Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		5 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to AMR Class A common stockholders	$ 2,245	$ (6,600)	$ (19,930)	$ (6,162)
Net loss attributable to AMR Class A common stockholders after assumed redemption	$ 9,354	$ (16,066)	$ (36,490)	$ 326
Weighted average Class A common shares outstanding (Basic) (in shares)	180,742,049	173,345,982	171,908,486	180,505,318
Weighted average common shares outstanding (Diluted) (in shares)	180,742,049	207,965,929	208,112,707	180,505,318
Common Class A
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net loss attributable to AMR Class A common stockholders	$ 2,245	$ (6,600)	$ (19,930)	$ (6,162)
Net loss attributable to noncontrolling interests assumed to be redeemed for Class A Common Stock, net of tax	0	(2,157)	(4,914)	0
Net loss attributable to AMR Class A common stockholders after assumed redemption	$ 2,245	$ (8,757)	$ (24,844)	$ (6,162)
Weighted average Class A common shares outstanding (Basic) (in shares)	180,742,049	173,345,982	171,908,486	180,505,318
Class A shares assumed issued to holders of noncontrolling interests upon redemption (in shares)	0	34,619,947	36,204,221	0
Weighted average common shares outstanding (Diluted) (in shares)	180,742,049	207,965,929	208,112,707	180,505,318
Income (loss) per common share attributable to AMR common stockholders:
Basic (in USD per share)	$ 0.01	$ (0.04)	$ (0.12)	$ (0.03)
Diluted (in USD per share)	$ 0.01	$ (0.04)	$ (0.12)	$ (0.03)