Contract Settlement and Termination Agreement with Freeport-McMoRan Inc - Additional Information (Detail) - Noble Corp [Member] - FCX settlement [Member] $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Contract Settlement And Termination Agreement [Line Items]
Revenue recognized related to contingent payments	$ (7.9)
Estimated fair value of contingent payments	$ 6.5