Debt (Principal Payments Of Debt) (Details) (USD $)	3 Months Ended
	Mar. 31, 2012
Debt Instrument [Line Items]
2012 remaining	$ 460,652,000
2013	315,211,000
2014	473,968,000
2015	243,790,000
2016	231,661,000
2017	142,096,000
2018	64,441,000
2019	153,724,000
2020	3,746,000
2021	2,763,000
Thereafter	118,575,000	[1]
Total	2,210,627,000
3.95 % Convertible Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Convertible senior unsecured notes	$ 54,100,000
Debt instrument stated interest percentage	3.95%
Debt maturity date	2026

[1] Includes $54.1 million of our 3.95% convertible senior unsecured notes outstanding due 2026, which may be called by us at any time and have future put options in 2016 and 2021.