Credit Agreement and Senior Notes (Tables)

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Summary of Senior Notes

At December 31, 2013, our senior notes were comprised of the following debt issues:

	Principal Amount			Interest Rate		Semiannual Interest Payment Dates
Debt Issue	(In millions)		Maturity Date	Coupon	Effective
5.15% Senior Notes due 2014	$	250.0	September 1, 2014	5.15%	5.18%	March 1 and September 1
4.875% Senior Notes due 2015	$	250.0	July 1, 2015	4.875%	4.90%	January 1 and July 1
5.875% Senior Notes due 2019	$	500.0	May 1, 2019	5.875%	5.89%	May 1 and November 1
3.45% Senior Notes due 2023	$	250.0	November 1, 2023	3.45%	3.50%	May 1 and November 1
5.70% Senior Notes due 2039	$	500.0	October 15, 2039	5.70%	5.75%	April 15 and October 15
4.875% Senior Notes due 2043	$	750.0	November 1, 2043	4.875%	4.89%	May 1 and November 1

Summary of Carrying Value of Senior Notes

At December 31, 2013 and 2012, the carrying value of our senior notes was as follows:

	December 31,
	2013		2012
	(In thousands)
5.15% Senior Notes due 2014	$	249,954	$	249,882
4.875% Senior Notes due 2015		249,898		249,837
5.875% Senior Notes due 2019		499,551		499,480
3.45% Senior Notes due 2023		248,988		—
5.70% Senior Notes due 2039		496,919		496,867
4.875% Senior Notes due 2043		748,833		—
Total senior notes, net of unamortized discount	$	2,494,143	$	1,496,066
Less: Current portion of long-term debt		249,954		—
Total Long-term debt	$	2,244,189	$	1,496,066

Aggregate Maturities of Senior Notes

As of December 31, 2013, the aggregate annual maturity of our senior notes was as follows:

	Aggregate Principal Amount
Years Ending December 31,	(In thousands)
2014	$	250,000
2015		250,000
2016		—
2017		—
2018		—
Thereafter		2,000,000
Total maturities of senior notes		2,500,000
Less: unamortized discounts		(5,857	)
Total maturities of senior notes, net of unamortized discount	$	2,494,143