Asset Impairments - Additional Information (Detail)	3 Months Ended								6 Months Ended	12 Months Ended			36 Months Ended
	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($) Rigs	Sep. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) Rigs	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($) Rigs	Dec. 31, 2015 USD ($) Rigs	Dec. 31, 2014 USD ($) Rigs	Dec. 31, 2016 Rigs
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired										30			30
Impairment of assets | $	$ 678,100,000	$ 499,400,000	$ 2,600,000	$ 358,500,000						$ 678,145,000	$ 860,441,000	$ 109,462,000
Number of rigs sold													20
Number of rigs cold stacked										8			8
Number of impaired rigs, currently operating under contract													2
2016 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs evaluated for impairment										15			15
Number of rigs impaired										8			8
Impaired long-lived assets held and used, method for determining fair value										We estimated the fair value of the 2016 Impaired Rigs using an income approach. The fair value of each rig was estimated based on a calculation of the rig’s discounted future net cash flows over its remaining economic life, which utilized significant unobservable inputs, including, but not limited to, assumptions related to estimated dayrate revenue, rig utilization, estimated reactivation and regulatory survey costs, as well as estimated proceeds that may be received on ultimate disposition of the rig. Our fair value estimates were representative of Level 3 fair value measurements due to the significant level of estimation involved and the lack of transparency as to the inputs used.
Impairment of assets | $									$ 670,000,000	$ 670,000,000
2015 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs evaluated for impairment		25									25
Number of rigs impaired		17									17
Impaired long-lived assets held and used, method for determining fair value										We estimated the fair value of 16 of the 2015 Impaired Rigs utilizing a market approach, which required us to estimate the value that would be received for each rig in the principal or most advantageous market for that rig in an orderly transaction between market participants. Such estimates were based on various inputs, including historical contracted sales prices for similar rigs in our fleet, nonbinding quotes from rig brokers and/or indicative bids, where applicable. We estimated the fair value of the one remaining 2015 Impaired Rig using an income approach, as discussed above. Our fair value estimates are representative of Level 3 fair value measurements due to the significant level of estimation involved and the lack of transparency as to the inputs used.
Impairment of assets | $		$ 499,400,000	$ 2,600,000	$ 358,500,000							$ 860,400,000
2014 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs evaluated for impairment					6							6
Impaired long-lived assets held and used, method for determining fair value										We determined the fair value of the 2014 Impaired Rigs by applying a combination of income and market approaches which were representative of Level 3 fair value measurements due to the significant level of estimation involved and the lack of transparency as to the inputs used.
Ultra-deep Water Rigs [Member] | 2016 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired										3			3
Ultra-deep Water Rigs [Member] | 2015 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired		2									2
Deep Water Rigs [Member] | 2016 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired										3			3
Deep Water Rigs [Member] | 2015 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired		1									1
Mid-Water Drilling Rigs [Member] | 2016 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired										2			2
Mid-Water Drilling Rigs [Member] | 2015 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired		9									9
Jack-ups [Member] | 2015 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired		5									5
Mid-Water Rigs [Member] | 2014 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Impairment of assets | $					$ 0	$ 109,500,000	$ 0	$ 0
Number of rigs subject to scrap					6							6
Rig with Fair Values Estimated Using Market Approach [Member] | 2015 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Total rigs estimated using market approach		16									16
Rig with Fair Values Estimated Using Income Approach [Member] | 2015 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Total rigs estimated using income approach		1									1