Quarterly report pursuant to Section 13 or 15(d)

Debt and Secured Revolving Line of Credit (Narrative) (Details)

v3.19.1
Debt and Secured Revolving Line of Credit (Narrative) (Details)
1 Months Ended 3 Months Ended
Sep. 30, 2016
USD ($)
day
Mar. 30, 2019
USD ($)
$ / shares
Mar. 31, 2018
USD ($)
Mar. 29, 2019
$ / shares
Dec. 29, 2018
USD ($)
Jun. 16, 2014
USD ($)
Feb. 26, 2014
USD ($)
Aug. 15, 2012
USD ($)
Debt Instrument [Line Items]                
Aggregate principal amount repurchased   $ 164,000,000 $ 14,000,000          
Loss on debt redemption   8,000,000 $ 1,000,000          
Secured Revolving Line of Credit                
Debt Instrument [Line Items]                
Secured revolving line of credit, outstanding balance   $ 70,000,000     $ 70,000,000      
Secured revolving line of credit, interest rate   6.00%     6.00%      
Letters of credit outstanding, amount   $ 26,000,000            
Secured revolving line of credit, remaining borrowing capacity (up to)   $ 119,000,000            
Repayment period   90 days            
Secured Revolving Line of Credit | Amended and restated loan and security agreement                
Debt Instrument [Line Items]                
Maximum borrowing capacity   $ 500,000,000            
Maximum letters of credit available for issuance   45,000,000            
Aggregate amount by which size of commitments may be increased (up to)   $ 200,000,000            
Secured Revolving Line of Credit | Amended and restated loan and security agreement | Federal Funds Rate                
Debt Instrument [Line Items]                
Basis spread on variable rate   0.50%            
Secured Revolving Line of Credit | Amended and restated loan and security agreement | LIBOR                
Debt Instrument [Line Items]                
Basis spread on variable rate   1.00%            
2.125% Convertible Senior Notes due 2026                
Debt Instrument [Line Items]                
Stated interest rate 2.125%              
Principal amount $ 805,000,000 $ 805,000,000     $ 805,000,000      
Outstanding aggregate principal amount   $ 805,000,000            
Conversion price (in dollars per share) | $ / shares   $ 8.00            
Remaining life   90 months            
Share price (in usd per share) | $ / shares       $ 25.52        
If-converted value in excess of principal   $ 1,763,000,000            
Effective interest rate   8.00%            
2.125% Convertible Senior Notes due 2026 | Debt Instrument, circumstance 1                
Debt Instrument [Line Items]                
Threshold trading days | day 20              
Threshold consecutive trading days | day 30              
Threshold percentage of conversion price 130.00%              
2.125% Convertible Senior Notes due 2026 | Debt Instrument, circumstance 2                
Debt Instrument [Line Items]                
Threshold consecutive trading days | day 10              
Threshold percentage of conversion price 98.00%              
Conversion period after threshold period days | day 5              
6.75% Senior Notes due 2019                
Debt Instrument [Line Items]                
Stated interest rate             6.75%  
Principal amount             $ 600,000,000  
Aggregate principal amount repurchased   $ 66,000,000            
7.50% Senior Notes due 2022                
Debt Instrument [Line Items]                
Stated interest rate               7.50%
Principal amount               $ 500,000,000
Outstanding aggregate principal amount   312,000,000            
Aggregate principal amount settled   25,000,000            
7.00% Senior Notes due 2024                
Debt Instrument [Line Items]                
Stated interest rate           7.00%    
Principal amount           $ 500,000,000    
Outstanding aggregate principal amount   176,000,000            
Aggregate principal amount repurchased   $ 74,000,000