Condensed consolidated interim financial statements Condensed consolidaed interim financial statements (Policies)	9 Months Ended
Sep. 30, 2023
Accounting Policies [Abstract]
Condensed consolidated interim financial statements	Condensed consolidated interim financial statementsThe unaudited condensed consolidated interim financial statements included in this report are prepared by the Company. In the opinion of management, all adjustments necessary for a fair presentation of the results of operations are reflected in these condensed consolidated interim financial statements. All significant intercompany accounts and transactions have been eliminated. The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of revenues, expenses, assets, liabilities, contingencies and noncontrolling interests subject to put provisions. The most significant estimates and assumptions underlying these financial statements and accompanying notes generally involve revenue recognition and accounts receivable, certain fair value estimates, accounting for income taxes and loss contingencies. The results of operations reflected in these interim financial statements may not necessarily be indicative of annual operating results. These condensed consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 (2022 10-K). Prior period classifications conform to the current period presentation. The Company has evaluated subsequent events through the date these condensed consolidated interim financial statements were issued and has included all necessary adjustments and disclosures.
Revenue	There are significant uncertainties associated with estimating revenue, many of which take several years to resolve. These estimates are subject to ongoing insurance coverage changes, geographic coverage differences, differing interpretations of contract coverage and other payor issues, as well as patient issues, including determination of applicable primary and secondary coverage, changes in patient insurance coverage and coordination of benefits. As these estimates are refined over time, both positive and negative adjustments to revenue are recognized in the current period. Dialysis patient service revenues. Revenues are recognized based on the Company’s estimate of the transaction price the Company expects to collect as a result of satisfying its performance obligations. Dialysis patient service revenues are recognized in the period services are provided based on these estimates. Revenues consist primarily of payments from government and commercial health plans for dialysis services provided to patients. Other revenues. Other revenues consist of revenues earned by the Company's non-dialysis ancillary services as well as fees for management and administrative services to outpatient dialysis businesses that the Company does not consolidate. Other revenues are estimated in the period services are provided. The Company's integrated kidney care (IKC) revenues include revenues earned under risk-based arrangements, including value-based care (VBC) arrangements. Under its VBC arrangements, the Company assumes full or shared financial risk for the total medical cost of care for patients below or above a benchmark. The benchmarks against which the Company incurs profit or loss on these contracts are typically based on the underlying premiums paid to the insuring entity (the Company's counterparty), with adjustments where applicable, or on trended or adjusted medical cost targets.
Earnings Per Share	Basic earnings per share is calculated by dividing net income attributable to the Company by the weighted average number of common shares outstanding. Weighted average common shares outstanding include restricted stock unit awards that are no longer subject to forfeiture because the recipients have satisfied either the explicit vesting terms or retirement eligibility requirements. Diluted earnings per share includes the dilutive effect of outstanding stock-settled stock appreciation rights and unvested stock units as computed under the treasury stock method.
Short-term and Long-term Investments	Debt securities. The Company's short-term debt investments are principally bank certificates of deposit with contractual maturities longer than three months but shorter than one year. The Company's long-term debt investments are bank time deposits with contractual maturities longer than one year. These debt securities are accounted for as held-to-maturity and recorded at amortized cost, which approximated their fair values at September 30, 2023 and December 31, 2022. Equity securities. The Company holds certain equity investments that have readily determinable fair values from public markets. The Company's remaining short-term and long-term equity investments are held within a trust to fund existing obligations associated with the Company’s non-qualified deferred compensation plans.
Long-term debt	These cap agreements are designated as cash flow hedges and, as a result, changes in their fair values are reported in other comprehensive income. The original premiums paid for the caps are amortized to debt expense on a straight-line basis over the term of each cap agreement starting from its effective date. These cap agreements do not contain credit risk-contingent features. In the second and third quarters of 2023 the Company entered into several forward interest rate cap agreements, described below, that have the economic effect of capping the Company's exposure to SOFR variable interest rate changes on specific portions of the Company's floating rate debt (2023 cap agreements). These 2023 cap agreements are designated as cash flow hedges and, as a result, changes in their fair values will be reported in other comprehensive income. These 2023 cap agreements, do not contain credit-risk contingent features, and become effective and expire as described in the table below. Certain of these 2023 cap agreements have notional amounts that amortize downward over time. On October 18, 2023, the Company entered into several forward interest rate cap agreements with an aggregate notional amount of $500,000 that become effective on June 28, 2024 and expire on December 31, 2026, and a forward interest rate cap agreement with an aggregate notional amount of $250,000 that becomes effective on December 31, 2024 and expires on December 31, 2025 (together, the October 2023 cap agreements). These October 2023 cap agreements have the economic effect of capping the Company's exposure to SOFR variable interest rate changes on specific portions of the Company's floating rate debt and do not contain credit-risk contingent features. Additionally, the October 2023 cap agreements are designated as cash flow hedges and, as a result, changes in their fair values will be reported in other comprehensive income. Finally, during and as of the end of the second quarter, the Company transitioned the variable rate base on its senior secured credit facilities and related hedging interest rate caps from LIBOR to SOFR. This transition involved a SOFR-to-LIBOR rate mismatch between this debt and the 2019 interest rate caps for a portion of the second quarter, but the Company’s interest rate hedges remained highly effective throughout the transition and thereafter. This transition was accomplished through the Amendments to the Credit Agreement for the Company's senior secured credit facility debt and, for the Company's 2019 interest rate caps outstanding, through the the International Swaps and Derivatives Association (ISDA)'s Interbank Offered Rate (IBOR) Fallbacks Supplement and IBOR Fallbacks Protocol which were established in anticipation of the cessation of LIBOR. That ISDA protocol incorporated fallbacks for derivatives linked to LIBOR which facilitated their transition to a replacement reference rate. The Company has adhered to this ISDA protocol and as of June 30, 2023 has transitioned all of its LIBOR-based derivative exposure to SOFR.
Fair Value of Financial Instruments	Interest rate cap agreements are recorded at fair value estimated from valuation models utilizing the income approach and commonly accepted valuation techniques that use inputs from closing prices for similar assets and liabilities in active markets as well as other relevant observable market inputs at quoted intervals such as current interest rates, forward yield curves, implied volatility and credit default swap pricing. The Company does not believe the ultimate amount that could be realized upon settlement of these interest rate cap agreements would be materially different from the fair value estimates currently reported.
New Accounting Standards	New accounting standards New standards recently adopted In March 2020, the FASB issued Accounting Standards Update (ASU) No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASU No. 2020-04 provides optional expedients and exceptions for applying U.S. GAAP to contract modifications and hedging relationships, subject to certain criteria, that reference LIBOR or another rate that is expected to be discontinued. The amendments in this ASU were effective beginning on March 12, 2020, and the Company could elect to apply the amendments prospectively through December 31, 2022. In December 2022, the FASB issued ASU No. 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848, which extended the election date to December 31, 2024. Effective January 1, 2022 certain LIBOR tenors that do not affect the Company, including the one-week and two-month U.S. dollar LIBOR rate, ceased or became non-representative. The remaining U.S. dollar LIBOR tenors ceased or became non-representative effective July 1, 2023. This change will have no impact on the Company's ability to borrow. The application of this ASU did not have a material impact on its consolidated financial statements. See Note 7 for further discussion of the Company's debt.

