Long-Term Debt	9 Months Ended
Long-Term Debt	Sep. 30, 2023
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt Senior Secured Credit Facilities On December 17, 2021, we entered into a Third Amended and Restated Credit Agreement (the “Amended Credit Agreement”) among the Company and our subsidiary, EnPro Holdings Inc. ("EnPro Holdings"), as borrowers, certain foreign subsidiaries of the Company from time to time party thereto, as designated borrowers, the guarantors party thereto, the lenders party thereto and Bank of America, N.A., as Administrative Agent, Swing Line Lender and L/C Issuer. The Amended Credit Agreement provides for credit facilities in the initial aggregate principal amount of $1,007.5 million, consisting of a five-year, senior secured revolving credit facility of $400.0 million (the “Revolving Credit Facility”), a $142.5 million senior secured term loan facility in replacement of our existing senior secured term loan facility, maturing September 25, 2024 (the “Term Loan A-1 Facility”), a five-year, senior secured term loan facility of $315.0 million (the “Term Loan A-2 Facility”) and a 364-day, senior secured term loan facility of $150.0 million (the “364-Day Facility” and together with the Revolving Credit Facility, the Term Loan A-1 Facility and the Term Loan A-2 Facility, the “Facilities”). The Amended Credit Agreement also provides that we may seek incremental term loans and/or additional revolving credit commitments in an amount equal to the greater of $275.0 million and 100% of consolidated EBITDA for the most recently ended four-quarter period for which we have reported financial results, plus additional amounts based on a consolidated senior secured leverage ratio. The Amended Credit Agreement became effective on December 17, 2021. Borrowings under the 364-Day Facility bore interest at an annual rate of LIBOR plus 1.50% or base rate plus 0.50%. Initially, borrowings under the Facilities (other than the 364-Day Facility) bore interest at an annual rate of LIBOR plus 1.75% or base rate plus 0.75%, although these interest rates were subject to incremental increase or decrease based on a consolidated total net leverage ratio. On November 8, 2022, we entered into a First Amendment to the Amended Credit Agreement, which replaced the LIBOR-based interest rate option with an option based on Term SOFR ("Secured Overnight Financing Rate") plus (i) a credit spread adjustment of 0.10% and (ii) 1.75%, again subject to incremental increase or decrease based on a consolidated total net leverage ratio. In addition, a commitment fee accrues with respect to the unused amount of the Revolving Credit Facility at an annual rate of 0.225%, which rate is also subject to incremental increase or decrease based on a consolidated total net leverage ratio. The Term Loan A-1 Facility amortized on a quarterly basis in an annual amount equal to 2.50% of the original principal amount of the Term Loan A-1 Facility ($150.0 million) in year one after the closing, 5.00% of such original principal amount in year two and 1.25% of such original principal amount in each of the first three quarters of year three, with the remaining outstanding principal amount payable at maturity. The Term Loan A-2 Facility amortizes on a quarterly basis in an annual amount equal to 2.5% of the original principal amount of the Term Loan A-2 Facility in each of years one through three, 5.0% of such original principal amount in year four and 1.25% of such original principal amount in each of the first three quarters of year five, with the remaining outstanding principal amount payable at maturity. The 364-Day Facility did not amortize and was repaid in full in the third quarter of 2022. The Facilities are subject to prepayment with the net cash proceeds of certain asset sales, casualty or condemnation events and non-permitted debt issuances. The Company and EnPro Holdings are the permitted borrowers under the Facilities. The Company may also from time to time designate any of its wholly owned foreign subsidiaries as a borrower under the Revolving Credit Facility. Each of the Company’s domestic subsidiaries (other than any subsidiaries that may be designated as “unrestricted” by the Company from time to time, and inactive subsidiaries) is required to guarantee the obligations of the borrowers under the Facilities, and each of the Company’s existing domestic subsidiaries (other than inactive subsidiaries) has entered into the Amended Credit Agreement to provide such a guarantee. Borrowings under the Facilities are secured by a first-priority pledge of certain assets. The Amended Credit Agreement contains certain financial covenants and required financial ratios including a maximum consolidated total net leverage and a minimum consolidated interest coverage as defined in the Amended Credit Agreement. We were in compliance with all covenants of the Amended Credit Agreement as of September 30, 2023. On July 21, 2023, we entered into a waiver agreement under the Amended Credit Agreement that waived the requirement to prepay the Facilities with remaining excess net cash proceeds related to the sale of GGB and GPT that had not been reinvested in operating assets within 365 days from the date of the sale. In conjunction with this waiver, on July 26, 2023, EnPro voluntarily prepaid all outstanding borrowings and accrued and unpaid interest under the Term Loan A-1 Facility (a remaining principal balance of $133.1 million and accrued interest of $0.6 million). The indenture governing the Senior Notes requires us to offer to repurchase the Senior Notes at a price equal to 100.0% of the principal amount thereof plus accrued and unpaid interest, in the event that the net cash proceeds of certain asset sales are not reinvested in acquisitions, capital expenditures, or used to repay or otherwise reduce specified indebtedness within a specified period, to the extent the remaining net proceeds exceed a specified amount. After taking into account the repayment of borrowings under the Term Loan A-1 Facility noted above, forecasted capital expenditures, and other applicable expenditures, we expect to meet all reinvestment requirements under the indenture related to the excess net cash proceeds from the sales of GGB and GPT. The borrowing availability under our Revolving Credit Facility at September 30, 2023 was $390.0 million after giving consideration to $10.0 million of outstanding letters of credit. The balance of borrowings outstanding under the Term Loan A-2 Facility at September 30, 2023 was $301.2 million. Senior Notes On October 17, 2018, we completed the offering of $350.0 million aggregate principal amount of 5.75% Senior Notes due 2026 (the "Senior Notes"). The Senior Notes were issued to investors at 100% of the principal amount thereof. The Senior Notes are unsecured, unsubordinated obligations of EnPro and mature on October 15, 2026. Interest on the Senior Notes accrues at a rate of 5.75% per annum and is payable semi-annually in cash in arrears on April 15 and October 15 of each year. The Senior Notes are required to be guaranteed on a senior unsecured basis by each of EnPro’s existing and future direct and indirect domestic subsidiaries that is a borrower under, or guarantees, our indebtedness under the Revolving Credit Facility or guarantees any other Capital Markets Indebtedness (as defined in the indenture governing the Senior Notes) of EnPro or any of the guarantors. We may, on any one or more occasions, redeem all or a part of the Senior Notes at specified redemption prices plus accrued and unpaid interest. The indenture governing the Senior Notes includes covenants that restrict our ability to engage in certain activities, including incurring additional indebtedness, paying dividends and repurchasing shares of our common stock, subject in each case to specified exceptions and qualifications set forth in the indenture. The indenture further requires us to offer to repurchase the Senior Notes at a price equal to 100.0% of the principal amount thereof plus accrued and unpaid interest, in the event that the net cash proceeds of certain asset sales are not reinvested in acquisitions, capital expenditures, or used to repay or otherwise reduce specified indebtedness within a specified period, to the extent the remaining net proceeds exceed a specified amount. This requirement applies to the net cash proceeds received in the divestitures of GGB and GPT and could require us to make such an offer to repurchase the Senior Notes in the first quarter of 2024 to the extent we do not sufficiently invest in acquisitions, assets, property or capital expenditures or repay or otherwise reduce specified indebtedness by then. We were in compliance with all of the covenants under the indenture governing the Senior Notes as of September 30, 2023.