Derivative Financial Instruments	3 Months Ended
Mar. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	16. Derivative Financial Instruments The Company may manage changes in market conditions related to interest on debt obligations and foreign currency exposures by entering into derivative instruments, including interest rate and foreign currency swap agreements. All derivative instruments are recognized as either assets or liabilities on the balance sheet at fair value at the end of each period. The Company determines the fair value of financial instruments using quoted market prices whenever available. When quoted market prices are not available for various types of financial instruments (such as forwards, options and swaps), the Company uses standard models with market-based inputs, which take into account the present value of estimated future cash flows and the ability of Altra or the financial counterparty to perform. For cross-currency interest rate swaps, the significant inputs are interest rate curves for discounting future cash flows, and exchange rate curves of the foreign currency for translating future cash flows. For interest rate swaps, the significant inputs to these models are interest rate curves for discounting future cash flows that are adjusted for credit risk. Both cross-currency interest rate swaps and interest rate swaps are Level 2 investments. Refer to Note 6 for a description of the fair value levels. For designated hedging relationships, the Company formally documents the hedging relationship consistent with the requirements of ASC 815, Derivatives. Cross-Currency Interest Rate Swaps In December 2018, the Company entered into cross-currency swap agreements to hedge its net investment in Euro-denominated assets against future volatility in the exchange rate between the U.S. dollar and the Euro. By doing so, the Company synthetically converted a portion of its U.S. dollar-based long-term debt into Euro-denominated long-term debt. At inception, the cross-currency swaps were designated as net investment hedges. For net investment hedges, changes in the fair value of the effective portion of the derivatives’ gains or losses are reported as foreign currency translation gains or losses in accumulated other comprehensive income (loss) (“AOCIL”). The gains or losses on derivative instruments reported in AOCIL are reclassified to earnings in the period in which earnings are affected by the underlying item, such as a disposal or substantial liquidations of the entities being hedged. During the first quarter of 2020, the Company terminated the cross-currency interest rate swaps. The Company received the cash value of the cross-currency interest rate swaps of approximately $56.2 million upon termination. In addition, the Company paid the interest owed and received the interest due, resulting in the recognition of approximately $3.3 million in net interest income, and paid termination fees of approximately $0.9 million. At March 31, 2022 and March 31, 2021, the Company had a gain in AOCIL of approximately $44.8 million, net of $11.4 million of tax. That balance will remain in AOCIL until the period in which earnings are affected by the underlying item, such as a disposal or substantial liquidations of the entities being hedged. Interest Rate Swaps In January 2017, the Company entered into an interest rate swap agreement to fix the variable interest rate payable on a portion of its outstanding borrowings. This interest rate swap matured on January 31, 2020. Additionally, in December 2018, the Company entered into an interest rate swap agreement designed to manage the cash flow risk caused by interest rate changes on the forecasted interest payments expected to occur related to a portion of its outstanding borrowings under the 2018 Credit Agreement. The interest rate swap agreement was designed to manage exposure to interest rates on the Company’s variable rate indebtedness and was recognized on the balance sheet at fair value. The Company designated this interest rate swap agreement as a cash flow hedge and changes in the fair value of the swap were recognized in other comprehensive income until the hedged items were recognized in earnings. During 2020, the Company terminated the interest rate swap agreement. The Company paid the cash value of the interest rate swaps of approximately $34.7 million upon termination. In addition, the Company paid the interest owed and received the interest due, resulting in the recognition of approximately $0.1 million in net interest expense, and paid termination fees of approximately $0.1 million. In November 2021, the Company terminated the 2018 Credit Agreement. As a result of the decision to terminate the 2018 Credit Agreement, the remaining balance of the unrealized loss in AOCIL was immediately reclassified to “Interest expense, net” in the accompanying condensed consolidated statements of operations. The Company reclassified $2.4 million, net of $0.7 million of tax benefit, of non-cash interest expense from AOCIL to earnings for the quarter ended March 31, 2021.

