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

Debt (Revolving credit facilities) (Details)

v3.8.0.1
Debt (Revolving credit facilities) (Details) - USD ($)
1 Months Ended 12 Months Ended
Dec. 16, 2013
Feb. 28, 2017
Mar. 31, 2014
Dec. 31, 2017
Feb. 28, 2018
Sep. 30, 2017
Oct. 31, 2016
Dec. 31, 2015
Jun. 30, 2015
Asia Revolving Credit Facility [Member]                  
Debt Instrument [Line Items]                  
Credit facility maximum borrowing capacity             $ 600,000,000.0 $ 575,000,000.0  
Debt instrument term       5 years          
Asia Revolving Credit Facility [Member] | Revolving Period [Member]                  
Debt Instrument [Line Items]                  
Debt instrument term       3 years          
Spread over reference rate       1.95%          
Asia Revolving Credit Facility [Member] | Term Out Period [Member]                  
Debt Instrument [Line Items]                  
Debt instrument term       2 years          
Credit facility, percentage of balance to be repaid in December 2019       66.67%          
Credit facility, percentage of balance to be repaid in December 2020       33.33%          
Asia Revolving Credit Facility [Member] | Term Out Period [Member] | Interest Rate During First Year [Member]                  
Debt Instrument [Line Items]                  
Spread over reference rate       2.25%          
Asia Revolving Credit Facility [Member] | Term Out Period [Member] | Interest Rate During Second Year [Member]                  
Debt Instrument [Line Items]                  
Spread over reference rate       2.50%          
Citi Revolving Credit Facility [Member]                  
Debt Instrument [Line Items]                  
Credit facility maximum borrowing capacity   $ 3,750,000,000.00 $ 2,750,000,000.00     $ 3,895,000,000.000      
Debt instrument term     4 years            
Spread over reference rate   1.50% 2.00%            
Credit facility, maximum size of accordion feature     $ 4,000,000,000            
Citi Revolving Credit Facility [Member] | Subsequent Event [Member]                  
Debt Instrument [Line Items]                  
Credit facility maximum borrowing capacity         $ 4,000,000,000.0        
AIG Revolving Credit Facility [Member]                  
Debt Instrument [Line Items]                  
Credit facility maximum borrowing capacity $ 1,000,000,000.0     $ 200,000,000         $ 500,000,000.0
Debt instrument term 5 years                
AIG Revolving Credit Facility [Member] | Interest Rate Option1 [Member]                  
Debt Instrument [Line Items]                  
Spread over reference rate       3.75%          
AIG Revolving Credit Facility [Member] | Interest Rate Option2 [Member]                  
Debt Instrument [Line Items]                  
Stated interest rate       2.75%          
AIG Revolving Credit Facility [Member] | Interest Rate Option2 X [Member]                  
Debt Instrument [Line Items]                  
Spread over reference rate       0.50%          
AIG Revolving Credit Facility [Member] | Interest Rate Option2 Z [Member]                  
Debt Instrument [Line Items]                  
Spread over reference rate       1.00%