Debt (Tables)

Mar. 31, 2012

Debt [Abstract]

ComponentsOfDebt

	March 31,		December 31,
	2012		2011
	(in thousands)
Short-term debt:
7.15% Senior Notes due 2018	$                   1,200	$                  1,200
Total short-term debt	1,200	1,200
Long-term debt:
Variable rate (2.276% at December 31, 2011) unsecured revolving credit facility, expires February 2016	0	671,500
7.5% Senior Notes due 2018	600,000	600,000
7.35% Senior Notes due 2017	15,000	15,000
7.125% Senior Notes due 2017	25,000	25,000
7.15% Senior Notes due 2018	30,600	30,600
4.10% Senior Notes due 2022	1,000,000	0
Unamortized discount	(1,220)	0
Total long-term debt	1,669,380	1,342,100
Total debt	$           1,670,580	$           1,343,300