Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt (Narrative) (Details)

 v2.3.0.11
Long-Term Debt (Narrative) (Details) (USD $)
5 Months Ended 6 Months Ended
Jun. 05, 2011
Jun. 30, 2011
Dec. 31, 2010
Jun. 30, 2011
Tranche A Notes [Member]
Jun. 30, 2011
Tranche B Notes [Member]
Jun. 30, 2011
Letter of Credit [Member]
Dec. 31, 2010
Letter of Credit [Member]
Jun. 30, 2011
Sweep Program [Member]
Aug. 10, 2011
Five Year Senior Unsecured Revolving Credit Facility [Member]
Notes issued   $ 262,900,000              
Periodic principal payments   35,700,000              
Fixed interest rate, minimum   4.00              
Fixed interest rate, maximum   5.85              
Effective average interest rate   5.13% 5.54%            
Senior notes, noncurrent   95,000,000   50,000,000 45,000,000        
Fixed interest rate       4.00% 4.79%        
Maximum borrowing capacity   300,000,000       150,000,000   15,000,000 200,000,000
Current borrowing capacity   225,000,000              
Minimum increments under the additional borrowings   25,000,000              
Credit facility interest   At our option, revolving loans under the facility bear interest at either: (a) the higher of Wells Fargo's prime rate or the federal funds rate plus 0.5% per annum; (b) LIBOR (one, two, three or six months) plus an applicable margin; or (c) one-month LIBOR plus an applicable margin ("LIBOR Index Rate").              
Applicable margin interest on credit facility, low end   0.50%              
Applicable margin interest on credit facility, high end   1.125%              
Margin interest during period 0.625%                
Decreases in marginal interest during period   0.50%              
Line of credit, outstanding   $ 0 $ 66,230,000     $ 50,800,000 $ 49,600,000