Background and Business Description Rehabilitation Exit Support Agreement (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Apr. 29, 1991	Dec. 31, 2017	Dec. 31, 2023	Dec. 31, 2022	Apr. 30, 2013
Preferred Stock, Shares Outstanding			0	0
Common stock, shares authorized			130,000,000	130,000,000
Common Stock, Par or Stated Value Per Share					$ 0.01
Preferred stock, shares authorized			20,000,000	20,000,000
Preferred Stock, Par or Stated Value Per Share			$ 0.01		$ 0.01
Common stock, shares issued			46,659,144	46,658,990
Common Stock Voting Restrictions	10.00%
Common Stock Voting Restriction Less One Vote	10.00%
Common Stock Transfer Restrictions	5.00%
Common Stock Additional Transfer Restrictions		5.00%
Stockholders' Equity Attributable to Noncontrolling Interest			$ 53	$ 53
Ambac Assurance Corporation [Member]
Preferred Stock, Shares Outstanding			4,596	4,596
Preferred Stock, Liquidation Preference, Value			$ 115	$ 115
Stockholders' Equity Attributable to Noncontrolling Interest			$ 51