		0 Months Ended				12 Months Ended	0 Months Ended		12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Jul. 01, 2014	Jul. 01, 2014	Jul. 11, 2012	Dec. 31, 2014	Dec. 31, 2014	Dec. 17, 2013	Dec. 17, 2013	Dec. 31, 2014	Dec. 31, 2014
	USD ($)	USD ($)	Guardian [Member]	Guardian [Member]	Guardian [Member]	Guardian [Member]	Guardian [Member]	Svendborg [Member]	Svendborg [Member]	Svendborg [Member]	Svendborg [Member]
	Country		USD ($)	EUR (€)	USD ($)	USD ($)	Customer Relationships [Member]	USD ($)	EUR (€)	USD ($)	EUR (€)
Business Acquisition [Line Items]
Business acquisition cash consideration			$17,100,000	€ 17,100,000				$110,200,000	€ 80,100,000
Acquisition costs					200,000					2,500,000
Excess of purchase price over fair value of net assets acquired						2,200,000		17,986,000
Cash						2,000,000		7,500,000	5,400,000
Assets, Current	310,801,000	349,205,000				4,000,000
Assets, Noncurrent						9,200,000
Liabilities, Current	119,628,000	140,073,000				300,000
Useful lives of intangible assets							14 years
Escrow deposits established for transfer pricing claims								11,600,000	8,500,000
Estimated liability for transfer pricing claims by the company								8,100,000
transfer pricing claim										8,100,000	5,900,000
Business acquisition number of countries in which entity operates	7
Estimated receivables from transfer pricing claims by the company								$8,100,000

Acquisitions_Preliminary_Purch

Acquisitions - Preliminary Purchase Price Allocation as of Acquisition Date (Detail) (USD $)	Dec. 31, 2014	Dec. 17, 2013
In Thousands, unless otherwise specified
Guardian [Member]
Business Acquisition [Line Items]
Intangible assets		$8,100
Excess of purchase price over fair value of net assets acquired	2,200
Svendborg [Member]
Business Acquisition [Line Items]
Purchase price, excluding acquisition costs of approximately $2.5 million		102,096
Cash and cash equivalents		7,483
Trade receivables		20,860
Inventories		25,228
Prepaid and other		5,435
Property, plant and equipment		12,216
Other assets		1,133
Intangible assets		48,893
Total assets acquired		121,248
Accounts payable		4,833
Accrued expenses and other current liabilities		10,137
Taxes payable		10,254
Deferred tax liability		11,914
Total liabilities assumed		37,138
Net assets acquired		84,110
Excess of purchase price over fair value of net assets acquired		17,986
Scenario, Previously Reported [Member]
Business Acquisition [Line Items]
Purchase price, excluding acquisition costs of approximately $2.5 million		102,096
Cash and cash equivalents		7,483
Trade receivables		21,575
Inventories		25,452
Prepaid and other		5,511
Property, plant and equipment		12,216
Other assets		1,133
Intangible assets		48,893
Total assets acquired		122,263
Accounts payable		4,833
Accrued expenses and other current liabilities		9,620
Taxes payable		10,254
Deferred tax liability		11,483
Total liabilities assumed		36,190
Net assets acquired		86,073
Excess of purchase price over fair value of net assets acquired		16,023
Scenario, Adjustment [Member] | Svendborg [Member]
Business Acquisition [Line Items]
Purchase price, excluding acquisition costs of approximately $2.5 million		0
Cash and cash equivalents		0
Trade receivables		-715
Inventories		-224
Prepaid and other		-76
Property, plant and equipment		0
Other assets		0
Intangible assets		0
Total assets acquired		-1,015
Accounts payable		0
Accrued expenses and other current liabilities		517
Taxes payable		0
Deferred tax liability		431
Total liabilities assumed		948
Net assets acquired		-1,963
Excess of purchase price over fair value of net assets acquired		$1,963

Acquisitions_Amounts_Recorded_

Acquisitions - Amounts Recorded as Intangible Assets (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 17, 2013
Guardian [Member]
Intangible Asset Excluding Goodwill [Line Items]
Trade names and trademarks, not subject to amortization		$650
Total intangible assets		8,100
Svendborg [Member]
Intangible Asset Excluding Goodwill [Line Items]
Trade names and trademarks, not subject to amortization		8,500
Total intangible assets		48,893
Customer Relationships [Member] | Guardian [Member]
Intangible Asset Excluding Goodwill [Line Items]
Useful lives of intangible assets	14 years
Customer relationships, subject to amortization		7,450
Customer Relationships [Member] | Svendborg [Member]
Intangible Asset Excluding Goodwill [Line Items]
Customer relationships, subject to amortization		40,050
Patents [Member] | Svendborg [Member]
Intangible Asset Excluding Goodwill [Line Items]
Customer relationships, subject to amortization		$343

