Employee Benefit Plans - Narrative (Details) $ in Millions		3 Months Ended			6 Months Ended
	Mar. 23, 2020 USD ($)	Dec. 31, 2020 USD ($) shares	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 31, 2020 USD ($) plan shares	Dec. 31, 2019 USD ($) shares
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Reclassification Adjustment, before Tax	$ (13.4)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Increase (Decrease) for Plan Amendment	$ (14.6)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment			$ (5.8)
Amortization expense		$ 0.6	$ 0.6		$ 1.2
Other Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Multiemployer plans, number of plans | plan					9
Restated and Amended 401K Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, employer matching contribution, percent of eligible income					4.00%
Defined Contribution Plan, Number of Shares Contributed | shares		162,259		54,025	270,685	109,649
Defined Contribution Plan, Employer Discretionary Contribution Amount		$ 0.8		$ 0.6	$ 1.2	$ 1.4
Defined Benefit Plan, Plan Assets, Contributions by Employer		$ 0.6			$ 1.3