Annual report pursuant to Section 13 and 15(d)

Interest Rate Swap Agreements (Details)

v2.4.0.6
Interest Rate Swap Agreements (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Agreement
Dec. 31, 2010
Dec. 31, 2009
Interest rate swap agreements designated as hedge agreements      
Amount Designated as a Hedge $ 620,615    
Current Liability 9,979    
Long-Term Liability 6,597    
Estimated Total Fair Value at December 31, 2011 16,576    
Interest Rate Swap Agreements (Additional) (Textual) [Abstract]      
Number of interest rate swap agreements 5    
Changes in fair values are reclassified from accumulated other comprehensive income (loss) into earnings 15,929 11,771 10,395
Number of swap agreements used for hedging interest payments 2    
Agreements reclassified as component of loss on early retirement of debt 2,760    
Amortized Interest Expenses related to a previously terminated interest rate swap agreement 4,236 4,633 4,633
Losses accumulated in other comprehensive income related to a previously terminated interest rate swap agreement 18,147    
Interest expense on Interest rate swap agreement will amortize over the next twelve months 3,953    
Interest Rate Swap One Agreement [Member]
     
Interest rate swap agreements designated as hedge agreements      
Amount Designated as a Hedge 106,632    
Nominal Amount of Interest Rate Swap 125,000    
Effective Date Aug. 01, 2007    
Pay Rate 4.922%    
Receive Rate 3-Month LIBOR    
Expiration Date Aug. 12, 2012    
Current Liability 3,375    
Long-Term Liability 0    
Estimated Total Fair Value at December 31, 2011 3,375    
Interest Rate Swap Agreements (Textual) [Abstract]      
Nominal Amount of Interest Rate Swap 125,000    
Interest Rate Swap One Agreement [Member] | Nondesignated [Member]
     
Interest Rate Swap Agreements (Textual) [Abstract]      
Portion of interest rate swap not designated as hedge 18,368    
Interest Rate Swap Two Agreement [Member]
     
Interest rate swap agreements designated as hedge agreements      
Amount Designated as a Hedge 63,983    
Nominal Amount of Interest Rate Swap 75,000    
Effective Date Nov. 01, 2008    
Pay Rate 3.63%    
Receive Rate 1-Month LIBOR    
Expiration Date Nov. 01, 2012    
Current Liability 2,124    
Long-Term Liability 0    
Estimated Total Fair Value at December 31, 2011 2,124    
Interest Rate Swap Agreements (Textual) [Abstract]      
Nominal Amount of Interest Rate Swap 75,000    
Interest Rate Swap Two Agreement [Member] | Nondesignated [Member]
     
Interest Rate Swap Agreements (Textual) [Abstract]      
Portion of interest rate swap not designated as hedge 11,017    
Interest Rate Swap Three Agreement [Member]
     
Interest rate swap agreements designated as hedge agreements      
Nominal Amount of Interest Rate Swap 175,000    
Effective Date Dec. 01, 2010    
Pay Rate 1.3975%    
Receive Rate 1-Month LIBOR    
Expiration Date Sep. 01, 2015    
Current Liability 1,605    
Long-Term Liability 2,228    
Estimated Total Fair Value at December 31, 2011 3,833    
Interest Rate Swap Agreements (Textual) [Abstract]      
Nominal Amount of Interest Rate Swap 175,000    
Interest Rate Swap Four Agreement [Member]
     
Interest rate swap agreements designated as hedge agreements      
Nominal Amount of Interest Rate Swap 175,000    
Effective Date Dec. 01, 2010    
Pay Rate 1.40%    
Receive Rate 1-Month LIBOR    
Expiration Date Sep. 01, 2015    
Current Liability 1,632    
Long-Term Liability 2,271    
Estimated Total Fair Value at December 31, 2011 3,903    
Interest Rate Swap Agreements (Textual) [Abstract]      
Nominal Amount of Interest Rate Swap 175,000    
Interest Rate Swap Five Agreement [Member]
     
Interest rate swap agreements designated as hedge agreements      
Nominal Amount of Interest Rate Swap 100,000    
Effective Date Nov. 01, 2011    
Pay Rate 1.715%    
Receive Rate 1-Month LIBOR    
Expiration Date Apr. 01, 2016    
Current Liability 1,243    
Long-Term Liability 2,098    
Estimated Total Fair Value at December 31, 2011 3,341    
Interest Rate Swap Agreements (Textual) [Abstract]      
Nominal Amount of Interest Rate Swap $ 100,000