Acquisitions_Proforma_Amount_o

Acquisitions - Proforma Amount on Acquisition Occurred (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Combinations [Abstract]
Total revenues	$825,723	$813,477	$818,956
Net income attributable to Altra Industrial Motion Corp.	$42,632	$38,695	$22,373
Basic earnings per share:
Net income attributable to Altra Industrial Motion Corp. (in usd per share)	$1.60	$1.45	$0.84
Diluted earnings per share:
Net income attributable to Altra Industrial Motion Corp. (in usd per share)	$1.56	$1.44	$0.84

Inventories_Summary_of_Invento

Inventories - Summary of Inventories (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]
Raw materials	$36,814	$56,824
Work in process	13,641	18,432
Finished goods	82,281	68,409
Inventories, net	$132,736	$143,665

Inventories_Additional_Informa

Inventories - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Inventory [Line Items]
Portion of total inventory valued by LIFO method	7.00%	7.50%
Change in the inventory balance using FIFO method	$1.70	$1.60
Inventory Valuation by LIFO Method [Member]
Inventory [Line Items]
Portion of total inventory valued by LIFO method	7.00%
Inventory Valuation Provision [Member]
Inventory [Line Items]
Provision for valuation of sales component	$0.10	$0.70

Property_Plant_and_Equipment_S

Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$292,247	$281,074
Less-Accumulated depreciation	-135,881	-123,539
Property, plant and equipment, net	156,366	157,535
Depreciation expense	23,118	21,419	20,537
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	26,560	20,803
Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	44,791	53,078
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$220,896	$207,193

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Changes in Goodwill (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Gross goodwill balance as of January 1		$120,035
Accumulated impairment, January 1		-31,810
Adjustments related to the acquisition of Svendborg in 2013 and Lamiflex in 2012	4,143	16,023
Impact of changes in foreign currency and other	-6,395	91
Net goodwill balance December 31	102,087	104,339
Clutches and Brakes [Member]
Goodwill [Roll Forward]
Gross goodwill balance as of January 1		37,784
Accumulated impairment, January 1		-3,745
Adjustments related to the acquisition of Svendborg in 2013 and Lamiflex in 2012	1,963	16,023
Impact of changes in foreign currency and other	-4,741	418
Net goodwill balance December 31	47,702	50,480
Couplings [Member]
Goodwill [Roll Forward]
Gross goodwill balance as of January 1		36,138
Accumulated impairment, January 1		-14,982
Adjustments related to the acquisition of Svendborg in 2013 and Lamiflex in 2012	2,180	0
Impact of changes in foreign currency and other	-512	-414
Net goodwill balance December 31	22,410	20,742
Gearing and Power Transmission Components [Member] [Member]
Goodwill [Roll Forward]
Gross goodwill balance as of January 1		46,113
Accumulated impairment, January 1		-13,083
Adjustments related to the acquisition of Svendborg in 2013 and Lamiflex in 2012	0	0
Impact of changes in foreign currency and other	-1,142	87
Net goodwill balance December 31	$31,975	$33,117

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets - Intangibles and Related Accumulated Amortization (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]
Total intangible assets, Cost	$166,610	$167,436
Total intangible assets, Accumulated Amortization	55,880	48,668
Total intangible assets, net	110,730	118,768
Tradenames and Trademarks [Member]
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets not subject to amortization, Cost	41,257	42,605
Customer Relationships [Member]
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization, Cost	118,523	117,848
Total intangible assets, Accumulated Amortization	49,849	42,582
Finite-Lived Intangible Assets, Net	68,674	75,266
Product Technology and Patents [Member]
Schedule Of Finite And Indefinite Lived Intangible Assets [Line Items]
Intangible assets subject to amortization, Cost	6,830	6,983
Total intangible assets, Accumulated Amortization	6,031	6,086
Finite-Lived Intangible Assets, Net	$799	$897

