NOTES PAYABLE AND DEBT AND FINANCING ARRANGEMENTS (Detail) - The financing structure as at the balance sheet date (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Debt:
Adjustment to carrying value – impact of fair value hedge	$ 10,709	[1]	$ 17,675	[1]
Adjustment to carrying value – impact of fair value hedge	0		0
Carrying Value	3,275,000		3,450,000
Carrying Value	2,275,327	[1]	2,457,003	[1]
FiveYear Revolvers Expiring 2012 [Member]
Debt:
Total Commitment / Debt	0	[2]	1,000,000	[2]
Total In Use / Outstanding	0	[1],[2]	0	[1],[2]
Four Year Revolvers Expiring 2015 [Member]
Debt:
Total Commitment / Debt	1,000,000	[3]	0	[3]
Total In Use / Outstanding	0	[1],[3]	0	[1],[3]
Guaranteed Senior Notes 6.50 Percent Due 2012 [Member]
Debt:
Commitment / Debt	600,000	[4]	600,000	[4]
In Use / Outstanding	599,971	[1],[4]	599,294	[1],[4]
Senior Notes Due 2014 [Member]
Debt:
Commitment / Debt	600,000		600,000
In Use / Outstanding	597,501	[1]	596,579	[1]
Senior Notes One Due 2021 [Member]
Debt:
Commitment / Debt	400,000		0
In Use / Outstanding	395,963	[1]	0	[1]
Senior Notes Two Due 2021 [Member]
Debt:
Commitment / Debt	0		575,000
In Use / Outstanding	0	[1]	572,538	[1]
Senior Notes Due 2024 [Member]
Debt:
Commitment / Debt	350,000		350,000
In Use / Outstanding	348,592	[1]	348,482	[1]
Senior Notes Due 2027 [Member]
Debt:
Commitment / Debt	325,000		325,000
In Use / Outstanding	322,591	[1]	322,435	[1]
Senior Notes Total [Member]
Debt:
Commitment / Debt	3,275,000		3,450,000
In Use / Outstanding	2,264,618	[1]	2,439,328	[1]
Letter of Credit [Member]
Debt:
Total Commitment / Debt	4,000,000	[5],[6]	5,000,114	[5],[7]
Total In Use / Outstanding	$ 1,871,192	[1]	$ 2,395,242	[1]

[1] "In Use" and "Outstanding" data represent December 31, 2011 and 2010 accreted values.

[2] The 2012 5-year revolving credit facilities shared a $1 billion revolving credit sub-limit. This facility was terminated in December 2011 in connection with entering into new credit facilities.

[3] This Credit facility has a $1 billion revolving credit sub-limit.

[4] The 6.50% Guaranteed Senior Notes were repaid at maturity on January 15, 2012.

[5] The Company has the option to increase the size of the March 2011 Credit Agreement by an additional $500 million and the size of the facilities under the December 2011 Credit Agreements by an additional $500 million across both such facilities.

[6] At December 31, 2011 there were five available letter of credit facilities.

[7] At December 31, 2010 there were five available letter of credit facilities.