NMI (NMIH) 10-Q 30 Jul 24 2024 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2024	Jul. 26, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Document Transition Report	false
Entity File Number	001-36174
Entity Registrant Name	NMI Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-4914248
Entity Address, Address Line One	2100 Powell Street
Entity Address, City or Town	Emeryville
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94608
City Area Code	855
Local Phone Number	530-6642
Title of 12(b) Security	Common Stock, par value $0.01
Trading Symbol	NMIH
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		79,672,652
Entity Central Index Key	0001547903
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands		Jun. 30, 2024	Dec. 31, 2023
Assets
Fixed maturities, available-for-sale, at fair value (amortized cost of $2,707,416 and $2,542,862 as of June 30, 2024 and December 31, 2023, respectively)		$ 2,520,990	$ 2,371,021
Cash and cash equivalents (including restricted cash of $1,152 and $1,338 as of June 30, 2024 and December 31, 2023, respectively)		62,629	96,689
Premiums receivable		76,455	76,456
Accrued investment income		21,439	19,785
Deferred policy acquisition costs, net		63,248	62,905
Software and equipment, net		28,848	30,252
Intangible assets and goodwill		3,634	3,634
Reinsurance recoverable		27,336	27,514
Prepaid federal income taxes		235,286	235,286
Other assets		62,038	16,965
Total assets		3,101,903	2,940,507
Liabilities
Debt		414,249	397,595
Unearned premiums		78,334	92,295
Accounts payable and accrued expenses		77,918	86,189
Reserve for insurance claims and claim expenses		125,443	123,974
Deferred tax liability, net		348,293	301,573
Other liabilities	[1]	12,056	12,877
Total liabilities		1,056,293	1,014,503
Commitments and contingencies
Shareholders' equity
Common stock - $0.01 par value; 87,900,888 shares issued and 79,763,893 shares outstanding as of June 30, 2024 and 87,334,138 shares issued and 80,881,280 shares outstanding as of December 31, 2023 (250,000,000 shares authorized)		879	873
Additional paid-in capital		993,143	990,816
Treasury Stock, at cost: 8,136,995 and 6,452,858 common shares as of June 30, 2024 and December 31, 2023, respectively		(201,323)	(148,921)
Accumulated other comprehensive loss, net of tax		(151,371)	(139,917)
Retained earnings		1,404,282	1,223,153
Total shareholders' equity		2,045,610	1,926,004
Total liabilities and shareholders' equity		$ 3,101,903	$ 2,940,507
[1]“Reinsurance funds withheld ” has been reclassified as “Other liabilities ” in the prior period.

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Debt securities, amortized cost	$ 2,707,416	$ 2,542,862
Restricted cash	$ 1,152	$ 1,338
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	87,900,888	87,334,138
Common stock, outstanding (in shares)	79,763,893	80,881,280
Common stock, authorized (in shares)	250,000,000	250,000,000
Treasury stock, common shares (in shares)	8,136,995	6,452,858

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenues
Net premiums earned	$ 141,168	$ 125,985	$ 277,825	$ 247,739
Net investment income	20,688	16,518	40,124	31,412
Net realized investment losses	0	0	0	(33)
Other revenues	266	182	426	346
Total revenues	162,122	142,685	318,375	279,464
Expenses
Insurance claims and claim expenses	276	2,873	3,970	9,574
Underwriting and operating expenses	28,330	27,448	58,145	53,234
Service expenses	194	267	331	347
Interest expense	14,678	8,048	22,718	16,087
Total expenses	43,478	38,636	85,164	79,242
Income before income taxes	118,644	104,049	233,211	200,222
Income tax expense	26,565	23,765	52,082	45,480
Net income	$ 92,079	$ 80,284	$ 181,129	$ 154,742
Earnings per share
Basic (in dollars per share)	$ 1.15	$ 0.97	$ 2.25	$ 1.86
Diluted (in dollars per share)	$ 1.13	$ 0.95	$ 2.22	$ 1.83
Weighted average common shares outstanding
Basic (in shares)	80,117	82,958	80,421	83,277
Diluted (in shares)	81,300	84,190	81,703	84,504
Comprehensive income:
Net income	$ 92,079	$ 80,284	$ 181,129	$ 154,742
Other comprehensive (loss) income, net of tax:
Unrealized (losses) gains in accumulated other comprehensive income, net of tax (benefit) expense of $(412) and $(4,120) for the three months ended June 30, 2024 and 2023, and $(3,141) and $4,513 for the six months ended June 30, 2024 and 2023, respectively	(1,549)	(15,499)	(11,454)	16,977
Reclassification adjustment for realized losses included in net income, net of tax benefit of $7 for the six months ended June 30, 2023	0	0	0	26
Other comprehensive (loss) income, net of tax	(1,549)	(15,499)	(11,454)	17,003
Comprehensive income	$ 90,530	$ 64,785	$ 169,675	$ 171,745

