Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Debt (Senior secured notes) (Details)

v3.8.0.1
Debt (Senior secured notes) (Details)
12 Months Ended
Dec. 31, 2017
subsidiary
Aug. 20, 2010
USD ($)
Debt Instrument [Line Items]    
Number of subsidiaries that have guaranteed the debt | subsidiary 2  
Senior Secured Notes [Member]    
Debt Instrument [Line Items]    
Face amount   $ 3,900,000,000.0
Prepayment penalty percentage 1.00%  
Spread over reference rate 0.50%  
6.5% Senior Secured Bonds, Due September 2014 [Member]    
Debt Instrument [Line Items]    
Face amount   $ 1,350,000,000.00
Stated interest rate   6.50%
6.75% Senior Secured Bonds, Due September 2016 [Member]    
Debt Instrument [Line Items]    
Face amount   $ 1,275,000,000.000
Stated interest rate   6.75%
7.125% Senior Secured Bonds, Due September 2018 [Member]    
Debt Instrument [Line Items]    
Face amount   $ 1,275,000,000.000
Stated interest rate   7.125%