Subsequent Event (Detail) (Subsequent Event [Member], USD $)	9 Months Ended
	Sep. 29, 2012
Subsequent Event [Line Items]
Percentage of Working Interest to be acquired under agreement	50.00%
Expected investment over the next three fiscal years	$ 542,000,000
Expected investment over the term of agreement	$ 3,640,000,000
Minimum [Member]
Subsequent Event [Line Items]
Estimated year of agreement	13 years
Maximum [Member]
Subsequent Event [Line Items]
Estimated year of agreement	22 years