v2.4.0.6
Derivative Instruments and Hedging Activities Effect of Derivative Instruments on Statement of Income and Comprehenive Income (Details) (Interest Rate Swap, Cash Flow Hedging Relationships, USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Derivative Instruments, Gain (Loss)      
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion) $ (36,120) $ (12,146) $ (24,230)
Interest Expense
     
Derivative Instruments, Gain (Loss)      
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion) $ (23,414) $ (28,696) $ (54,334)