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Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, € in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  |
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Apr. 30, 2019 USD ($) | Apr. 30, 2019 EUR (€) | Apr. 30, 2018 USD ($) | Apr. 30, 2018 EUR (€) | Sep. 30, 2020 USD ($) | Jun. 30, 2020 USD ($) | Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Sep. 30, 2018 USD ($) | Dec. 31, 2020 USD ($) Office Country $ / shares shares | Dec. 31, 2019 USD ($) $ / shares shares | Dec. 31, 2018 USD ($) $ / shares shares | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013 | Aug. 31, 2019 shares | Mar. 31, 2019 | Aug. 03, 2018 shares | Jul. 28, 2016 shares
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of offices worldwide (over) | Office |  |  |  |  |  |  |  |  |  | 2,200 |  |  |  |  |  |  |  |  |  |  |
Number of countries and territories | Country |  |  |  |  |  |  |  |  |  | 75 |  |  |  |  |  |  |  |  |  |  |
Investments value |  |  |  |  |  |  |  |  |  | $ 106,600,000 | $ 97,800,000 | $ 161,400,000 |  |  |  |  |  |  |  |  |
Unremitted earning from investments |  |  |  |  |  |  |  |  |  | $ 8,000,000.0 | 3,400,000 |  |  |  |  |  |  |  |  |  |
Payment terms |  |  |  |  |  |  |  |  |  | 60 days |  |  |  |  |  |  |  |  |  |  |
Description of timing |  |  |  |  |  |  |  |  |  | Our client contracts are generally short-term in nature with a term of one year or less. The timing between satisfaction of the performance obligation, invoicing and payment is not significant. |  |  |  |  |  |  |  |  |  |  |
Deferred revenue |  |  |  |  |  |  |  |  |  | $ 34,900,000 | 44,500,000 |  |  |  |  |  |  |  |  |  |
Advertising expenses |  |  |  |  |  |  |  |  |  | 22,200,000 | 25,700,000 | 27,900,000 |  |  |  |  |  |  |  |  |
Restructuring costs |  |  |  |  |  |  |  |  |  | 110,700,000 | 42,000,000.0 | 39,300,000 |  |  |  |  |  |  |  |  |
Operating lease right-of-use asset impairment |  |  |  |  |  |  |  |  |  | 27,300,000 |  |  |  |  |  |  |  |  |  |  |
Costs paid, utilized or transferred |  |  |  |  |  |  |  |  |  | 71,900,000 | 50,200,000 |  |  |  |  |  |  |  |  |  |
Reserve will be paid by end of period |  |  |  |  |  |  |  |  |  | 46,100,000 | 7,300,000 | 15,500,000 |  |  |  |  |  |  |  |  |
Consolidated amortization expense related to intangibles |  |  |  |  |  |  |  |  |  | 27,200,000 | 29,800,000 | 35,100,000 |  |  |  |  |  |  |  |  |
2021 |  |  |  |  |  |  |  |  |  | 16,800,000 |  |  |  |  |  |  |  |  |  |  |
2022 |  |  |  |  |  |  |  |  |  | 13,400,000 |  |  |  |  |  |  |  |  |  |  |
2023 |  |  |  |  |  |  |  |  |  | 10,700,000 |  |  |  |  |  |  |  |  |  |  |
2024 |  |  |  |  |  |  |  |  |  | 8,400,000 |  |  |  |  |  |  |  |  |  |  |
2025 |  |  |  |  |  |  |  |  |  | 6,300,000 |  |  |  |  |  |  |  |  |  |  |
Non-cash impairment charge loss |  |  |  |  | $ 0 |  | $ 0 |  | $ 0 | 66,800,000 | 64,000,000.0 |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  |  | 1,225,800,000 | 1,260,100,000 | 1,297,100,000 |  |  |  |  |  |  |  |  |
Percentage interest acquired |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 51.00% |  |
Percentage of ownership in Swiss franchise |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 49.00% |  |
Swiss franchise investment portfolio market value |  |  |  |  |  |  |  |  |  |  |  | 219,900,000 |  |  |  |  |  |  |  |  |
Swiss franchise realized gains |  |  |  |  |  |  |  |  |  | 0.0 | 300,000 | 12,700,000 |  |  |  |  |  |  |  |  |
Swiss franchise realized losses |  |  |  |  |  |  |  |  |  | 0.0 | 200,000 | 2,100,000 |  |  |  |  |  |  |  |  |
Net capitalized software balance |  |  |  |  |  |  |  |  |  | 19,200,000 | 7,500,000 |  |  |  |  |  |  |  |  |  |
Amortization expense related to capitalized software cost |  |  |  |  |  |  |  |  |  | $ 1,800,000 | $ 2,000,000.0 | $ 1,500,000 |  |  |  |  |  |  |  |  |
Shares authorized to be repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,000,000.0 |  | 6,000,000.0 | 6,000,000.0
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  | 3,400,000 | 2,400,000 | 5,700,000 |  |  |  |  |  |  |  |  |
Total cost of shares repurchased |  |  |  |  |  |  |  |  |  | $ 264,700,000 | $ 203,000,000.0 | $ 500,700,000 |  |  |  |  |  |  |  |  |
Dividends declared (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  | $ 2.26 | $ 2.18 | $ 2.02 |  |  |  |  |  |  |  |  |
Total dividend payments |  |  |  |  |  |  |  |  |  | $ 129,100,000 | $ 129,300,000 | $ 127,300,000 |  |  |  |  |  |  |  |  |
