v3.19.3.a.u2
Variable Interest Entities ("VIEs") - Narrative (Details) - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
Jul. 02, 2019
Apr. 30, 2019
Mar. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Variable Interest Entity [Line Items]          
Limited guarantee       $ 50 $ 50
Variable Interest Entity, Primary Beneficiary          
Variable Interest Entity [Line Items]          
Assets       1,200 $ 115
Liabilities       $ 159  
Percentage of ownership before sale of stock   100.00%      
Variable Interest Entity, Not Primary Beneficiary | Event Center Office Partners, LLC          
Variable Interest Entity [Line Items]          
Payments to acquire variable interest entity     $ 136    
Ownership interest     45.00% 45.00% 45.00%
Limited guarantee       $ 50  
Preferred Class A | ATG Investment          
Variable Interest Entity [Line Items]          
Percentage of ownership after sale of stock 13.80%