Long Term Debt (Tables)

12 Months Ended

Dec. 31, 2011

Long-Term Debt [Abstract]

Summary of long-term debt comprised

Name of Issue	Aggregate Principal Amount (In millions)	Maturity Date	Stated Interest Rate	Semiannual Interest Payment Dates
5.15% Senior Notes	$250.0	September 1, 2014	5.15%	March 1 and September 1
4.875% Senior Notes	$250.0	July 1, 2015	4.875%	January 1 and July 1
5.875% Senior Notes	$500.0	May 1, 2019	5.875%	May 1 and November 1
5.70% Senior Notes	$500.0	October 15, 2039	5.70%	April 15 and October 15

Long-Term Debt

	December 31,
	2011		2010
	(In thousands)
5.15% Senior Notes	$	249,811	$	249,745
4.875% Senior Notes		249,779		249,724
5.875% Senior Notes		499,414		499,351
5.70% Senior Notes		496,819		496,773
Total	$	1,495,823	$	1,495,593

Aggregate maturities of long-term debt for each of the five years

(In thousands)
2012	$	—
2013		—
2014		249,811
2015		249,779
2016		—
Thereafter		996,233
Total	$	1,495,823