Net earnings, net of tax, attributable to noncontrolling interests |  |  |  |  |  |  |  |  |  | $ 39,900,000 | (40,600,000) | $ 42,000,000.0 |  |  |  |  |  |  |  |  |
CICE payroll tax credit |  |  |  |  |  |  |  |  |  |  |  | 6.00% | 7.00% | 6.00% | 6.00% | 6.00% | 4.00% |  |  |  |
Multiplier for payroll tax credits |  |  |  |  |  |  |  |  |  | 2.5 |  |  |  |  |  |  |  |  |  |  |
Payment period |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |  |
Net proceeds from sale of tax credits | $ 103,500,000 | € 92.0 | $ 234,500,000 | € 190.9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Standards Update 2016-13 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted |  |  |  |  |  |  |  |  |  | true |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, adoption date |  |  |  |  |  |  |  |  |  | Jan. 01, 2020 |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, immaterial effect |  |  |  |  |  |  |  |  |  | true |  |  |  |  |  |  |  |  |  |  |
Accounting Standards Update 2018-13 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted |  |  |  |  |  |  |  |  |  | true |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, adoption date |  |  |  |  |  |  |  |  |  | Jan. 01, 2020 |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, immaterial effect |  |  |  |  |  |  |  |  |  | true |  |  |  |  |  |  |  |  |  |  |
Accounting Standards Update 2018-15 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted |  |  |  |  |  |  |  |  |  | true |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, adoption date |  |  |  |  |  |  |  |  |  | Jan. 01, 2020 |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, immaterial effect |  |  |  |  |  |  |  |  |  | true |  |  |  |  |  |  |  |  |  |  |
Accounting Standards Update 2018-14 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, adopted |  |  |  |  |  |  |  |  |  | true |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, adoption date |  |  |  |  |  |  |  |  |  | Jan. 01, 2020 |  |  |  |  |  |  |  |  |  |  |
Change in accounting principle, accounting standards update, immaterial effect |  |  |  |  |  |  |  |  |  | true |  |  |  |  |  |  |  |  |  |  |
Noncontrolling Interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net earnings, net of tax, attributable to noncontrolling interests |  |  |  |  |  |  |  |  |  | $ 4,700,000 | $ (1,800,000) | $ 4,900,000 |  |  |  |  |  |  |  |  |
August 2019 Authorization |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  | 2,600,000 | 2,400,000 |  |  |  |  |  |  |  |  |  |
Shares remaining authorized for repurchase (in shares) | shares |  |  |  |  |  |  |  |  |  | 3,400,000 |  |  |  |  |  |  |  |  |  |  |
August 2018 Authorization |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  | 800,000 |  | 2,900,000 |  |  |  |  |  |  |  |  |
Shares remaining authorized for repurchase (in shares) | shares |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |
July 2016 Authorization |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares repurchased (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  | 2,800,000 |  |  |  |  |  |  |  |  |
Shares remaining authorized for repurchase (in shares) | shares |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |  |  |  |  |  |
Leasehold Improvements |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated useful lives |  |  |  |  |  |  |  |  |  | lesser of life of asset or expected lease term |  |  |  |  |  |  |  |  |  |  |
United Kingdom |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of goodwill over fair value of reporting unit |  |  |  |  |  |  |  |  |  | 12.00% |  |  |  |  |  |  |  |  |  |  |
United Kingdom | Discount Rates |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate for goodwill impairment test (as a percent) |  |  |  |  |  |  |  |  |  | 11.5 |  |  |  |  |  |  |  |  |  |  |
United Kingdom | Terminal Value Revenue Growth Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate for goodwill impairment test (as a percent) |  |  |  |  |  |  |  |  |  | 1.0 |  |  |  |  |  |  |  |  |  |  |
United Kingdom | Terminal Value OUP Margin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate for goodwill impairment test (as a percent) |  |  |  |  |  |  |  |  |  | 3.1 |  |  |  |  |  |  |  |  |  |  |
Netherlands |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of goodwill over fair value of reporting unit |  |  |  |  |  |  |  |  |  | 3.30% |  |  |  |  |  |  |  |  |  |  |
