Redeemable Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Jun. 30, 2015	Mar. 31, 2020	Dec. 31, 2019
Stockholders' Equity [Abstract]
Preferred stock, issued	363,000	363,000	363,000
Gross proceeds from issuance of Series A Preferred Stock	$ 363
Preferred stock, stated value	$ 1,000
Preferred stock, dividend rate	6.50%	6.50%	6.50%
Percent of par value	105.00%
Preferred stock, initial conversion rate	55.9284
Preferred stock, initial conversion price	$ 17.88
Preferred stock, common stock as percentage of conversion price	150.00%