Capitalization (Details) - USD ($)		1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 22, 2018	Jan. 31, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Dividends declared (in usd per share)			$ 0.38	$ 0.72
Proceeds from issuance of equity	$ 2,500,000,000
Par Value, in dollars per share	$ 100		100		$ 100
Amount of private placement shares	30,120,482
Common stock, par value (in dollars per share)	$ 0.10		$ 0.1		$ 0.1
Amount of private placement	$ 850,000,000
Liquidation preference value	$ 1,000
Conversion price (in dollars per share)	$ 27.42
Preferred stock shares outstanding		209,822
Conversion threshold of Preferred Stock (in shares)	323,200
Number of shares to be converted within two years	0
Common stock share cap (in shares)	58,964,222
Amortization of beneficial conversion			$ 0	$ 113,000,000
Preferred Stock
Class of Stock [Line Items]
Number of shares converted (in shares)		494,767			911,411
OPIC
Class of Stock [Line Items]
Amount of private placement	$ 847,000,000
Common Stock
Class of Stock [Line Items]
Amount of private placement	$ 3,000,000
Number of shares issued (in shares)		18,044,018			33,238,910
Series A Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock shares issued	1,616,000		1,616,000		1,616,000
Amount of preferred stock investment	$ 1,620,000,000
Preferred stock shares outstanding			209,822		704,589
Series A Convertible Preferred Stock | Preferred Stock
Class of Stock [Line Items]
Amount of preferred stock investment	162,000,000
Series A Convertible Preferred Stock | OPIC
Class of Stock [Line Items]
Amount of preferred stock investment	$ 1,460,000,000