Goodwill (Schedule of Goodwill) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)
Goodwill [Roll Forward]
Balance at December 31, 2015	$ 2,803
Foreign currency translation adjustments	61
Balance at March 31, 2016	2,864
Land Drilling Rigs [Member]
Goodwill [Roll Forward]
Balance at December 31, 2015	0
Foreign currency translation adjustments	0
North America [Member]
Goodwill [Roll Forward]
Balance at December 31, 2015	1,756
Foreign currency translation adjustments	52
Balance at March 31, 2016	1,808
MENA/ Asia Pacific [Member]
Goodwill [Roll Forward]
Balance at December 31, 2015	190
Foreign currency translation adjustments	2
Balance at March 31, 2016	192
Europe/ SSA/ Russia [Member]
Goodwill [Roll Forward]
Balance at December 31, 2015	573
Foreign currency translation adjustments	6
Balance at March 31, 2016	579
Latin America [Member]
Goodwill [Roll Forward]
Balance at December 31, 2015	284
Foreign currency translation adjustments	1
Balance at March 31, 2016	$ 285