Condensed consolidated interim financial statements Condensed consolidaed interim financial statements (Policies)

9 Months Ended

Sep. 30, 2023

Condensed consolidated interim financial statements

Condensed consolidated interim financial statementsThe unaudited condensed consolidated interim financial statements included in this report are prepared by the Company. In the opinion of management, all adjustments necessary for a fair presentation of the results of operations are reflected in these condensed consolidated interim financial statements. All significant intercompany accounts and transactions have been eliminated. The preparation of these financial statements requires management to make estimates and assumptions that affect the reported amounts of revenues, expenses, assets, liabilities, contingencies and noncontrolling interests subject to put provisions. The most significant estimates and assumptions underlying these financial statements and accompanying notes generally involve revenue recognition and accounts receivable, certain fair value estimates, accounting for income taxes and loss contingencies. The results of operations reflected in these interim financial statements may not necessarily be indicative of annual operating results. These condensed consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 (2022 10-K). Prior period classifications conform to the current period presentation. The Company has evaluated subsequent events through the date these condensed consolidated interim financial statements were issued and has included all necessary adjustments and disclosures.

Revenue

There are significant uncertainties associated with estimating revenue, many of which take several years to resolve. These estimates are subject to ongoing insurance coverage changes, geographic coverage differences, differing interpretations of contract coverage and other payor issues, as well as patient issues, including determination of applicable primary and secondary coverage, changes in patient insurance coverage and coordination of benefits. As these estimates are refined over time, both positive and negative adjustments to revenue are recognized in the current period.

Dialysis patient service revenues. Revenues are recognized based on the Company’s estimate of the transaction price the Company expects to collect as a result of satisfying its performance obligations. Dialysis patient service revenues are recognized in the period services are provided based on these estimates. Revenues consist primarily of payments from government and commercial health plans for dialysis services provided to patients.

Other revenues. Other revenues consist of revenues earned by the Company's non-dialysis ancillary services as well as fees for management and administrative services to outpatient dialysis businesses that the Company does not consolidate. Other revenues are estimated in the period services are provided. The Company's integrated kidney care (IKC) revenues include revenues earned under risk-based arrangements, including value-based care (VBC) arrangements. Under its VBC arrangements, the Company assumes full or shared financial risk for the total medical cost of care for patients below or above a benchmark. The benchmarks against which the Company incurs profit or loss on these contracts are typically based on the underlying premiums paid to the insuring entity (the Company's counterparty), with adjustments where applicable, or on trended or adjusted medical cost targets.

