Quarterly report pursuant to Section 13 or 15(d)

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

v3.8.0.1
Debt and Secured Revolving Line of Credit (Convertible Debt) (Details) - 2.125% Convertible Senior Notes Due 2026 [Member] - USD ($)
Sep. 30, 2017
Dec. 31, 2016
Sep. 28, 2016
Sep. 14, 2016
Debt Instrument [Line Items]        
Principal $ 805,000,000 $ 805,000,000 $ 105,000,000 $ 700,000,000
Unamortized debt discount (291,000,000) (308,000,000)    
Unamortized debt issuance costs (13,000,000) (14,000,000)    
Net carrying amount 501,000,000 483,000,000    
Carrying amount of the equity component $ 305,000,000 305,000,000    
Equity issuance costs   $ 9,000,000