Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues
Net premiums earned (Note 8)	$ 271,872	$ 277,415
Services revenue (Note 4)	22,895	31,927
Net investment income	38,251	40,944
Net gains (losses) on investments and other financial instruments	(5,181)	(22,027)
Other income	976	822
Total revenues	328,813	329,081
Expenses
Provision for losses	46,143	35,951
Policy acquisition costs	8,996	7,413
Cost of Services	20,246	22,141
Other operating expenses	70,262	69,110
Interest expense	21,115	12,194
Amortization and impairment of other acquired intangible assets	862	979
Total expenses	167,624	147,788
Consolidated pretax income (loss)	161,189	181,293
Income tax provision	35,581	40,832
Net income	$ 125,608	$ 140,461
Earnings Per Share, Basic [Abstract]
Basic net income (loss) per share	$ 0.65	$ 0.70
Earnings Per Share, Diluted [Abstract]
Diluted net income (loss) per share	$ 0.64	$ 0.70
Weighted-average number of common shares outstanding—basic	193,439	200,161
Weighted-average number of common and common equivalent shares outstanding—diluted	195,203	201,819