Background and Business Description AMPS Exchange (Details) - USD ($)	Aug. 03, 2018	Jun. 30, 2018	Jun. 22, 2018	Dec. 31, 2017	May 01, 2013
AMPS Exchange Supporting Holder Percent of Total Outstanding			89.00%
AMPS Exchange Supporting Holder Minimum Tender Commitment			80.00%
Successor [Member]
Preferred Stock, Shares Outstanding		0		0
Stockholders' Equity Attributable to Noncontrolling Interest		$ 264,110,000		$ 264,110,000
Warrants issued exercise price					$ 16.67
Ambac Assurance Corporation [Member]
Preferred Stock, Shares Outstanding				26,411
Preferred Stock, Liquidation Preference, Value				$ 660,275,000
Subsequent Event [Member]
AMPS Exchange Surplus Notes Issued Per Share	$ 13,875
AMPS Exchange Shares Tendered	22,096
AMPS Exchange Cash Paid Per Share	$ 500
AMPS Exchange Warrants Issued Per Share	37.3076
AMPS Exchange Percent Acquired	84.40%
AMPS Exchange Shares Acquired	22,296
AMPS Exchange Aggregate Liquidation Preference	$ 557,400,000
AMPS Exchange Total Surplus Notes Issued	212,740,000
AMPS Exchange Interest Included in Surplus Notes Issued	96,617,000
AMPS Exchange Total Cash Paid	$ 11,048,000
AMPS Exchange Total Warrants Issued	824,307
AMPS Exchange Nominal Discount	$ 227,000,000
AMPS Exchange Nominal Discount at Fair Value	252,000,000
AMPS Exchange Expected Loss Based on Carry Value	83,000,000
AMPS Liquidation Preference Value Per Share	25,000
Subsequent Event [Member] | Successor [Member]
Stockholders' Equity Attributable to Noncontrolling Interest	41,150,000
Subsequent Event [Member] | Afg [Member]
AMPS Exchange Aggregate Liquidation Preference	$ 34,650,000