Earnings Per Share

Basic earnings per share is calculated by dividing net income attributable to the Company by the weighted average number of common shares outstanding. Weighted average common shares outstanding include restricted stock unit awards that are no longer subject to forfeiture because the recipients have satisfied either the explicit vesting terms or retirement eligibility requirements.

Diluted earnings per share includes the dilutive effect of outstanding stock-settled stock appreciation rights and unvested stock units as computed under the treasury stock method.

Short-term and Long-term Investments

Debt securities. The Company's short-term debt investments are principally bank certificates of deposit with contractual maturities longer than three months but shorter than one year. The Company's long-term debt investments are bank time deposits with contractual maturities longer than one year. These debt securities are accounted for as held-to-maturity and recorded at amortized cost, which approximated their fair values at September 30, 2023 and December 31, 2022.

Equity securities. The Company holds certain equity investments that have readily determinable fair values from public markets. The Company's remaining short-term and long-term equity investments are held within a trust to fund existing obligations associated with the Company’s non-qualified deferred compensation plans.

Long-term debt

These cap agreements are designated as cash flow hedges and, as a result, changes in their fair values are reported in other comprehensive income. The original premiums paid for the caps are amortized to debt expense on a straight-line basis over the term of each cap agreement starting from its effective date. These cap agreements do not contain credit risk-contingent features.

In the second and third quarters of 2023 the Company entered into several forward interest rate cap agreements, described below, that have the economic effect of capping the Company's exposure to SOFR variable interest rate changes on specific portions of the Company's floating rate debt (2023 cap agreements). These 2023 cap agreements are designated as cash flow hedges and, as a result, changes in their fair values will be reported in other comprehensive income. These 2023 cap agreements, do not contain credit-risk contingent features, and become effective and expire as described in the table below. Certain of these 2023 cap agreements have notional amounts that amortize downward over time.

On October 18, 2023, the Company entered into several forward interest rate cap agreements with an aggregate notional amount of $500,000 that become effective on June 28, 2024 and expire on December 31, 2026, and a forward interest rate cap agreement with an aggregate notional amount of $250,000 that becomes effective on December 31, 2024 and expires on December 31, 2025 (together, the October 2023 cap agreements). These October 2023 cap agreements have the economic effect of capping the Company's exposure to SOFR variable interest rate changes on specific portions of the Company's floating rate debt and do not contain credit-risk contingent features. Additionally, the October 2023 cap agreements are designated as cash flow hedges and, as a result, changes in their fair values will be reported in other comprehensive income.

Finally, during and as of the end of the second quarter, the Company transitioned the variable rate base on its senior secured credit facilities and related hedging interest rate caps from LIBOR to SOFR. This transition involved a SOFR-to-LIBOR rate mismatch between this debt and the 2019 interest rate caps for a portion of the second quarter, but the Company’s interest rate hedges remained highly effective throughout the transition and thereafter.

This transition was accomplished through the Amendments to the Credit Agreement for the Company's senior secured credit facility debt and, for the Company's 2019 interest rate caps outstanding, through the the International Swaps and Derivatives Association (ISDA)'s Interbank Offered Rate (IBOR) Fallbacks Supplement and IBOR Fallbacks Protocol which were established in anticipation of the cessation of LIBOR. That ISDA protocol incorporated fallbacks for derivatives linked to LIBOR which facilitated their transition to a replacement reference rate. The Company has adhered to this ISDA protocol and as of June 30, 2023 has transitioned all of its LIBOR-based derivative exposure to SOFR.

Fair Value of Financial Instruments

Interest rate cap agreements are recorded at fair value estimated from valuation models utilizing the income approach and commonly accepted valuation techniques that use inputs from closing prices for similar assets and liabilities in active markets as well as other relevant observable market inputs at quoted intervals such as current interest rates, forward yield curves, implied volatility and credit default swap pricing. The Company does not believe the ultimate amount that could be realized upon settlement of these interest rate cap agreements would be materially different from the fair value estimates currently reported.

New Accounting Standards

New accounting standards

New standards recently adopted

In March 2020, the FASB issued Accounting Standards Update (ASU) No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASU No. 2020-04 provides optional expedients and exceptions for applying U.S. GAAP to contract modifications and hedging relationships, subject to certain criteria, that reference LIBOR or another rate that is expected to be discontinued. The amendments in this ASU were effective beginning on March 12, 2020, and the Company could elect to apply the amendments prospectively through December 31, 2022. In December 2022, the FASB issued ASU No. 2022-06, Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848, which extended the election date to December 31, 2024. Effective January 1, 2022 certain LIBOR tenors that do not affect the Company, including the one-week and two-month U.S. dollar LIBOR rate, ceased or became non-representative. The remaining U.S. dollar LIBOR tenors ceased or became non-representative effective July 1, 2023. This change will have no impact on the Company's ability to borrow. The application of this ASU did not have a material impact on its consolidated financial statements. See Note 7 for further discussion of the Company's debt.