Other Financial Statement Disclosures (Tables)

6 Months Ended

Jun. 30, 2013

Other Financial Statement Disclosures [Abstract]

Estimated Fair Values and Related Carrying Values of Long-Term Debt Securities

Estimated fair values and related carrying values of our long-term debt securities are shown below (in thousands):

	June 30, 2013				December 31, 2012
	Fair value		Carrying value		Fair value		Carrying value
5% Senior Notes, due 2017	$	431,076	$	398,818	$	445,568	$	398,678
7.875% Senior Notes, due 2019	600,063		498,005		617,076		497,842
4.875% Senior Notes, due 2022	719,252		713,998		761,509		714,775
5.4% Senior Notes, due 2042	358,411		398,331		406,493		398,303
	$	2,108,802	$	2,009,152	$	2,230,646	$	2,009,598