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Statement [Abstract]
Unrealized (losses) gains in accumulated other comprehensive income, net of tax (benefit) expense	$ (412)	$ (4,120)	$ (3,141)	$ 4,513
Reclassification adjustment for realized losses included in net income, net of tax benefit				$ 7

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock, At Cost	Accumulated Other Comprehensive Loss	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2022		83,550,000
Beginning balance at Dec. 31, 2022	$ 1,613,727	$ 865	$ 972,717	$ (56,575)	$ (204,323)	$ 901,043
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: shares issued under stock plans, net of shares withheld for employee taxes (in shares)		396,000
Common stock: shares issued under stock plans, net of shares withheld for employee taxes	(2,606)	$ 4	(2,610)
Repurchase of common stock (in shares)		(666,000)
Repurchase of common stock	(14,862)			(14,862)
Share-based compensation expense	3,492		3,492
Change in unrealized investment gains/losses, net of tax benefit/expense	32,502				32,502
Net income	74,458					74,458
Ending balance (in shares) at Mar. 31, 2023		83,280,000
Ending balance at Mar. 31, 2023	1,706,711	$ 869	973,599	(71,437)	(171,821)	975,501
Beginning balance (in shares) at Dec. 31, 2022		83,550,000
Beginning balance at Dec. 31, 2022	1,613,727	$ 865	972,717	(56,575)	(204,323)	901,043
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	154,742
Ending balance (in shares) at Jun. 30, 2023		82,290,000
Ending balance at Jun. 30, 2023	1,748,955	$ 870	977,295	(97,675)	(187,320)	1,055,785
Beginning balance (in shares) at Mar. 31, 2023		83,280,000
Beginning balance at Mar. 31, 2023	1,706,711	$ 869	973,599	(71,437)	(171,821)	975,501
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: shares issued under stock plans, net of shares withheld for employee taxes (in shares)		56,000
Common stock: shares issued under stock plans, net of shares withheld for employee taxes	21	$ 1	20
Repurchase of common stock (in shares)		(1,046,000)
Repurchase of common stock	(26,238)			(26,238)
Share-based compensation expense	3,676		3,676
Change in unrealized investment gains/losses, net of tax benefit/expense	(15,499)				(15,499)
Net income	80,284					80,284
Ending balance (in shares) at Jun. 30, 2023		82,290,000
Ending balance at Jun. 30, 2023	$ 1,748,955	$ 870	977,295	(97,675)	(187,320)	1,055,785
Beginning balance (in shares) at Dec. 31, 2023	80,881,280	80,881,000
Beginning balance at Dec. 31, 2023	$ 1,926,004	$ 873	990,816	(148,921)	(139,917)	1,223,153
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: shares issued under stock plans, net of shares withheld for employee taxes (in shares)		505,000
Common stock: shares issued under stock plans, net of shares withheld for employee taxes	(5,579)	$ 5	(5,584)
Repurchase of common stock (in shares)		(840,000)
Repurchase of common stock	(25,306)			(25,306)
Share-based compensation expense	4,117		4,117
Change in unrealized investment gains/losses, net of tax benefit/expense	(9,905)				(9,905)
Net income	89,050					89,050
Ending balance (in shares) at Mar. 31, 2024		80,546,000
Ending balance at Mar. 31, 2024	$ 1,978,381	$ 878	989,349	(174,227)	(149,822)	1,312,203
Beginning balance (in shares) at Dec. 31, 2023	80,881,280	80,881,000
Beginning balance at Dec. 31, 2023	$ 1,926,004	$ 873	990,816	(148,921)	(139,917)	1,223,153
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 181,129
Ending balance (in shares) at Jun. 30, 2024	79,763,893	79,764,000
Ending balance at Jun. 30, 2024	$ 2,045,610	$ 879	993,143	(201,323)	(151,371)	1,404,282
Beginning balance (in shares) at Mar. 31, 2024		80,546,000
Beginning balance at Mar. 31, 2024	1,978,381	$ 878	989,349	(174,227)	(149,822)	1,312,203
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock: shares issued under stock plans, net of shares withheld for employee taxes (in shares)		62,000
Common stock: shares issued under stock plans, net of shares withheld for employee taxes	(319)	$ 1	(320)
Repurchase of common stock (in shares)		(844,000)
Repurchase of common stock	(27,096)			(27,096)
Share-based compensation expense	4,114		4,114
Change in unrealized investment gains/losses, net of tax benefit/expense	(1,549)				(1,549)
Net income	$ 92,079					92,079
Ending balance (in shares) at Jun. 30, 2024	79,763,893	79,764,000
Ending balance at Jun. 30, 2024	$ 2,045,610	$ 879	$ 993,143	$ (201,323)	$ (151,371)	$ 1,404,282

