Redeemable Preferred Stock (Details)		3 Months Ended			12 Months Ended
	Nov. 30, 1998 shares	Mar. 31, 2018 USD ($) Tranche $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares	Jun. 30, 2006 USD ($)	Dec. 31, 1991 $ / shares shares	Dec. 31, 2017 USD ($)	Apr. 18, 2017 USD ($)	Dec. 31, 1990 shares
Senior Redeemable Preferred Stock [Abstract]
Redeemable preferred stock liquidation value (in dollar per share) | $ / shares			$ 1,000
Senior Redeemable Preferred Stock [Member]
Senior Redeemable Preferred Stock [Abstract]
Redemption amount of senior redeemable preferred stock | $							$ 2,100,000
Undeclared unpaid dividends | $			$ 1,600,000
Accrued dividends reported as interest expenses | $			$ 16,000
Senior Redeemable Preferred Stock [Member] | Toxford [Member]
Senior Redeemable Preferred Stock [Abstract]
Senior redeemable preferred stock maturity date		May 31, 2018
Percentage of redeemable preferred stock held by related party after redemption			76.40%
Public Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock authorized (in shares)		6,000,000
Preferred stock par value (in dollar per share) | $ / shares		$ 0.01
Preferred stock dividend rate per annum		12.00%			6.00%
Dividends Payable | $		$ 100,700,000				$ 99,700,000
Preferred stock issued and outstanding (in shares)		3,185,586
Preferred stock issued (in shares)								2,858,723
12% Cumulative Exchangeable Redeemable Preferred Stock [Abstract]
Adjusted accrued accretion of public preferred stock | $				$ 1,500,000
Number of shares declared as dividend (in shares)					736,863
Number of annual tranches during the period | Tranche		5
Period during which redeemable preferred stock not callable		12 months
Preferred stock dividend rate per annum (in dollars per share) | $ / shares		$ 1.20			$ 0.60
Preferred stock, liquidation preference (in dollars per share) | $ / shares		$ 10
Dividends on preferred stock | $		$ 1,000,000
Redemption of public preferred stock (in shares)	410,000
Series A-1 Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock authorized (in shares)			1,250
Preferred stock par value (in dollar per share) | $ / shares			$ 0.01
Preferred stock dividend rate per annum			14.125%
Series A-1 Preferred Stock [Member] | Senior Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock issued and outstanding (in shares)			197
Series A-2 Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock authorized (in shares)			1,750
Series A-2 Preferred Stock [Member] | Senior Redeemable Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock issued and outstanding (in shares)			276