Fresh Start Accounting - Fresh Start Adjustments (Detail) $ in Millions	Apr. 23, 2021 USD ($)
Fresh Start Adjustment [Line Items]
Fair value adjustment of rig spare parts and supplies	$ (7.2)
Write-off of current deferred contract assets	(27.3)
Fair value adjustment to drilling and other property and equipment net of accumulated depreciation	(2,712.1)
Fair value adjustment of BOP finance lease assets	(8.4)
Write-off of current deferred contract liabilities	(56.4)
Fair value adjustment to current other lease liabilities	0.4
Write-off of non-current deferred contract liabilities	(11.1)
Fair value adjustment of non-current other lease liabilities	1.3
ASC 740
Fresh Start Adjustment [Line Items]
Adjustment to deferred taxes	$ (34.4)