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023
Statement of Stockholders' Equity [Abstract]
Change in unrealized investment gains/losses, tax expense (benefit)	$ (412)	$ (2,729)	$ (4,120)	$ 8,640

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Cash flows from operating activities
Net income	$ 181,129	$ 154,742
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment loss	0	33
Depreciation and amortization	5,990	5,642
Net amortization of premium on investment securities	785	2,077
Loss on extinguishment of debt	6,966	0
Amortization of debt discount and debt issuance costs	1,052	966
Deferred income taxes	49,861	43,765
Share-based compensation expense	8,231	7,168
Changes in operating assets and liabilities:
Premiums receivable	1	(2,687)
Accrued investment income	(1,654)	(3,249)
Deferred policy acquisition costs, net	(343)	(2,598)
Reinsurance recoverable	178	(2,436)
Other assets	(793)	166
Unearned premiums	(13,961)	(17,968)
Reserve for insurance claims and claim expenses	1,469	10,612
Reinsurance balances, net	(314)	(691)
Accounts payable and accrued expenses	(9,234)	(3,802)
Net cash provided by operating activities	229,363	191,740
Cash flows from investing activities
Purchase of short-term investments	(101,545)	(152,715)
Purchase of fixed-maturity investments, available-for-sale	(236,755)	(224,378)
Proceeds from maturities of short-term investments	37,700	189,670
Proceeds from maturities and redemptions of fixed-maturity investments, available-for-sale	92,260	72,503
Additions to software and equipment	(4,026)	(4,550)
Net cash used in investing activities	(212,366)	(119,470)
Cash flows from financing activities
Proceeds from issuance of common stock related to employee equity plans	4,280	2,711
Taxes paid related to net share settlement of equity awards	(10,178)	(5,296)
Proceeds from senior unsecured notes	419,705	0
Repayments of senior secured notes	(405,080)	0
Payments of debt issuance costs	(7,730)	0
Repurchases of common stock	(52,054)	(40,792)
Net cash used in financing activities	(51,057)	(43,377)
Net (decrease) increase in cash, cash equivalents and restricted cash	(34,060)	28,893
Cash, cash equivalents and restricted cash, beginning of period	96,689	44,426
Cash, cash equivalents and restricted cash, end of period	62,629	73,319
Supplemental disclosures of cash flow information
Interest paid	14,013	14,750
Income taxes paid	$ 20	$ 1

