Other Financial Statement Disclosures (Estimated Fair Values and Related Carrying Values of Long-term Debt Securities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Fair value [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	$ 2,950,550	$ 2,117,474
Fair value [Member] | Senior Notes due 2017 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	431,153	433,879
Fair value [Member] | Senior Notes Due 2019 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	603,258	603,177
Fair value [Member] | Senior Notes due 2022 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	731,136	711,816
Fair value [Member] | Senior Notes due 2024 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	406,284	0
Fair value [Member] | Senior Notes Due 2042 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	378,314	368,602
Fair value [Member] | Senior Notes due 2044 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	400,405	0
Carrying value [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	2,807,540	2,008,700
Carrying value [Member] | Senior Notes due 2017 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	399,173	398,961
Carrying value [Member] | Senior Notes Due 2019 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	498,418	498,171
Carrying value [Member] | Senior Notes due 2022 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	712,035	713,208
Carrying value [Member] | Senior Notes due 2024 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	399,621	0
Carrying value [Member] | Senior Notes Due 2042 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	398,402	398,360
Carrying value [Member] | Senior Notes due 2044 [Member]
Fair values of Financial Instruments [Abstract]
Notes notes	$ 399,891	$ 0