Stockholders' Equity (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2015
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Par Value Per Share	$ 1.00	$ 1.00
Preferred Stock, Shares Issued	104,574
Preferred Stock, Liquidation Preference Per Share	$ 1,000
Preferred stock	$ 4,600,000
Preferred Stock, Dividend Rate, Percentage	7.50%
Common Stock, Shares, Issued	12,109,389
Conversion of Stock, Shares Converted	398,262	288,620
Common Stock, Capital Shares Reserved for Future Issuance	374,478				1,200,000
Preferred stock dividend condition - minimum net income preceding quarter	$ 7,500,000
Preferred stock dividend condition - minimum free cash flow preceding four quarters	35,000,000
Preferred stock dividend condition - minimum cash balance preceding quarter	150,000,000
Preferred Stock, Liquidation Preference, Value	53,900,000	$ 127,200,000
Preferred Stock, Cumulative Undeclared Dividend	$ 12,100,000	22,600,000
Operating Loss Carryforwards				$ 749,200,000
Common Stock Ownership Enabling Preferred Stock Purchase Rights	4.99%
Common Stock Ownership Enabling Preferred Stock Purchase Rights, Incremental	0.50%
Stock issued during period	$ 23,100,000
Payments for Repurchase of Preferred Stock and Preference Stock	$ 61,600,000	$ 0
Preferred Stock, Shares Outstanding	41,720	104,574	104,574
Common Class A [Member]
Class of Stock [Line Items]
Common Stock, Shares Authorized	70,000,000	70,000,000
Common Stock, Par or Stated Value Per Share	$ 0.10	$ 0.10
Common Stock, Shares, Issued	11,390,189	8,347,427
Stock Issued During Period, Shares, New Issues	2,537,500	20,000
Conversion of Stock, Shares Converted	398,262	288,620
Sale of Stock, Price Per Share	$ 10.00
Gross Proceeds from Issuance of Common Stock	$ 25,400,000
Payments of Stock Issuance Costs	$ 2,300,000
Common Class B [Member]
Class of Stock [Line Items]
Common Stock, Shares Authorized	30,000,000	30,000,000
Common Stock, Par or Stated Value Per Share	$ 0.10	$ 0.10
Common Stock, Shares, Issued	719,200	1,117,462
Conversion of Stock, Shares Converted	(398,262)	(288,620)
Preferred Series B [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Issued	41,720	104,574
Preferred Stock, Liquidation Preference Per Share	$ 1,000.00
Preferred stock	$ 100,000	$ 4,600,000
Preferred Stock, Dividend Rate, Percentage	7.50%
Preferred Stock, Liquidation Preference, Value	$ 53,900,000	$ 127,200,000
Stock Repurchased and Retired During Period, Shares	62,854
Stock Repurchase Price per Share	$ 954.59
Payments for Repurchase of Preferred Stock and Preference Stock	60,000,000
Preferred Stock, Liquidation Amount per Share	$ 1,272.78
Preferred Stock, Shares Outstanding	41,720