Organization, Basis of Presenta

Organization, Basis of Presentation and Summary of Accounting Principles	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Basis of Presentation and Summary of Accounting Principles	Organization, Basis of Presentation and Summary of Accounting Principles NMI Holdings, Inc. (NMIH) is a Delaware corporation, incorporated in May 2011 to provide private mortgage guaranty insurance (which we refer to as mortgage insurance or MI) through its wholly-owned insurance subsidiaries, National Mortgage Insurance Corporation (NMIC) and National Mortgage Reinsurance Inc One (Re One). Our common stock is listed on the Nasdaq exchange under the ticker symbol “NMIH.” NMIC, our primary insurance subsidiary, issued its first mortgage insurance policy in April 2013. NMIC is licensed to write mortgage insurance in all 50 states and the District of Columbia (D.C.). Re One historically provided reinsurance coverage to NMIC in accordance with certain statutory risk retention requirements. Such requirements have been repealed and the reinsurance coverage provided by Re One to NMIC has been commuted. Re One remains a wholly-owned, licensed insurance subsidiary; however, it does not currently have active insurance exposures. In August 2015, NMIH capitalized a wholly-owned subsidiary, NMI Services, Inc. (NMIS), through which we offer outsourced loan review services to mortgage loan originators. We operate as a single segment for the purposes of assessing performance and making operating decisions. Basis of Presentation The accompanying unaudited condensed consolidated financial statements, which include the results of NMIH and its wholly-owned subsidiaries, have been prepared in accordance with the instructions to Form 10-Q as prescribed by the SEC for interim reporting and include other information and disclosures required by accounting principles generally accepted in the U.S. (GAAP). Our accounts are maintained in U.S. dollars. These statements should be read in conjunction with our consolidated financial statements and notes thereto for the year ended December 31, 2023, included in our 2023 10-K. All intercompany transactions have been eliminated. Certain reclassifications to previously reported financial information have been made to conform to our current period presentation. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect reported amounts of assets and liabilities, as well as disclosure of contingent assets and liabilities as of the balance sheet date. Estimates also affect the reported amounts of income and expenses for the reporting period. Actual results could differ from those estimates. The results of operations for the interim period may not be indicative of the results that may be expected for the full year ending December 31, 2024. Significant Accounting Principles There have been no changes to our significant accounting principles as described in Item 8, “ Financial Statements and Supplementary Data - Notes to Consolidated Financial Statements - Note 2 - Summary of Accounting Principles” of our 2023 10-K. Recent Accounting Pronouncements – Not Yet Adopted In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280). The update expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. The standard will take effect for all public business entities, including those that have only a single reportable segment for fiscal years beginning after December 15, 2023, and interim periods beginning after December 31, 2024. We are currently evaluating the impact the adoption of this ASU will have, if any, on our consolidated financial statements.

