Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues:
Net premiums earned (Note 8)	$ 286,471	$ 281,185	$ 813,181	$ 843,863
Services revenue (Note 4)	33,943	42,509	93,945	114,565
Net investment income	36,255	42,756	115,922	130,364
Net gains (losses) on investments and other financial instruments	17,652	13,009	42,901	47,462
Other income	913	879	2,807	2,677
Total revenues	375,234	380,338	1,068,756	1,138,931
Expenses:
Provision for losses	88,084	29,231	428,453	97,412
Policy acquisition costs	10,166	6,435	23,594	18,531
Cost of services	24,353	29,044	64,466	81,046
Other operating expenses	69,377	76,384	199,069	225,235
Interest expense	21,088	13,492	49,981	44,150
Loss on extinguishment of debt	0	5,940	0	22,738
Amortization and impairment of other acquired intangible assets	961	2,139	2,919	6,465
Total expenses	214,029	162,665	768,482	495,577
Consolidated pretax income (loss)	161,205	217,673	300,274	643,354
Income tax provision	26,102	44,235	54,661	132,229
Net income	$ 135,103	$ 173,438	$ 245,613	$ 511,125
Earnings Per Share, Basic [Abstract]
Basic net income (loss) per share	$ 0.70	$ 0.85	$ 1.25	$ 2.45
Earnings Per Share, Diluted [Abstract]
Diluted net income (loss) per share	$ 0.70	$ 0.83	$ 1.25	$ 2.39
Weighted-average number of common shares outstanding—basic	193,176	203,107	196,120	208,561
Weighted-average number of common and common equivalent shares outstanding—diluted	194,156	208,691	197,247	213,963