Goodwill_and_Intangible_Assets4

Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill And Intangible Assets [Line Items]
Amortization expense	$9,019,000	$6,505,000	$6,839,000
Weighted average estimated useful life of intangible assets	11 years
Estimated Amortization Expense for Intangible Assets [Member]
Goodwill And Intangible Assets [Line Items]
Year 2014	8,200,000
Year 2015	8,200,000
Year 2016	8,200,000
Year 2017	8,200,000
Year 2018	8,200,000
Thereafter	$28,500,000
Minimum [Member]
Goodwill And Intangible Assets [Line Items]
Useful lives of intangible assets	8 years
Maximum [Member]
Goodwill And Intangible Assets [Line Items]
Useful lives of intangible assets	17 years

Warranty_Costs_Additional_Info

Warranty Costs - Additional Information (Detail)	12 Months Ended
	Dec. 31, 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 $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement in Extended Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$8,739	$5,625	$4,898
Accrued current period warranty costs	1,537	2,573	2,386
Acquired warranty reserves	0	3,420	0
Payments and adjustments	-2,484	-2,879	-1,659
Balance at end of period	$7,792	$8,739	$5,625

Income_Taxes_Income_Before_Inc

Income Taxes - Income Before Income Taxes by Domestic and Foreign Locations (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Domestic	$33,065	$37,640	$18,083
Foreign	30,053	21,696	16,276
Total	$63,118	$59,336	$34,359

Income_Taxes_Components_of_Pro

Income Taxes - Components of Provision (Benefit) for Income Taxes (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current:
Federal	$12,545	$8,917	$8,370
State	299	698	-3,597
Non-US	7,380	6,072	6,006
Current, total	20,224	15,687	10,779
Deferred:
Federal	2,673	3,533	-915
State	198	378	1,756
Non-US	-159	-447	-1,466
Deferred, total	2,712	3,464	-625
Provision for income taxes	$22,936	$19,151	$10,154

Income_Taxes_Reconciliation_fr

Income Taxes - Reconciliation from Tax at U.S. Federal Statutory Rate to Company's Provision (Benefit) for Income Taxes (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Tax at US federal income tax rate	$22,092	$20,767	$12,026
State taxes, net of federal income tax effect	495	905	67
Change in tax rate	11	-354	-267
Foreign reorganization	3,786	0	0
Foreign taxes	-1,978	-224	781
Adjustments to accrued income tax liabilities and uncertain tax positions	-287	-52	-1,289
Valuation allowance	612	120	506
Intercompany interest	-910	-986	-1,676
Tax credits and incentives	-666	-816	-291
Domestic manufacturing deduction	-1,201	-839	-566
Other	982	630	863
Provision for income taxes	$22,936	$19,151	$10,154

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of Gross Amount of Unrecognized Tax Benefits Excluding Accrued Interest and Penalties (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$627	$747	$3,523
Increases related to prior year tax positions	0	0	0
Decreases related to prior year tax positions	0	-33	0
Increases related to current year tax positions	0	0	0
Settlements	-176	0	-2,689
Lapse of statute of limitations	-17	-87	-87
Balance at end of period	$434	$627	$747

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Unrecognized Tax Benefits [Line Items]
Recognized tax benefit	$22,936,000	$19,151,000	$10,154,000
Accrued interest and penalties	100,000	100,000	200,000
Offset of accrued interest and penalties due to lapse of statute of limitations	300,000
Total gross amount of interest and penalties	200,000	400,000	400,000
Net operating loss	24,300,000
Federal and state tax credits	666,000	816,000	291,000
U.S. or additional non-U.S. taxes, undistributed earnings	70,800,000
Valuation allowance	5,974,000	5,577,000
Minimum [Member]
Unrecognized Tax Benefits [Line Items]
Net operating loss, expire year	2019
Maximum [Member]
Unrecognized Tax Benefits [Line Items]
Net operating loss, expire year	2032
New York [Member]
Unrecognized Tax Benefits [Line Items]
Recognized tax benefit			2,500,000
Non-U.S. [Member]
Unrecognized Tax Benefits [Line Items]
Net operating loss	21,800,000
Federal and State Tax Credits [Member]
Unrecognized Tax Benefits [Line Items]
Federal and state tax credits	$2,400,000
Federal and State Tax Credits [Member] | Minimum [Member]
Unrecognized Tax Benefits [Line Items]
Net operating loss, expire year	2015
Federal and State Tax Credits [Member] | Maximum [Member]
Unrecognized Tax Benefits [Line Items]
Net operating loss, expire year	2029