Investments

Investments	6 Months Ended
	Jun. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Investments	Investments We hold all investments on an available-for-sale basis at fair value on our condensed consolidated balance sheets and evaluate each position quarterly for impairment. We recognize an impairment on a security through the statement of operations if (i) we intend to sell the impaired security; or (ii) it is more likely than not that we will be required to sell the impaired security prior to recovery of its amortized cost basis. If a sale is intended or likely to be required, we recognize an impairment loss equivalent to the difference of the amortized cost basis of the security and its fair value through the condensed consolidated statements of operations and comprehensive income as a “ Net Realized Investment Loss .” In the event of an impairment of a security that we intend to and have the ability to hold to maturity, we evaluate the drivers of the impairment to determine the portion that is credit related and the portion that is non-credit related. The portion of impairment loss that is attributed to credit related factors is recognized through the statement of operations as a provision for credit loss and the portion that is attributed to non-credit related factors is recognized in other comprehensive income, net of taxes. Fair Values and Gross Unrealized Gains and Losses on Investments Amortized Gross Unrealized Fair Gains Losses As of June 30, 2024 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 123,602 $ 1,149 $ (768) $ 123,983 Municipal debt securities 681,640 445 (59,469) 622,616 Corporate debt securities 1,767,760 2,083 (126,709) 1,643,134 Asset-backed securities 46,128 — (3,143) 42,985 Total bonds 2,619,130 3,677 (190,089) 2,432,718 Short-term investments 88,286 — (14) 88,272 Total investments $ 2,707,416 $ 3,677 $ (190,103) $ 2,520,990 Amortized Gross Unrealized Fair Gains Losses As of December 31, 2023 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 164,278 $ 3,374 $ (1,264) $ 166,388 Municipal debt securities 678,339 1,253 (58,462) 621,130 Corporate debt securities 1,624,187 7,868 (120,576) 1,511,479 Asset-backed securities 52,242 1 (4,032) 48,211 Total bonds 2,519,046 12,496 (184,334) 2,347,208 Short-term investments 23,816 2 (5) 23,813 Total investments $ 2,542,862 $ 12,498 $ (184,339) $ 2,371,021 We did not own any mortgage-backed securities in our asset-backed securities portfolio at June 30, 2024 or December 31, 2023. We periodically recognize unsettled trade receivables or payables in connection with our investing activity. Unsettled trade receivables represent funds due but not yet received for the sale or maturity of investments at period end. Unsettled trade payables represent funds due but not yet paid for investments purchased at period end. “Other Assets” on our condensed consolidated balance sheets included $43.0 million of unsettled trade receivables related to the maturity of certain investment securities at June 30, 2024. No unsettled trade receivables or payables were outstanding at December 31, 2023. The following table presents a breakdown of the fair value of our corporate debt securities by issuer industry group as of June 30, 2024 and December 31, 2023: June 30, 2024 December 31, 2023 Financial 35 % 35 % Consumer 27 26 Utilities 12 13 Industrial 10 9 Technology 8 8 Communications 8 9 Total 100 % 100 % As of both June 30, 2024 and December 31, 2023, approximately $5.3 million of our cash and investments were held in the form of U.S. Treasury securities on deposit with various state insurance departments to satisfy regulatory requirements. Scheduled Maturities The amortized cost and fair value of available-for-sale securities as of June 30, 2024 and December 31, 2023, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Because most asset-backed securities provide for periodic payments throughout their lives, they are listed below in a separate category. As of June 30, 2024 Amortized Fair (In Thousands) Due in one year or less $ 216,476 $ 214,664 Due after one through five years 1,418,059 1,331,158 Due after five through ten years 986,357 892,216 Due after ten years 40,396 39,967 Asset-backed securities 46,128 42,985 Total investments $ 2,707,416 $ 2,520,990 As of December 31, 2023 Amortized Fair (In Thousands) Due in one year or less $ 191,375 $ 189,729 Due after one through five years 1,237,192 1,162,259 Due after five through ten years 1,050,989 959,633 Due after ten years 11,064 11,189 Asset-backed securities 52,242 48,211 Total investments $ 2,542,862 $ 2,371,021 Aging of Unrealized Losses As of June 30, 2024, the investment portfolio had gross unrealized losses of $190.1 million, of which $184.8 million were associated with securities that had been in an unrealized loss position for a period of twelve months or longer. As of December 31, 2023, the investment portfolio had gross unrealized losses of $184.3 million, of which $183.1 million were associated with securities that had been in an unrealized loss position for a period of twelve months or longer. For those securities in an unrealized loss position, the length of time the securities were in such a position is as follows: Less Than Twelve Months Twelve Months or Greater Total # of Securities Fair Value Unrealized Losses # of Securities Fair Value Unrealized Losses # of Securities Fair Value Unrealized Losses As of June 30, 2024 ($ In Thousands) U.S. Treasury securities and obligations of U.S. government agencies 4 $ 12,598 $ (31) 11 $ 21,274 $ (737) 15 $ 33,872 $ (768) Municipal debt securities 22 114,419 (1,825) 223 484,737 (57,644) 245 599,156 (59,469) Corporate debt securities 52 305,550 (3,413) 245 1,104,989 (123,296) 297 1,410,539 (126,709) Asset-backed securities 1 567 — 23 42,418 (3,143) 24 42,985 (3,143) Short-term investments 5 87,891 (14) — — — 5 87,891 (14) Total 84 $ 521,025 $ (5,283) 502 $ 1,653,418 $ (184,820) 586 $ 2,174,443 $ (190,103) Less Than Twelve Months Twelve Months or Greater Total # of Securities Fair Value Unrealized Losses # of Securities Fair Value Unrealized Losses # of Securities Fair Value Unrealized Losses As of December 31, 2023 ($ In Thousands) U.S. Treasury securities and obligations of U.S. government agencies 8 $ 5,022 $ (62) 17 $ 72,003 $ (1,202) 25 $ 77,025 $ (1,264) Municipal debt securities 14 56,280 (502) 217 467,098 (57,960) 231 523,378 (58,462) Corporate debt securities 13 56,039 (705) 266 1,150,662 (119,871) 279 1,206,701 (120,576) Asset-backed securities — — — 23 47,426 (4,032) 23 47,426 (4,032) Short-term investments 1 9,925 (5) — — — 1 9,925 (5) Total 36 $ 127,266 $ (1,274) 523 $ 1,737,189 $ (183,065) 559 $ 1,864,455 $ (184,339) Allowance for Credit Losses As of June 30, 2024 and December 31, 2023, we did not recognize an allowance for credit loss for any security in the investment portfolio and we did not record any provision for credit loss for investment securities during the three or six months ended June 30, 2024 or 2023. We evaluated the securities in an unrealized loss position as of June 30, 2024, assessing their credit ratings as well as any adverse conditions specifically related to the security. Based upon our assessment of the amount and timing of cash flows to be collected over the remaining life of each instrument, we believe the unrealized losses as of June 30, 2024 are not indicative of the ultimate collectability of the current amortized cost of the securities. Rather, the unrealized losses on securities held as of June 30, 2024 were primarily driven by fluctuations in interest rates, and to a lesser extent, movements in credit spreads following the purchase of those securities. Net Investment Income The following table presents the components of net investment income: For the three months ended June 30, For the six months ended June 30, 2024 2023 2024 2023 (In Thousands) Investment income (1) $ 20,954 $ 16,591 $ 40,651 $ 31,765 Investment expenses (266) (73) (527) (353) Net investment income $ 20,688 $ 16,518 $ 40,124 $ 31,412 (1) Includes interest income recognized on cash and cash equivalents of $1.8 million and $2.9 million during the three and six months ended June 30, 2024, respectively, and $0.4 million and $0.7 million during the three and six months ended June 30, 2023, respectively. The following table presents the components of net realized investment losses: For the three months ended June 30, For the six months ended June 30, 2024 2023 2024 2023 (In Thousands) Gross realized investment gains $ — $ — $ — $ — Gross realized investment losses — — — (33) Net realized investment losses $ — $ — $ — $ (33)

