Senior Notes And Other Debt (Schedule of Debt) (Details) (USD $)	Dec. 31, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Face Value	$ 1,884,298,000
Total debt, carrying value	1,871,535,000		1,500,503,000
Senior Notes due February 15, 2013 [Member]
Debt Instrument [Line Items]
Face Value	200,000,000
Carrying Value	199,959,000		199,627,000
Rate	5.875%
Senior Notes due May 15, 2015 [Member]
Debt Instrument [Line Items]
Face Value	200,000,000
Carrying Value	199,559,000		199,373,000
Rate	5.60%
Senior Notes due August 15, 2019 [Member]
Debt Instrument [Line Items]
Face Value	150,000,000
Carrying Value	149,057,000		148,914,000
Rate	6.15%
Senior Notes due September 15, 2019 [Member]
Debt Instrument [Line Items]
Face Value	300,000,000
Carrying Value	298,292,000		298,038,000
Rate	7.375%
Senior Notes due September 15, 2020 [Member]
Debt Instrument [Line Items]
Face Value	300,000,000
Carrying Value	297,401,000		297,065,000
Rate	5.375%
Senior Notes due January 1, 2022 [Member]
Debt Instrument [Line Items]
Face Value	76,503,000
Carrying Value	75,962,000		75,924,000
Rate	8.70%
Senior Notes due March 15, 2022 [Member]
Debt Instrument [Line Items]
Face Value	350,000,000
Carrying Value	346,163,000		0
Rate	4.625%
Senior Notes due February 15, 2037 [Member]
Debt Instrument [Line Items]
Face Value	250,000,000
Carrying Value	247,347,000		247,236,000
Rate	6.25%
Subsidiary Debt [Member]
Debt Instrument [Line Items]
Face Value	57,795,000	[1]
Carrying Value	$ 57,795,000	[1]	$ 34,326,000	[1]

[1] Subsidiary debt is due as follows: $17 million in 2013, $39 million in 2014, $1 million in 2015 and $1 million thereafter.