Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018	Jun. 30, 2019		Jun. 30, 2018
Revenues:
Net premiums earned—insurance	$ 299,166	[1]	$ 251,344	$ 562,678	[1]	$ 493,894
Services revenue	39,303		36,828	72,056		69,992
Net investment income	43,761		37,473	87,608		71,429
Net gains (losses) on investments and other financial instruments	12,540		(7,404)	34,453		(26,291)
Other income	194		1,016	1,798		1,823
Total revenues	394,964		319,257	758,593		610,847
Expenses:
Provision for losses	47,427		19,337	68,181		56,620
Policy acquisition costs	6,203		5,996	12,096		13,113
Cost of services	27,845		24,205	52,002		47,331
Other operating expenses	70,046		70,184	148,851		133,427
Restructuring and other exit costs (Note 1)	0		925	0		1,476
Interest expense	14,961		15,291	30,658		30,371
Loss on extinguishment of debt	16,798		0	16,798		0
Amortization and impairment of other acquired intangible assets	2,139		2,748	4,326		5,496
Total expenses	185,419		138,686	332,912		287,834
Consolidated pretax income (loss)	209,545		180,571	425,681		323,013
Income tax provision (benefit)	42,815		(28,378)	87,994		(422)
Net income	$ 166,730		$ 208,949	$ 337,687		$ 323,435
Earnings Per Share, Basic [Abstract]
Basic net income (loss) per share	$ 0.80		$ 0.98	$ 1.60		$ 1.50
Earnings Per Share, Diluted [Abstract]
Diluted net income (loss) per share	$ 0.78		$ 0.96	$ 1.56		$ 1.48
Weighted-average number of common shares outstanding—basic	208,097		213,976	211,264		215,049
Weighted-average number of common and common equivalent shares outstanding—diluted	213,603		217,830	216,500		218,741

[1] Includes a cumulative adjustment to unearned premiums recorded in the second quarter of 2019 related to an update to the amortization rates used to recognize revenue for Single Premium Policies. See Note 3 for further information.