Background and Business Description AMPS Exchange (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	Aug. 03, 2018 USD ($) $ / shares shares	Jun. 30, 2018 USD ($) shares	May 01, 2013 $ / shares
Preferred Stock, Shares Issued | shares	0	0
Stockholders' Equity Attributable to Noncontrolling Interest	$ 60,000	$ 41,000			$ 264,000
AMPS Liquidation Preference Value Per Share | $ / shares				$ 25,000
AMPS Exchange Surplus Notes Issued Per Share | $ / shares				$ 13,875
AMPS Exchange Shares Tendered | shares				22,096
AMPS Exchange Cash Paid Per Share | $ / shares				$ 500
AMPS Exchange Warrants Issued Per Share | $ / shares				$ 37.3076
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares						$ 16.67
AMPS Exchange Percent Acquired				0.844
AMPS Exchange Shares Acquired | shares				22,296
AMPS Exchange Aggregated Liquidation Preference				$ 557,000
AMPS Exchange Nominal Discount				227,000
AMPS Exchange Nominal Discount at Fair Value				253,000
AMPS Exchange Total Surplus Notes Issued				213,000
AMPS Exchange Interest Included in Surplus Notes Issued				$ 98,000
AMPS Exchange Total Warrants Issued				824,307
AMPS Exchange Cash Paid	0	11,000
AMPS Exchange Loss Based on Carry Value	$ 0	$ 82,000	$ 0
Preferred Stock, Shares Outstanding | shares	0	0
Ambac Assurance Corporation [Member]
Preferred Stock, Shares Issued | shares	1,386
Preferred Stock, Liquidation Preference, Value	$ 138,000	$ 103,000			$ 660,000
Preferred Stock, Shares Outstanding | shares	5,501	4,115			26,411
AFG [Member]
AMPS Exchange Aggregated Liquidation Preference				$ 35,000