Income_Taxes_Significant_Compo

Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Deferred tax assets:
Post-retirement obligations	$1,363	$1,565
Tax credits	2,194	2,165
Expenses not currently deductible	11,457	11,788
Net operating loss carryover	5,901	6,376
Other	519	546
Total deferred tax assets	21,434	22,440
Valuation allowance for deferred tax assets	-5,974	-5,577
Net deferred tax assets	15,460	16,863
Deferred tax liabilities:
Property, plant and equipment	19,002	20,065
Intangible assets	22,735	25,090
Basis difference - convertible debt	11,875	11,064
Goodwill	4,967	3,813
Total deferred liabilities	58,579	60,032
Net deferred tax liabilities	$43,119	$43,169

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) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Employer contributions	$4,000	$3,700	$3,500
Amounts Recognized in the balance sheet consist of:
Total	-9,993	-8,025
Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Obligation at beginning of period	32,215	34,629
Partial settlement gain	-582	0
Service cost	243	248	179
Interest cost	1,353	1,250	1,381
Partial settlement payments	-2,080	0
Actuarial (gains) losses	5,978	-2,969
Foreign exchange effect	-909	343
Benefits paid	-1,357	-1,286
Obligation at end of period	34,861	32,215	34,629
Fair value of plan assets, beginning of period	24,190	20,100
Partial settlement payments	-2,080	0
Actual return on plan assets	3,668	182
Employer contributions	447	5,194
Benefits paid	-1,357	-1,286
Fair value of plan assets, end of period	24,868	24,190	20,100
Funded status	-9,993	-8,025
Amounts Recognized in the balance sheet consist of:
Non-current liabilities	-9,993	-8,025
Total	($9,993)	($8,025)

Pension_and_Other_Employee_Ben3

Pension and Other Employee Benefits - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Accumulated benefit obligation	$34,900,000	$32,200,000
Non-U.S. pension liabilities recognized	8,300,000	7,700,000
Accumulated other comprehensive loss	4,800,000	3,100,000
Accumulated other comprehensive loss, net of tax	1,700,000	1,100,000
Defined contribution plans, maximum employee contribution	75.00%
Percent of contribution made	6.00%
Contribution description	The Company makes matching contributions equal to half of the first six percent of salary contributed by each employee
Defined benefit plan, supplementary contributions by employer	4,000,000	3,700,000	3,500,000
U.S. Pension Plan 2013 [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Minimum cash contribution to pension plan	200,000
U.S. Pension Plan 2014 [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Minimum cash contribution to pension plan	0
U.S. Pension Plan 2015 [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Minimum cash contribution to pension plan	0
U.S. Pension Plan 2016 [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Minimum cash contribution to pension plan	0
U.S. Pension Plan 2017 [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Minimum cash contribution to pension plan	0
U.S. Pension Plan 2018 [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Minimum cash contribution to pension plan	$0

Pension_and_Other_Employee_Ben4

Pension and Other Employee Benefits - Discount Rate Used in Computation of Respective Benefit Obligations (Detail) (Pension Benefits [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate used in benefit obligation	3.70%	4.60%

Pension_and_Other_Employee_Ben5

Pension and Other Employee Benefits - Components of Net Periodic Benefit Cost (Detail) (Pension Benefits [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$243	$248	$179
Interest cost	1,353	1,250	1,381
Expected return on plan assets	-1,084	-1,080	-1,083
Non-cash impact of partial pension settlement	475	0	0
Amortization of actuarial losses	159	175	105
Net periodic benefit cost	$1,146	$593	$582

Pension_and_Other_Employee_Ben6

Pension and Other Employee Benefits - Economic Assumptions Used in Computation of Respective Net Periodic Benefit Cost (Detail) (Pension Benefits [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Economic Assumptions Used In Measuring Of Fair Value Securitized Loans [Line Items]
Discount rate	4.60%	3.75%	4.75%
Expected return on plan assets	4.60%	5.25%	6.25%

Pension_and_Other_Employee_Ben7

Pension and Other Employee Benefits - Schedule Fair Value of Pension Plan Assets (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Total fixed income	$24,326	$23,512
Total assets at fair value	24,868	24,190
U.S. Government [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Total fixed income	3,554	2,787
Investment Grade [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Total fixed income	17,682	17,091
High Yield [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Total fixed income	3,090	3,634
Other [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Total assets at fair value	286	338
Cash and Cash Equivalents [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Total assets at fair value	$256	$340

