Income Tax - Additional Information (Detail) $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($)
Income Tax Disclosure [Abstract]
Income tax benefit from carryback of net operating losses	$ (9.7)

Income tax expense benefit from carryback of net operating losses.

No definition available.

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Namespace Prefix:	do_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration