Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, shares in Millions		12 Months Ended
	May 05, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 23, 2019
Class of Stock [Line Items]
Common stock, shares authorized (in shares)		1,125.0	1,125.0
Common stock, par value (in dollars per share)		$ 0.20	$ 0.20
Common stock shares outstanding (in shares)		436.0
Common shares unissued but encumbered (in shares)		41.0
Common stock dividends		$ 0	$ 0	$ 0
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock shares outstanding (in shares)	3.3
Preferred stock dividend rate (as a percentage)		6.97%
Preferred stock dividend rate (in dollars per share)	$ 50
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock shares outstanding (in shares)		4.0	4.0
Preferred stock liquidation preference (in dollars per share)		$ 100
Common Stock
Class of Stock [Line Items]
Share price (in dollars per share)		$ 8.31
Three Month LIBOR | Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock dividend rate (as a percentage)		1.70%
Subsequent Event
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 200,000,000