Pension_and_Other_Employee_Ben8

Pension and Other Employee Benefits - Schedule of Asset Allocations for Funded Retirement Plan (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Global Developed Equity [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Target, Minimum	0.00%
Target, Maximum	0.00%
Investment Grade Bonds [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Actual	86.00%	84.00%
Target, Minimum	70.00%
Target, Maximum	100.00%
High Yield Bonds [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Actual	13.00%	15.00%
Target, Minimum	0.00%
Target, Maximum	25.00%
Cash [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Actual	1.00%	1.00%
Target, Minimum	0.00%
Target, Maximum	5.00%
Emerging Market Debt [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Target, Minimum	0.00%
Target, Maximum	0.00%
Dynamic Asset Allocation/Alternatives [Member]
Defined Benefit Pension Plan With Accumulated Benefit Obligation In Excess Of Fair Value Of Plan Assets [Line Items]
Target, Minimum	0.00%
Target, Maximum	0.00%

Pension_and_Other_Employee_Ben9

Pension and Other Employee Benefits - Summary of Amounts of Expected Benefit Payments (Detail) (Pension Benefits [Member], USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Pension Benefits [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Maturity [Line Items]
2015	$1,287
2016	1,366
2017	1,409
2018	1,488
2019	1,564
Thereafter	$7,858

LongTerm_Debt_Outstanding_Debt

Long-Term Debt - Outstanding Debt Obligations (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Total debt	$268,508	$294,435
Less: debt discount, net of accretion	-12,756	-16,163
Total debt, net of unaccreted discount	255,752	278,272
Less current portion of long-term debt	-15,176	-16,924
Total long-term debt	240,576	261,348
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total debt	40,000	41,198
Convertible Notes [Member]
Debt Instrument [Line Items]
Total debt	85,000	85,000
Term Loan Facility [Member]
Debt Instrument [Line Items]
Total debt	133,697	163,245
Bank Loan [Member]
Debt Instrument [Line Items]
Total debt	3,647	0
Equipment Loan [Member]
Debt Instrument [Line Items]
Total debt	5,430	4,155
Mortgages [Member]
Debt Instrument [Line Items]
Total debt	258	659
Capital Leases [Member]
Debt Instrument [Line Items]
Total debt	$476	$178

LongTerm_Debt_Additional_Infor

Long-Term Debt - Additional Information (Detail)

12 Months Ended

12 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Nov. 20, 2012

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Sep. 01, 2011

Sep. 01, 2011

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

USD ($)

USD ($)

Initial Conversion Price [Member]

Term Loan [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Additional Term Loan [Member]

Additional Term Loan [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Term Loan Facility [Member]

Term Loan Facility [Member]

Revolving Credit Agreement [Member]

Revolving Credit Agreement [Member]

Convertible Debt [Member]

Convertible Debt [Member]

Convertible Notes [Member]

Convertible Notes [Member]

Convertible Notes [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Mortgages [Member]

Bank Loan [Member]

Bank Loan [Member]

Capital Leases [Member]

Capital Leases [Member]

Equipment and Working Capital Notes [Member]

Equipment and Working Capital Notes [Member]

Equipment and Working Capital Notes [Member]

Equipment and Working Capital Notes [Member]

USD ($)

USD ($)

USD ($)

USD ($)

EUR (€)

Eurodollar Loan [Member]

ABR Based Loans [Member]

USD ($)

Eurodollar Loan [Member]

ABR Based Loans [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

EUR (€)

USD ($)

EUR (€)

USD ($)

EUR (€)

USD ($)

USD ($)

USD ($)

CNY

Minimum [Member]

Maximum [Member]

Debt Instrument [Line Items]

Availability under credit facility agreement

$94,375,000

€ 50,000,000

$100,000,000

$200,000,000

$200,000,000

Aggregate additional term loans

150,000,000

Credit facility maturity date

11/20/17

12/6/18

Debt instrument, maturity date

20-Nov-17

6-Dec-18

1-Mar-31

Applicable margins for loans

1.38%

0.38%

1.88%

0.88%

Outstanding on Revolving Credit Facility

40,000,000

41,200,000

Letters of credit outstanding

11,000,000

9,800,000

Amount available under credit facility

149,000,000

Percentage of capital stock not included in collateral

65.00%

Coupon interest rate

2.75%

2.75%

Proceeds from the offering

81,300,000

Adjustment of shares (in shares)

