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Accident and Workers' Compensation Insurance Liabilities (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Accident and Workers' Compensation Insurance Liabilities [Line Items] |  |
Excess Insurance Coverage Limit | $ 60.0 | $ 100.0
Trust fund requirements | 0.7 |
Debt Securities, Held-to-maturity | 1.5 | 1.5
Letters of Credit Outstanding, Amount | 13.0 |
Letter of credit due | 0.0 | 0.0
Excess Insurance Coverage Minimum Claims |  | 3.0
Excess Insurance Coverage Maximum Claims |  | 10.0
Aggregate Self-Insurance Corridor | 1.0 |
Aggregate Self-Insurance Corridor Claims Minimum [Member] | 2.0 |
Aggregate Self-Insurance Corridor Claims Maximum [Member] | 3.0 |
Auto Liability 50% Exposure Minimum [Member] | 5.0 |
Auto Liability 50% Exposure Maximum [Member] | 10.0 |
Auto liability retention limit minimum [Member] |  |
Accident and Workers' Compensation Insurance Liabilities [Line Items] |  |
Auto liability retention limit | 1.0 | 0.1
Auto liability retention limit maximum [Member] [Member] |  |
Accident and Workers' Compensation Insurance Liabilities [Line Items] |  |
Auto liability retention limit | 2.0 | 2.0
workers compensation retention limit minimum [Member] |  |
Accident and Workers' Compensation Insurance Liabilities [Line Items] |  |
Workers compensation retention limit | 1.0 | 0.5
workers compensation retention limit maximum [Member] |  |
Accident and Workers' Compensation Insurance Liabilities [Line Items] |  |
Workers compensation retention limit | $ 1.0 | $ 1.0

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- Definition Auto liability retention limit + References No definition available. + Details
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- Definition Excess Insurance Coverage Maximum Claims + References No definition available. + Details
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- Definition Amount of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563 + Details
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- Definition The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910 + Details
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