The amount of cash, securities, or other assets held by a third-party trustee pursuant to the terms of an agreement which assets are available to be used by beneficiaries to that agreement only within the specific terms thereof and which agreement is expected to terminate more than one year from the balance sheet date (or operating cycle, if longer) at which time the assets held-in-trust will be released or forfeited.

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A savings certificate entitling the Entity (that is, bearer) to receive interest at an established maturity date, based upon a fixed interest rate. A certificate of deposit may be issued in any denomination. Certificates of deposit are generally issued by commercial banks and, therefore, insured by the FDIC (up to the prescribed limit). Certificates of deposit generally restrict holders from withdrawing funds on demand without the incurrence of penalties. Generally, only certificates of deposit with original maturities of three months or less qualify as cash equivalents. Original maturity means original maturity to the entity holding the investment. As a related example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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Amount of cash inflow for proceeds from settlement of corporate-owned life insurance policy, classified as investing activities. Includes, but is not limited to, bank-owned life insurance policy.

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Investments (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended		12 Months Ended
Investments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Long-term investments:
Proceeds from Life Insurance Policy	$ 8.4	$ 15.6		$ 15.6
Assets held in rabbi trusts [Member]
Short-term investments:
Fair value of assets held under trust		6.7		6.6
Long-term investments:
Assets held in a rabbi trust		5.1		5.2
Long-term investments, unrealized gain		1.6	$ 1.4
Certificates of deposit
Long-term investments:
Long-term investments, unrealized gain		0.0	$ 0.0
Certificates of Deposit, at Carrying Value		13.7		37.2
Short-term investments \| Certificates of deposit \| Fair Value, Measurements, Recurring [Member]
Short-term investments:
Fair value of assets held under trust		13.7		37.2
Short-term investments \| Certificates of deposit \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Short-term investments:
Fair value of assets held under trust		$ 13.7		$ 37.2