36.0985

Principal amount of notes

1,000

Conversion price per share (in usd per share)

$26.71

$27.70

Percentage of sale price of common stock

130.00%

Conversion price (in usd per share)

$26.71

Consecutive trading days

30 days

20 days

30 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

85,000,000

85,000,000

500,000

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

3,200,000

4,100,000

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%

Available to borrow loan amount

6,300,000

38,500,000

Interest rate

5.75%

5.75%

2.50%

2.50%

5.40%

8.00%

Bank loan remaining amount

3,600,000

3,000,000

Line of credit outstanding loan amount

5,400,000

33,300,000

Description about maturity date of debt instrument

The note is due in installments from 2014 through 2016

The note is due in installments from 2014 through 2016

Mortgage remaining principal balance

300,000

200,000

700,000

500,000

7,900,000

6,000,000

Borrowings under overdraft agreements

$0

$0

LongTerm_Debt_Carrying_Amount_

Long-Term Debt - Carrying Amount of Debt (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Carrying value of debt	$240,576	$261,348
Convertible Debt [Member]
Debt Instrument [Line Items]
Principal amount of debt	85,000
Unamortized discount	12,756
Carrying value of debt	$72,244

LongTerm_Debt_Interest_Expense

Long-Term Debt - Interest Expense Associated with Convertible Notes (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Disclosure [Abstract]
Contractual coupon rate of interest	$2,338	$2,338	$2,338
Accretion of Convertible Notes discount and amortization of deferred financing costs	3,760	3,494	3,239
Interest expense for the Convertible Notes	$6,098	$5,832	$5,577

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	31-May-14	Dec. 20, 2006
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized	90,000,000	90,000,000	90,000,000
Common stock, shares outstanding	26,819,795	26,353,755	26,819,795
Preferred Stock, shares authorized	10,000,000	10,000,000	10,000,000			10,000,000
Preferred Stock, shares issued	0	0	0
Preferred Stock, shares outstanding	0	0	0
Compensation expense		$3,400,000	$3,200,000	$2,700,000
Compensation expense, net of tax		2,900,000	2,900,000	1,800,000
Weighted average remaining period		2 years
Unrecognized compensation cost		3,700,000
Stock price		$28.39
Fair market value of the shares		3,800,000	2,400,000	3,200,000
Cash dividend declared (in usd per share)	$0.10	$0.46	$0.38	$0.16
Dividend paid	2,696,000	0	2,696,000	0
Stock Repurchase Program, Authorized Amount					50,000,000
Stock Repurchased and Retired During Period, Shares		545,154
Common stock purchase price (in usd per share)		$32.32
Stock Repurchase Program, Remaining Authorized Repurchase Amount		32,300,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of stock awards		$4,500,000
2004 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares left from termination of 2004 Plan		750,000
2004 Plan [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding at termination		750,576
Shares left from termination of 2004 Plan		750,000

Stockholders_Equity_Schedule_o

Stockholders' Equity - Schedule of Activity of Company's Restricted Stock Grants (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Restricted shares unvested, beginning balance	149,635
Shares granted	136,340
Shares for which restrictions lapsed	-126,797
Restricted shares unvested, ending balance	159,178
Weighted-Average Grant Date Fair Value, beginning balance	$23.02
Weighted-Average Grant Date Fair Value, Shares granted	$33.52
Weighted-Average Grant Date Fair Value, Shares for which restrictions lapsed	$29.58
Weighted-Average Grant Date Fair Value, ending balance	$28.53

Stockholders_Equity_Share_Repu

Stockholders' Equity Share Repurchases (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	31-May-14
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount		$50
Stock Repurchased and Retired During Period, Shares	545,154
Common stock purchase price (in usd per share)	$32.32
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$32.30
Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchased and Retired During Period, Shares	545,154

Stockholders_Equity_Dividends_

Stockholders' Equity Dividends (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Equity [Abstract]
Cash dividend declared (in usd per share)	$0.10	$0.46	$0.38	$0.16
Dividend accrued	$2,696	$0	$2,696	$0

