Debt (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Aug. 23, 2011	Dec. 31, 2010
Long-term debt
Senior Notes		$ 700,000
Revolving credit facilities	(80,408)		(70,605)
Other	1,712		2,676
Long-term Debt	4,623,816		4,443,144
Current portion of long-term debt	275,326		1,379,018
Long-term debt, Noncurrent	4,348,490		3,064,126
5.375% Senior Notes Due August 2012 [Member]
Long-term debt
Senior Notes	274,604		273,977
Current portion of long-term debt	274,600
6.15% Senior Notes Due February 2018 [Member]
Long-term debt
Senior Notes	967,490		966,276
9.25% Senior Notes Due January 2019 [Member]
Long-term debt
Senior Notes	1,125,000		1,125,000
5.00% senior notes due September 2020 [Member]
Long-term debt
Senior Notes	697,343		697,037
4.625% senior notes due September 2021 [Member]
Long-term debt
Senior Notes	697,667		0
0.94% Senior Exchangeable Notes Due May 2011 [Member]
Long-term debt
0.94% senior exchangeable notes due May 2011	0		1,378,178
Current portion of long-term debt	1,400,000
Revolving Credit Facilities [Member]
Long-term debt
Revolving credit facilities	$ 860,000		$ 0