Quarterly report pursuant to Section 13 or 15(d)

Senior Unsecured Notes (Summary Of Senior Unsecured Notes) (Details)

v2.4.0.6
Senior Unsecured Notes (Summary Of Senior Unsecured Notes) (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Mar. 31, 2012
Dec. 31, 2011
Long-Term Debt [Line Items]    
Senior Unsecured Notes $ 1,019,435 $ 1,119,267
5.250% Senior Unsecured Notes, Due January 15, 2012 [Member]
    
Long-Term Debt [Line Items]    
Senior Unsecured Notes   99,988 [1]
Effective Rate 5.457% [1],[2]  
Interest rate of Senior Unsecured Notes 5.25% [1]  
Maturity date of the Senior Unsecured Notes Jan. 15, 2012 [1]  
6.150% Senior Unsecured Notes, Due December 15, 2012 [Member]
    
Long-Term Debt [Line Items]    
Senior Unsecured Notes 94,561 [3] 94,438 [3]
Effective Rate 6.894% [2],[3]  
Interest rate of Senior Unsecured Notes 6.15% [3]  
Maturity date of the Senior Unsecured Notes Dec. 15, 2012 [3]  
5.820% Senior Unsecured Notes, Due March 15, 2013 [Member]
    
Long-Term Debt [Line Items]    
Senior Unsecured Notes 26,000 [3] 25,972 [3]
Effective Rate 6.448% [2],[3]  
Interest rate of Senior Unsecured Notes 5.82% [3]  
Maturity date of the Senior Unsecured Notes Mar. 15, 2013 [3]  
4.600% Senior Unsecured Notes, Due June 15, 2013 [Member]
    
Long-Term Debt [Line Items]    
Senior Unsecured Notes 99,965 99,958
Effective Rate 4.742% [2]  
Interest rate of Senior Unsecured Notes 4.60%  
Maturity date of the Senior Unsecured Notes Jun. 15, 2013  
5.125% Senior Unsecured Notes, Due February 15, 2014 [Member]
    
Long-Term Debt [Line Items]    
Senior Unsecured Notes 200,450 200,509
Effective Rate 5.11% [2]  
Interest rate of Senior Unsecured Notes 5.125%  
Maturity date of the Senior Unsecured Notes Feb. 15, 2014  
5.125% Senior Unsecured Notes, Due January 15, 2015 [Member]
    
Long-Term Debt [Line Items]    
Senior Unsecured Notes 149,740 149,717
Effective Rate 5.297% [2]  
Interest rate of Senior Unsecured Notes 5.125%  
Maturity date of the Senior Unsecured Notes Jan. 15, 2015  
5.800% Senior Unsecured Notes, Due January 15, 2016 [Member]
    
Long-Term Debt [Line Items]    
Senior Unsecured Notes 200,294 200,313
Effective Rate 5.806% [2]  
Interest rate of Senior Unsecured Notes 5.80%  
Maturity date of the Senior Unsecured Notes Jan. 15, 2016  
7.750% Senior Unsecured Notes, Due August 15, 2019 [Member]
    
Long-Term Debt [Line Items]    
Senior Unsecured Notes $ 248,425 $ 248,372
Effective Rate 8.017% [2]  
Interest rate of Senior Unsecured Notes 7.75%  
Maturity date of the Senior Unsecured Notes Aug. 15, 2019  
[1] These notes were paid at maturity, primarily from borrowing on the Company's unsecured revolving credit facility.
[2] Includes the cost of terminated treasury lock agreements (if any), offering and other transaction costs and the discount/premium on the notes, as applicable.
[3] On April 25, 2012, the Company gave notice that it will redeem these notes on May 25, 2012 using cash on hand and borrowings from its unsecured revolving credit facility.