Concentrations_Additional_Info

Concentrations - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Customer	Customer	Customer
Concentration Risk [Line Items]
Sales contract payments due period	30 days
Percentage of labor force is represented by collective bargaining agreements	23.00%
Number of collective bargaining agreements	4
Collective Bargaining, July 2014 [Member]
Concentration Risk [Line Items]
Collective bargaining agreements, expire date	1-Jul-15
Collective Bargaining, October 2014 [Member]
Concentration Risk [Line Items]
Collective bargaining agreements, expire date	1-Oct-16
Collective Bargaining, June 2014 [Member]
Concentration Risk [Line Items]
Collective bargaining agreements, expire date	1-Jun-17
Collective Bargaining, October 2016 [Member]
Concentration Risk [Line Items]
Collective bargaining agreements, expire date	1-Feb-18
Sales [Member]
Concentration Risk [Line Items]
Maximum revenue percentage from any one customer	10.00%	10.00%	10.00%
Number of customers representing over 10% of total sales	0	0	0
The Americas (Primarily U.S.) [Member]
Concentration Risk [Line Items]
Percentage of labor force is represented by collective bargaining agreements	15.00%
Europe [Member]
Concentration Risk [Line Items]
Percentage of labor force is represented by collective bargaining agreements	56.00%

Restructuring_Asset_Impairment2

Restructuring, Asset Impairment, and Transition Expenses - Summary of Total Restructuring Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Expenses
Restructuring costs	$1,767	$1,111	$3,196
Clutches and Brakes [Member]
Expenses
Restructuring costs	916	373	393
Couplings [Member]
Expenses
Restructuring costs	142	234	74
Gearing and Power Transmission Components [Member] [Member]
Expenses
Restructuring costs	603	504	2,729
Corporate [Member] [Member]
Expenses
Restructuring costs	$106	$0	$0

Restructuring_Asset_Impairment3

Restructuring, Asset Impairment, and Transition Expenses - Reconciliation of Accrued Restructuring Costs (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restructuring Reserve [Roll Forward]
Beginning Balance	$429	$2,815	$90
Restructuring costs	1,767	1,111	3,196
Cash payments	-1,807	-3,497	-471
Ending Balance	$389	$429	$2,815

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Apr. 30, 2013
Debt Instrument [Line Items]
Ineffectiveness associated with the swap	$0
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Outstanding borrowings	$82,500,000	$82,500,000
Fixed Rate	0.63%	0.63%

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Summary of Swap Recognized in Other Non-Current Assets and in Other Comprehensive Income (Loss) (Detail) (Interest Rate Swap [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Apr. 30, 2013
Interest Rate Swap [Member]
Derivative [Line Items]
Effective Date	30-Apr-13
Notional Amount	$82,500		$82,500
Fixed Rate	0.63%		0.63%
Maturity	30-Nov-16
Fair Value	$143	$135

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014
	USD ($)	USD ($)	USD ($)	Maximum [Member]	Purchase Commitment [Member]	Purchase Commitment [Member]
					Inventory [Member]	Inventory [Member]
					USD ($)	EUR (€)
Schedule Of Commitments And Contingencies [Line Items]
Term of lease				10 years
Net rent expense under operating leases	$8.80	$8.80	$7.80
Minimum purchase contracts					$4.40	€ 3.60

Commitments_and_Contingencies_2

Commitments and Contingencies - Future Minimum Rent Obligations under Non-Cancelable Operating and Capital Leases (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Operating Leases
2015	$6,891
2016	5,816
2017	4,546
2018	2,538
2019	1,873
Thereafter	6,951
Total lease obligations	28,615
Capital Leases
2015	115
2016	115
2017	115
2018	115
2019	38
Thereafter	0
Total lease obligations	498
Less amounts representing interest	-22
Present value of minimum capital lease obligations	$476

Segment_and_Geographic_Informa2

Segment and Geographic Information - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
	Segment	Segment
Segment Reporting [Abstract]
Number of reportable segments	3	1

