Segment and Related Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	$ 329,585	$ 266,212	$ 278,142	$ 362,976	$ 410,156	$ 385,153	$ 894,783	$ 611,973	$ 1,236,915	$ 2,302,065	$ 3,352,252
Identifiable Assets	10,794,659				11,440,117				10,794,659	11,440,117
Africa
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									48,228	1,803	0
Identifiable Assets	0				673,486				0	673,486
Argentina
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	51,627	111,589
Identifiable Assets	0				0				0	0
Australia
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									12,262	89,847	204,822
Identifiable Assets	257,415				0				257,415	0
Brazil
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	27,640	78,683
Identifiable Assets	25,645				25,474				25,645	25,474
Brunei
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									45,450	42,710	0
Identifiable Assets	119				312,494				119	312,494
Bulgaria
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									55,145	78,985	0
Identifiable Assets	657,806				0				657,806	0
Canada
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									1,639	0	0
Identifiable Assets	238,902				0				238,902	0
Curacao
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	0	0
Identifiable Assets	647,554				0				647,554	0
Denmark
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									44,671	46,342	77,934
Identifiable Assets	250,851				250,776				250,851	250,776
Gabon
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	23,385	90,082
Identifiable Assets	8,378				0				8,378	0
Libya
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	0	136,406
Identifiable Assets	0				0				0	0
Malaysia
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									131,696	168,826	149,597
Identifiable Assets	293,297				747,059				293,297	747,059
Mexico
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	0	0
Identifiable Assets	27,391				0				27,391	0
Qatar
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									16,488	608	0
Identifiable Assets	0				263,108				0	263,108
Saudi Arabia
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									140,453	120,132	226,251
Identifiable Assets	455,296				443,965				455,296	443,965
Singapore
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	0	0
Identifiable Assets	911,515				230,897				911,515	230,897
Suriname
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									13,034	0	0
Identifiable Assets	0				0				0	0
Tanzania
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									1,526	48,394	0
Identifiable Assets	0				0				0	0
The Netherlands
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	42	67,765
Identifiable Assets	0				0				0	0
Turkey
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									(3)	0	97,065
Identifiable Assets	0				0				0	0
United Arab Emirates
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									99,825	86,446	67,117
Identifiable Assets	590,863				591,306				590,863	591,306
United Kingdom
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									209,338	95,621	87,896
Identifiable Assets	894,902				1,475,651				894,902	1,475,651
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									417,163	1,404,365	1,941,485
Identifiable Assets	5,534,725				6,399,119				5,534,725	6,399,119
Other
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues									0	15,292	$ 15,560
Identifiable Assets	$ 0				$ 26,782				$ 0	$ 26,782