Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands					2 Months Ended	3 Months Ended		4 Months Ended	12 Months Ended
	Feb. 26, 2019	Dec. 27, 2018	Nov. 08, 2018	Apr. 24, 2018	Feb. 26, 2019	Mar. 31, 2019	Mar. 31, 2018	Feb. 26, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Number of shares sold		312,065				54,750
Proceeds retained (in excess of)	$ 30,000
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs						$ 11,985
Common stock issuance costs						10,514	$ 0		$ (1,500)
PreferredStockFairValue									$ 402,884
Common Stock
Class of Stock [Line Items]
Proceeds from issuance of stock	$ 450,000
Number of shares sold	36,000,000				7,000,000
Subscription price (in dollars per share)	$ 12.50				$ 12.50			$ 12.50
Series B Preferred Stock
Class of Stock [Line Items]
Shares Issued, Price Per Share									$ 1,000
Preferred Stock, Shares Issued									155,000
Preferred Stock, Redemption Term									8 years
Preferred Stock, Shares Outstanding									155,000
Preferred Stock, Dividend Rate, Percentage									17.78%
PreferredStockFairValue									$ 205,972
Series C Preferred Stock
Class of Stock [Line Items]
Shares Issued, Price Per Share									$ 1,000
Preferred Stock, Shares Issued									55,000
Preferred Stock, Redemption Term									8 years
Preferred Stock, Shares Outstanding									55,000
Preferred Stock, Dividend Rate, Percentage									17.78%
PreferredStockFairValue									$ 102,098
Series D Preferred Stock
Class of Stock [Line Items]
Shares Issued, Price Per Share									$ 1.00
Preferred Stock, Shares Issued									100
Preferred Stock, Redemption Term									8 years
Preferred Stock, Shares Outstanding									100
PreferredStockFairValue									$ 900
Series E Preferred Stock
Class of Stock [Line Items]
Shares Issued, Price Per Share									$ 1,000
Preferred Stock, Shares Issued									90,000
Preferred Stock, Redemption Term									6 years
Preferred Stock, Shares Outstanding									37,500
Preferred Stock, Dividend Rate, Percentage									16.03%
PreferredStockFairValue									$ 47,367
Series E-1 Preferred Stock
Class of Stock [Line Items]
Proceeds from issuance of stock						$ 17,500
Number of shares sold						17,500
Shares Issued, Price Per Share						$ 1,000
Preferred Stock, Shares Issued									35,728
Preferred Stock, Redemption Term									6 years
Payments of Stock Issuance Costs							1,100
Preferred Stock, Shares Outstanding									35,728
Preferred Stock, Dividend Rate, Percentage									16.03%
PreferredStockFairValue									$ 46,547
Series E-1 Preferred Stock Tranche 2
Class of Stock [Line Items]
Number of shares sold						18,228
Shares Issued, Price Per Share						$ 960
Series E-1 Preferred Stock Tranche 3
Class of Stock [Line Items]
Number of shares sold						19,022
Shares Issued, Price Per Share						$ 920
E-1FirstTranche [Member] | Series E-1 Preferred Stock
Class of Stock [Line Items]
Proceeds from issuance of stock				$ 17,500
Preferred Stock, Shares Issued				18,228
Standby Purchase Agreement with Elliott [Member]
Class of Stock [Line Items]
Number of shares sold			29,000,000					34,000,000
Percentage of ownership after rights offering	90.40%
Fair Value, Inputs, Level 3 [Member]
Class of Stock [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)							$ 6,057