Drilling units

12 Months Ended

Dec. 31, 2012

Drilling units [Abstract]

Drilling units

Note 18 – Drilling units

(In US$ millions)	December 31, 2012		December 31, 2011
Cost		15,177		12,898
Accumulated depreciation		(2,283)		(1,675)
Net book value		12,894		11,223

Depreciation and amortization expense was $608 million, $547 million and $448 million for the years ended December 31, 2012, 2011 and 2010, respectively.