BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The accompanying unaudited Condensed Consolidated Financial Statements include the accounts of Stericycle, Inc. and its subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The Company's Condensed Consolidated Financial Statements were prepared in accordance with U.S. GAAP and include the assets, liabilities, revenues and expenses of all wholly owned subsidiaries and majority-owned subsidiaries over which the Company exercises control. Outside shareholders' interests in subsidiaries are shown on the Condensed Consolidated Financial Statements as “Noncontrolling interests." The accompanying unaudited Condensed Consolidated Financial Statements as of September 30, 2020 and for the three and nine months ended September 30, 2020 and 2019 have been prepared pursuant to the rules and regulations of the SEC for interim reporting and, therefore, do not include all information and footnote disclosures normally included in audited financial statements prepared in conformity with U.S. GAAP. In the opinion of management, however, all adjustments, consisting of normal recurring adjustments necessary to present fairly the results of operations, financial position and cash flows have been made. These Condensed Consolidated Financial Statements should be read in conjunction with the consolidated financial statements and notes thereto included in the 2019 Form 10-K. The results of operations for any interim period are not necessarily indicative of the results of operations to be expected for the full year or any other period.
Use of Estimates	Use of Estimates: The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Some areas where the Company makes estimates include its allowance for doubtful accounts, credit memo reserve, accrued employee health and welfare benefits, environmental liabilities, stock-based compensation expense, income tax liabilities, accrued auto and workers’ compensation insurance claims, operating lease ROU assets and lease liabilities, intangible asset valuations, and long-lived asset and goodwill impairment assessments. Actual results could differ from the Company's estimates.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts: The Company reports accounts receivable at their net realizable value, which is management’s best estimate of the cash that will ultimately be received. The Company maintains an allowance for doubtful accounts to reflect the expected uncollectability of accounts receivable based on historical collection data and specific risks identified among uncollected accounts, as well as management’s expectation of future economic conditions. If current or expected future economic trends, events, or changes in circumstances indicate that specific receivable balances may be impaired, further consideration is given to the collectability of those balances and the allowance is adjusted accordingly. The adequacy of allowances for uncollectible accounts is reviewed at least quarterly and adjusted as necessary based on such reviews. Management’s judgment is required to assess the collectability of an account, based on detailed analysis of the aging of the receivables, the creditworthiness of the Company’s customers, historical collection trends, and current and future expected economic trends. Accounts receivable written off in subsequent periods can differ from the allowance for doubtful accounts provided, but historically the Company’s provision has been adequate.
New Accounting Standards Adopted and Issued	Adoption of New Accounting Standards Financial Instrument Credit Losses In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (“ASU 2016-13”) associated with the measurement of credit losses on financial instruments. ASU 2016-13 replaces the prior incurred loss impairment methodology of recognizing credit losses when a loss was probable, with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to assess credit loss estimates. The amended guidance was effective for the Company on January 1, 2020. The Company recognized a net decrease to Retained earnings in the Condensed Consolidated Financial Statements of $2.5 million as of January 1, 2020 for the cumulative effect of adopting ASU 2016-13. Implementation Costs Incurred in a Cloud Computing Arrangement In August 2018, the FASB issued ASU 2018-15, “Intangibles - Goodwill and Other - Internal Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract” (“ASU 2018-15”). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs for internal-use software. The accounting for any hosting contract is unchanged. ASU 2018-15 was effective on January 1, 2020 and was adopted prospectively for implementation costs incurred after the date of adoption. The adoption of ASU 2018-15 did not have a material impact on the Condensed Consolidated Financial Statements. Accounting Standards Issued But Not Yet Adopted Simplifying the Accounting for Income Taxes In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes” (“ASU 2019-12”). ASU 2019-12 attempts to simplify aspects of accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for public business entities for fiscal years beginning after December 15, 2020, including interim periods within that fiscal year. Early adoption is permitted for all entities. The Company plans to adopt ASU 2019-12 effective January 1, 2021.