Derivative Financial Instruments

3 Months Ended

Mar. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

16. Derivative Financial Instruments

The Company may manage changes in market conditions related to interest on debt obligations and foreign currency exposures by entering into derivative instruments, including interest rate and foreign currency swap agreements. All derivative instruments are recognized as either assets or liabilities on the balance sheet at fair value at the end of each period. The Company determines the fair value of financial instruments using quoted market prices whenever available. When quoted market prices are not available for various types of financial instruments (such as forwards, options and swaps), the Company uses standard models with market-based inputs, which take into account the present value of estimated future cash flows and the ability of Altra or the financial counterparty to perform. For cross-currency interest rate swaps, the significant inputs are interest rate curves for discounting future cash flows, and exchange rate curves of the foreign currency for translating future cash flows. For interest rate swaps, the significant inputs to these models are interest rate curves for discounting future cash flows that are adjusted for credit risk. Both cross-currency interest rate swaps and interest rate swaps are Level 2 investments. Refer to Note 6 for a description of the fair value levels. For designated hedging relationships, the Company formally documents the hedging relationship consistent with the requirements of ASC 815, Derivatives.

Cross-Currency Interest Rate Swaps

In December 2018, the Company entered into cross-currency swap agreements to hedge its net investment in Euro-denominated assets against future volatility in the exchange rate between the U.S. dollar and the Euro. By doing so, the Company synthetically converted a portion of its U.S. dollar-based long-term debt into Euro-denominated long-term debt. At inception, the cross-currency swaps were designated as net investment hedges.

For net investment hedges, changes in the fair value of the effective portion of the derivatives’ gains or losses are reported as foreign currency translation gains or losses in accumulated other comprehensive income (loss) (“AOCIL”). The gains or losses on derivative instruments reported in AOCIL are reclassified to earnings in the period in which earnings are affected by the underlying item, such as a disposal or substantial liquidations of the entities being hedged. During the first quarter of 2020, the Company terminated the cross-currency interest rate swaps. The Company received the cash value of the cross-currency interest rate swaps of approximately $56.2 million upon termination. In addition, the Company paid the interest owed and received the interest due, resulting in the recognition of approximately $3.3 million in net interest income, and paid termination fees of approximately $0.9 million. At March 31, 2022 and March 31, 2021, the Company had a gain in AOCIL of approximately $44.8 million, net of $11.4 million of tax. That balance will remain in AOCIL until the period in which earnings are affected by the underlying item, such as a disposal or substantial liquidations of the entities being hedged.

Interest Rate Swaps

In January 2017, the Company entered into an interest rate swap agreement to fix the variable interest rate payable on a portion of its outstanding borrowings. This interest rate swap matured on January 31, 2020. Additionally, in December 2018, the Company entered into an interest rate swap agreement designed to manage the cash flow risk caused by interest rate changes on the forecasted interest payments expected to occur related to a portion of its outstanding borrowings under the 2018 Credit Agreement.

The interest rate swap agreement was designed to manage exposure to interest rates on the Company’s variable rate indebtedness and was recognized on the balance sheet at fair value. The Company designated this interest rate swap agreement as a cash flow hedge and changes in the fair value of the swap were recognized in other comprehensive income until the hedged items were recognized in earnings.

During 2020, the Company terminated the interest rate swap agreement. The Company paid the cash value of the interest rate swaps of approximately $34.7 million upon termination. In addition, the Company paid the interest owed and received the interest due, resulting in the recognition of approximately $0.1 million in net interest expense, and paid termination fees of approximately $0.1 million. In November 2021, the Company terminated the 2018 Credit Agreement. As a result of the decision to terminate the 2018 Credit Agreement, the remaining balance of the unrealized loss in AOCIL was immediately reclassified to “Interest expense, net” in the accompanying condensed consolidated statements of operations. The Company reclassified $2.4 million, net of $0.7 million of tax benefit, of non-cash interest expense from AOCIL to earnings for the quarter ended March 31, 2021.