Debt (Principal Payments Of Debt) (Details) (USD $)	1 Months Ended				6 Months Ended
	May 31, 2012	Aug. 29, 2011	Jun. 30, 2012		Jun. 30, 2012 8.1% Senior Unsecured Notes [Member]	Jun. 30, 2012 3.95% Convertible Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
2012 remaining			$ 103,354,000
2013			315,056,000
2014			473,804,000
2015			239,346,000
2016			231,661,000
2017			142,096,000
2018			64,441,000
2019			153,724,000	[1]
2020			3,746,000
2021			2,763,000
Thereafter			118,575,000	[2]
Total			1,848,566,000
Senior unsecured notes					100,000,000
Convertible senior unsecured notes						$ 54,100,000
Debt instrument stated interest percentage	5.30%				8.10%	3.95%
Debt maturity date	May 2012	May 31, 2012			2019	2026
Debt redemption date					September 2014
Debt put date, earliest date						2016
Debt put date, latest date						2021

[1] Includes $100.0 million of our 8.1% senior unsecured notes due 2019 which may be redeemed by us at any time on or after September 2014 at our option.

[2] 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.