Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Noncontrolling Interest [Member]	Treasury Stock, Common	Nonredeemable Nonncontrolllng interest	Parent Company [Member]	Parent Company [Member] Retained Earnings [Member]	Parent Company [Member] AOCI Attributable to Parent [Member]	Parent Company [Member] Common Stock [Member]	Parent Company [Member] Additional Paid-in Capital [Member]	Parent Company [Member] Treasury Stock, Common
Beginning balance at Dec. 31, 2021	$ 1,098,073	$ 726,054	$ 57,611	$ 0	$ 465	$ 256,906	$ 59,968	$ (2,931)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	211,666	521,248	(310,454)							$ 210,794	$ 521,248	$ (310,454)
Stock-based compensation	17,408					17,408
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(3,568)	(5,446)						1,878		(3,568)	(5,446)				$ 1,878
Treasury Stock, Value, Acquired, Cost Method	(14,217)							14,217		14,217					14,217
Ending balance at Dec. 31, 2022	1,305,250	1,245,491	(252,843)	0	467	274,486	52,919	(15,270)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive gain (loss), net of tax, prior to gain on repurchase of Auction Mrket Securities	210,794
Noncontrolling Interest, Change in Redemption Value	2,504	2,504								2,504	2,504
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	2,173					172	2,001
Issuance of common stock	2				2					2			$ 2
Purchase of Ambac Assurance auction market preferred shares	(7,919)	1,131					(9,050)			1,131	1,131
Total comprehensive income (loss)	97,748	3,632	92,796							96,430	3,633	92,797
Stock-based compensation	17,275					17,275
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(4,665)	(7,872)						3,207		(4,665)	(7,872)				3,207
Treasury Stock, Value, Acquired, Cost Method	(4,510)							4,510		4,510					4,510
Ending balance at Dec. 31, 2023	1,414,614	1,246,048	(160,047)	0	467	291,761	52,958	(16,573)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest, Total, Excluding Gain on AMPS Repurchase	96,428
Noncontrolling Interest, Change in Redemption Value	4,836	4,797					39			4,797	4,797
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	2,450
Total comprehensive income (loss)	(584,478)	(556,449)	(28,390)							(584,839)	(556,449)	$ (28,390)
Stock-based compensation	8,995					8,995
Shares Issued, Value, Share-based Payment Arrangement, after Forfeiture	(701)	(634)						(67)		(701)	(634)				(67)
Treasury Stock, Value, Acquired, Cost Method	(11,699)							(11,699)		11,699					$ 11,699
Ending balance at Dec. 31, 2024	1,054,661	742,185	$ (188,436)	$ 0	489	331,007	197,755	$ (28,339)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest, Total, Excluding Gain on AMPS Repurchase	(584,839)
Noncontrolling Interest, Change in Redemption Value	49,966	$ 53,220				1,044	$ (4,298)			54,264	$ 53,220			$ 1,044
Issuance of common stock	29,229				$ 22	$ 29,207				$ 29,229			$ 22	$ 29,207
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value	$ 185,469								$ 149,095