Netherlands | Discount Rates |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate for goodwill impairment test (as a percent) |  |  |  |  |  |  |  |  |  | 10.9 |  |  |  |  |  |  |  |  |  |  |
Netherlands | Terminal Value Revenue Growth Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate for goodwill impairment test (as a percent) |  |  |  |  |  |  |  |  |  | 2.0 |  |  |  |  |  |  |  |  |  |  |
Netherlands | Terminal Value OUP Margin |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate for goodwill impairment test (as a percent) |  |  |  |  |  |  |  |  |  | 3.5 |  |  |  |  |  |  |  |  |  |  |
Northern Europe | United Kingdom |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  |  | $ 100,200,000 | $ 97,300,000 |  |  |  |  |  |  |  |  |  |
Northern Europe | Netherlands |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  |  | $ 119,300,000 | 109,500,000 |  |  |  |  |  |  |  |  |  |
Northern Europe | Germany |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-cash impairment charge loss |  |  |  |  |  | $ 66,800,000 |  | $ 60,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  |  |  | $ 67,200,000 |  |  |  |  |  |  |  |  |  |
APME | New Zealand |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Non-cash impairment charge loss |  |  |  |  |  |  |  | $ 3,800,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of goodwill over fair value of reporting unit |  |  |  |  |  |  |  |  |  | 20.00% |  |  |  |  |  |  |  |  |  |  |
Remaining lease terms |  |  |  |  |  |  |  |  |  | 1 month |  |  |  |  |  |  |  |  |  |  |
Minimum | Furniture, Fixtures, and Autos |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated useful lives |  |  |  |  |  |  |  |  |  | 2 years |  |  |  |  |  |  |  |  |  |  |
Minimum | Computer Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated useful lives |  |  |  |  |  |  |  |  |  | 2 years |  |  |  |  |  |  |  |  |  |  |
Minimum | Discount Rates |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate for goodwill impairment test (as a percent) |  |  |  |  | 0.091 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Remaining lease terms |  |  |  |  |  |  |  |  |  | 11 years |  |  |  |  |  |  |  |  |  |  |
Maximum | Buildings |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated useful lives |  |  |  |  |  |  |  |  |  | 40 years |  |  |  |  |  |  |  |  |  |  |
Maximum | Furniture, Fixtures, and Autos |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated useful lives |  |  |  |  |  |  |  |  |  | 15 years |  |  |  |  |  |  |  |  |  |  |
Maximum | Computer Equipment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated useful lives |  |  |  |  |  |  |  |  |  | 15 years |  |  |  |  |  |  |  |  |  |  |
Maximum | Discount Rates |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate for goodwill impairment test (as a percent) |  |  |  |  | 0.135 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum | Netherlands |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of goodwill over fair value of reporting unit |  |  |  |  |  |  |  |  |  | 10.00% |  |  |  |  |  |  |  |  |  |  |
Customer relationships |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Useful life |  |  |  |  |  |  |  |  |  | 12 years |  |  |  |  |  |  |  |  |  |  |
Other |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Useful life |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |  |
Computer software | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Useful life |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |
Computer software | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Useful life |  |  |  |  |  |  |  |  |  |  | 10 years |  |  |  |  |  |  |  |  |  |
Euro-denominated notes | Estimate of fair value measurement | Significant Other Observable Inputs (Level 2) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of long-term debt |  |  |  |  |  |  |  |  |  | $ 1,094,500,000 | $ 1,062,500,000 |  |  |  |  |  |  |  |  |  |
Euro-denominated notes | Carrying value | Significant Other Observable Inputs (Level 2) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of long-term debt |  |  |  |  |  |  |  |  |  | 1,159,100,000 | 1,002,900,000 |  |  |  |  |  |  |  |  |  |
Allowance for doubtful accounts |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bad debt expense |  |  |  |  |  |  |  |  |  | 20,300,000 | 21,800,000 | $ 23,000,000.0 |  |  |  |  |  |  |  |  |
Write-offs |  |  |  |  |  |  |  |  |  | $ 17,800,000 | $ 19,100,000 | $ 12,000,000.0 |  |  |  |  |  |  |  |  |

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