Segment_and_Geographic_Informa3

Segment and Geographic Information - Reconciliation of Segment Results to Consolidated Results (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Net sales	$191,961	$215,198	$210,138	$180,530	$202,520	$175,443	$181,095	$185,150	$819,817	$722,218	$731,990
Operating Income (Loss)									75,109	71,579	76,851
Restructuring									-1,767	-1,111	-3,196
Interest expense, net									11,994	10,586	40,790
Other Nonoperating Income (Expense)									-3	1,657	1,702
Total other non-operating expense (income), net									11,991	12,243	42,492
Total									63,118	59,336	34,359
Provision for income taxes									22,936	19,151	10,154
Net income									40,182	40,185	24,205
Depreciation and amortization									32,137	27,924	27,376
Purchase of Property, plant and equipment									28,050	27,823	31,346
Total assets	684,563			735,676					684,563	735,676	663,039
Clutches and Brakes [Member]
Segment Reporting Information [Line Items]
Net sales									426,293	336,616	334,901
Operating Income (Loss)									53,386	48,150	50,570
Restructuring									-916	-373	-393
Depreciation and amortization									12,936	9,203	8,847
Purchase of Property, plant and equipment									8,865	6,382	8,386
Total assets	334,371			364,826					334,371	364,826	244,255
Couplings [Member]
Segment Reporting Information [Line Items]
Net sales									134,464	125,169	128,705
Operating Income (Loss)									16,091	15,021	18,146
Restructuring									-142	-234	-74
Depreciation and amortization									5,655	5,402	5,016
Purchase of Property, plant and equipment									3,384	3,270	10,031
Total assets	117,805			109,279					117,805	109,279	112,910
Gearing and Power Transmission Components [Member] [Member]
Segment Reporting Information [Line Items]
Net sales									264,514	265,154	274,004
Operating Income (Loss)									24,534	23,881	22,421
Restructuring									-603	-504	-2,729
Depreciation and amortization									11,061	11,126	11,891
Purchase of Property, plant and equipment									13,413	15,001	6,767
Total assets	190,771			198,715					190,771	198,715	202,543
IntersegmentElim [Member]
Segment Reporting Information [Line Items]
Net sales									-5,454	-4,721	-5,620
Corporate [Member] [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)									-17,135	-14,362	-11,090
Restructuring									-106	0	0
Depreciation and amortization									2,485	2,193	1,622
Purchase of Property, plant and equipment									2,388	3,170	6,162
Total assets	$41,616			$62,856					$41,616	$62,856	$103,331

Segment_and_Geographic_Informa4

Segment and Geographic Information - Geographical Information (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Geographic Information
Net Sales	$191,961	$215,198	$210,138	$180,530	$202,520	$175,443	$181,095	$185,150	$819,817	$722,218	$731,990
Property, plant and equipment, net	156,366			157,535					156,366	157,535
North America [Member]
Geographic Information
Net Sales									488,523	454,115	469,554
Property, plant and equipment, net	90,279			87,573					90,279	87,573
Europe [Member]
Geographic Information
Net Sales									255,049	216,636	216,485
Property, plant and equipment, net	51,708			54,533					51,708	54,533
Asia and the Rest of the World [Member]
Geographic Information
Net Sales									76,245	51,467	45,951
Property, plant and equipment, net	$14,379			$15,429					$14,379	$15,429

Unaudited_Quarterly_Results_of2

Unaudited Quarterly Results of Operations - Schedule of Quarterly Results of Operations (Detail) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 28, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Net Sales	$191,961	$215,198	$210,138	$180,530	$202,520	$175,443	$181,095	$185,150	$819,817	$722,218	$731,990
Gross Profit	58,270	66,470	61,796	51,805	62,333	53,658	54,419	55,499	248,869	215,381	218,548
Net income attributable to Altra Industrial Motion Corp.	$9,059	$12,797	$11,365	$7,205	$6,946	$10,501	$10,689	$11,880	$40,167	$40,275	$24,293
Basic net income attributable to Altra Industrial Motion Corp. (in usd per share)	$0.34	$0.48	$0.43	$0.27	$0.26	$0.39	$0.40	$0.44	$1.50	$1.50	$0.91
Diluted net income attributable to Altra Industrial Motion Corp. (in usd per share)	$0.34	$0.46	$0.41	$0.27	$0.25	$0.39	$0.40	$0.44	$1.47	$1.50	$0.91

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended			3 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2015	Feb. 28, 2015
Subsequent Event [Line Items]
Cash dividend declared (in usd per share)	$0.10	$0.46	$0.38	$0.16
Subsequent Event [Member]
Subsequent Event [Line Items]
Cash dividend declared (in usd per share)					$0.12
Equity Incentive Plan [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Restricted common stock shares being approved						111,437

Schedule_II_Valuation_and_Qual1

Schedule II - Valuation and Qualifying Accounts (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reserve for Uncollectible Accounts:
Balance at Beginning of Period	$2,245	$2,560	$1,092
Additions	417	733	1,675
Deductions	-360	-1,048	-207
Balance at End of Period	$2,302	$2,245	$2,560