Operations by Business Segment and Geographic Area - Revenues and Long-Lived Assets by Location (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	$ 1,827,376	$ 1,318,049	$ 973,530
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Entity's Country of Domicile	955,228	874,614	943,515
Revenues	2,782,604	2,192,663	1,917,045
Long-Lived Assets	1,522,287	1,378,104	1,010,666
Foreign [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	914,715	825,465	527,588
Norway [Member]
Segment Reporting Information [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	461,863	310,891	212,854
Long-Lived Assets	474,408	436,043	165,942
West Africa [Member]
Segment Reporting Information [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	463,227	284,642	260,377
Long-Lived Assets	141,927	120,732	106,028
United Kingdom [Member]
Segment Reporting Information [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	334,319	256,565	156,114
Long-Lived Assets	85,434	65,830	70,730
Asia and Australia [Member]
Segment Reporting Information [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	290,821	217,094	136,518
Long-Lived Assets	65,012	72,518	76,835
Brazil [Member]
Segment Reporting Information [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	164,660	155,532	135,510
Long-Lived Assets	113,829	99,709	79,484
Other [Member]
Segment Reporting Information [Line Items]
Disclosure on Geographic Areas, Revenue from External Customers Attributed to Foreign Countries	112,486	93,325	72,157
Long-Lived Assets	34,105	30,633	28,569
United States [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 607,572	$ 552,639	$ 483,078