CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 673,763	$ 670,097	$ 355,761
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and other amortization	48,784	58,215	64,430
Deferred tax expense	11,096	186,572	355,044
Net realized investment (gains) losses	(5,306)	1,353	(231)
Loss on debt extinguishment	0	0	65
Change in certain assets and liabilities:
Accrued investment income	(1,704)	(1,941)	(1,987)
Reinsurance recoverable on loss reserves	11,687	15,146	2,019
Reinsurance recoverable on paid losses	1,427	924	1,092
Premiums receivable	(497)	(1,045)	(1,653)
Deferred insurance policy acquisition costs	(643)	953	(1,082)
Profit commission receivable	4,945	(5,479)	(2,844)
Loss reserves	(118,685)	(311,616)	(453,178)
Unearned premiums	(29,683)	17,051	63,197
Return premium accrual	(11,500)	(22,900)	(25,400)
Current income taxes	1,057	(77,551)	51,296
Other, net	24,791	14,738	128
Net cash provided by operating activities	609,532	544,517	406,657
Cash flows from investing activities:
Purchases of investments	(1,394,126)	(1,459,473)	(1,293,695)
Proceeds from sales of investments	229,796	370,449	246,908
Proceeds from maturity of fixed income securities	748,165	785,175	759,212
Net (decrease) increase in payables for securities	(307)	307	0
Additions to property and equipment	(5,636)	(14,238)	(16,066)
Net cash used in investing activities	(422,108)	(317,780)	(303,641)
Cash flows from financing activities:
Proceeds from revolving credit facility	0	0	150,000
Repayment of revolving credit facility	0	0	(150,000)
Purchase or repayment of convertible senior notes	0	0	(145,620)
Payment of original issue discount - convertible senior notes	0	0	(4,504)
Repurchase of common stock	(125,766)	(163,419)	0
Dividends paid	(41,914)	0	0
Payment of debt issuance costs	0	0	(1,630)
Payment of withholding taxes related to share-based compensation net share settlement	(5,726)	(8,131)	(6,821)
Net cash used in financing activities	(173,406)	(171,550)	(158,575)
Net increase (decrease) in cash and cash equivalents and restricted cash and cash equivalents	14,018	55,187	(55,559)
Cash and cash equivalents and restricted cash and cash equivalents at beginning of year	155,038	99,851	155,410
Cash and cash equivalents and restricted cash and cash equivalents at end of year	$ 169,056	$ 155,038	$ 99,851