XML 19 R55.htm IDEA: XBRL DOCUMENT v2.4.0.6
Line of Credit and Capital Lease Obligations (Narrative) (Detail) (USD $)
 12 Months Ended
Dec. 31, 2012
Nov. 19, 2012
Line Of Credit Facility Covenant Compliance [Line Items]    
Line of Credit facility, borrowing capacity $ 800,000,000 $ 500,000,000
Line of Credit facility, maturity date Nov. 17, 2017  
Line of Credit facility, estimated increase in borrowings 1,000,000,000  
Line of Credit facility, outstanding principal balance 144,000,000  
Line of Credit facility, reduction in the available balance 5,500,000  
Letters of credit, weighted average interest rate 1.30%  
Line of Credit facility, available balance 650,500,000  
Letter of Credit [Member]
    
Line Of Credit Facility Covenant Compliance [Line Items]    
Line of Credit facility, borrowing capacity 75,000,000  
Swingline Loans [Member]
    
Line Of Credit Facility Covenant Compliance [Line Items]    
Line of Credit facility, borrowing capacity $ 37,500,000  
Federal Funds Rate [Member]
    
Line Of Credit Facility Covenant Compliance [Line Items]    
Debt instrument, interest rate 0.50%  
Libor [Member] | Maximum [Member]
    
Line Of Credit Facility Covenant Compliance [Line Items]    
Debt instrument, interest rate, as defined in the Line of Credit 1.00%  
Libor [Member] | Maximum [Member] | Applicable Margin Rate [Member]
    
Line Of Credit Facility Covenant Compliance [Line Items]    
Debt instrument, interest rate, as defined in the Line of Credit 0.75%  
Libor [Member] | Maximum [Member] | Alternate Base Rate [Member]
    
Line Of Credit Facility Covenant Compliance [Line Items]    
Debt instrument, interest rate, as defined in the Line of Credit 1.75%  
Libor [Member] | Minimum [Member] | Applicable Margin Rate [Member]
    
Line Of Credit Facility Covenant Compliance [Line Items]    
Debt instrument, interest rate, as defined in the Line of Credit 0.125%  
Libor [Member] | Minimum [Member] | Alternate Base Rate [Member]
    
Line Of Credit Facility Covenant Compliance [Line Items]    
Debt instrument, interest rate, as defined in the Line of Credit 1.125%