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

9 Months Ended

Sep. 30, 2020

Basis of Presentation: The accompanying unaudited Condensed Consolidated Financial Statements include the accounts of Stericycle, Inc. and its subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The Company's Condensed Consolidated Financial Statements were prepared in accordance with U.S. GAAP and include the assets, liabilities, revenues and expenses of all wholly owned subsidiaries and majority-owned subsidiaries over which the Company exercises control. Outside shareholders' interests in subsidiaries are shown on the Condensed Consolidated Financial Statements as “Noncontrolling interests."

The accompanying unaudited Condensed Consolidated Financial Statements as of September 30, 2020 and for the three and nine months ended September 30, 2020 and 2019 have been prepared pursuant to the rules and regulations of the SEC for interim reporting and, therefore, do not include all information and footnote disclosures normally included in audited financial statements prepared in conformity with U.S. GAAP. In the opinion of management, however, all adjustments, consisting of normal recurring adjustments necessary to present fairly the results of operations, financial position and cash flows have been made. These Condensed Consolidated Financial Statements should be read in conjunction with the consolidated financial statements and notes thereto included in the 2019 Form 10-K. The results of operations for any interim period are not necessarily indicative of the results of operations to be expected for the full year or any other period.

Use of Estimates

Use of Estimates: The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Some areas where the Company makes estimates include its allowance for doubtful accounts, credit memo reserve, accrued employee health and welfare benefits, environmental liabilities, stock-based compensation expense, income tax liabilities, accrued auto and workers’ compensation insurance claims, operating lease ROU assets and lease liabilities, intangible asset valuations, and long-lived asset and goodwill impairment assessments. Actual results could differ from the Company's estimates.

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts: The Company reports accounts receivable at their net realizable value, which is management’s best estimate of the cash that will ultimately be received. The Company maintains an allowance for doubtful accounts to reflect the expected uncollectability of accounts receivable based on historical collection data and specific risks identified among uncollected accounts, as well as management’s expectation of future economic conditions. If current or expected future economic trends, events, or changes in circumstances indicate that specific receivable balances may be impaired, further consideration is given to the collectability of those balances and the allowance is adjusted accordingly. The adequacy of allowances for uncollectible accounts is reviewed at least quarterly and adjusted as necessary based on such reviews. Management’s judgment is required to assess the collectability of an account, based on detailed analysis of the aging of the receivables, the creditworthiness of the Company’s customers, historical collection trends, and current and future expected economic trends.

Accounts receivable written off in subsequent periods can differ from the allowance for doubtful accounts provided, but historically the Company’s provision has been adequate.

New Accounting Standards Adopted and Issued

Adoption of New Accounting Standards

Financial Instrument Credit Losses

In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (“ASU 2016-13”) associated with the measurement of

credit losses on financial instruments. ASU 2016-13 replaces the prior incurred loss impairment methodology of recognizing credit losses when a loss was probable, with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to assess credit loss estimates. The amended guidance was effective for the Company on January 1, 2020. The Company recognized a net decrease to Retained earnings in the Condensed Consolidated Financial Statements of $2.5 million as of January 1, 2020 for the cumulative effect of adopting ASU 2016-13.

Implementation Costs Incurred in a Cloud Computing Arrangement

In August 2018, the FASB issued ASU 2018-15, “Intangibles - Goodwill and Other - Internal Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract” (“ASU 2018-15”). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs for internal-use software. The accounting for any hosting contract is unchanged. ASU 2018-15 was effective on January 1, 2020 and was adopted prospectively for implementation costs incurred after the date of adoption. The adoption of ASU 2018-15 did not have a material impact on the Condensed Consolidated Financial Statements.

Accounting Standards Issued But Not Yet Adopted

Simplifying the Accounting for Income Taxes

In December 2019, the FASB issued ASU 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes” (“ASU 2019-12”). ASU 2019-12 attempts to simplify aspects of accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. ASU 2019-12 is effective for public business entities for fiscal years beginning after December 15, 2020, including interim periods within that fiscal year. Early adoption is permitted for all entities. The Company plans to adopt ASU 2019-12 effective January 1, 2021.