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Employee and Retiree Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Executive Retirement Plan
Defined Contribution Plan Disclosure [Line Items]
Liability for retirement plan	$ 3.7	$ 2.1
Profit Sharing Plan
Defined Contribution Plan Disclosure [Line Items]
Profit sharing contributions	$ 1.8	1.5	$ (0.8)
Thrift Plan
Defined Contribution Plan Disclosure [Line Items]
Company matching contribution (percent)	100.00%
Employee's maximum contribution matched by Company (percent)	6.00%
Profit sharing percentage 1	5.00%
Profit sharing percentage 2	7.00%
Profit sharing percentage 3	9.00%
Profit sharing contributions	$ 15.3	$ 12.9	$ 9.7

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Amount of labor-related expenses classified as other.

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