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The following describes the valuation techniques used by us to determine the fair value of our financial instruments: We established a fair value hierarchy by prioritizing the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under this standard are described below: Level 1 - Fair value measurements based on quoted prices in active markets that we have the ability to access for identical assets or liabilities. Market price data generally is obtained from exchange or dealer markets. We do not adjust the quoted price for such instruments. Level 2 - Fair value measurements based on inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs other than quoted prices that are observable for the asset or liability, such as interest rates and yield curves that are observable at commonly quoted intervals. Level 3 - Fair value measurements based on valuation techniques that use significant inputs that are unobservable. Both observable and unobservable inputs may be used to determine the fair values of positions classified in Level 3. The circumstances for using these measurements include those in which there is little, if any, market activity for the asset or liability. Therefore, we must make certain assumptions, which require significant management judgment or estimation about the inputs a hypothetical market participant would use to value that asset or liability. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Assets Classified as Level 1 and Level 2 To determine the fair value of securities available-for-sale in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources have been utilized. One price is provided per security based on observable market data. To ensure securities are appropriately classified in the fair value hierarchy, we review the pricing techniques and methodologies of the independent pricing sources and believe that their policies adequately consider market activity, either based on specific transactions for the issue valued or based on modeling of securities with similar credit quality, duration, yield and structure that were recently traded. A variety of inputs are utilized by the independent pricing sources including benchmark yields, reported trades, non-binding broker/dealer quotes, issuer spreads, two sided markets, benchmark securities, bids, offers and reference data including data published in market research publications. Inputs may be weighted differently for any security, and not all inputs are used for each security evaluation. Market indicators, industry and economic events are also considered. This information is evaluated using a multidimensional pricing model. Quality controls are performed by the independent pricing sources throughout this process, which include reviewing tolerance reports, trading information and data changes, and directional moves compared to market moves. This model combines all inputs to arrive at a value assigned to each security. We have not made any adjustments to the prices obtained from the independent pricing sources. The following tables present the level within the fair value hierarchy at which our financial instruments were measured: Fair Value Measurements Using Quoted Prices in Significant Other Significant Fair Value As of June 30, 2024 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 123,983 $ — $ — $ 123,983 Municipal debt securities — 622,616 — 622,616 Corporate debt securities — 1,643,134 — 1,643,134 Asset-backed securities — 42,985 — 42,985 Cash, cash equivalents and short-term investments 150,901 — — 150,901 Total assets $ 274,884 $ 2,308,735 $ — $ 2,583,619 Fair Value Measurements Using Quoted Prices in Significant Other Significant Fair Value As of December 31, 2023 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 166,388 $ — $ — $ 166,388 Municipal debt securities — 621,130 — 621,130 Corporate debt securities — 1,511,479 — 1,511,479 Asset-backed securities — 48,211 — 48,211 Cash, cash equivalents and short-term investments 120,502 — — 120,502 Total assets $ 286,890 $ 2,180,820 $ — $ 2,467,710 There were no transfers between Level 2 and Level 3 of the fair value hierarchy during the six months ended June 30, 2024 or the year ended December 31, 2023. Financial Instruments Not Measured at Fair Value On May 21, 2024, we issued $425 million aggregate principal amount of senior unsecured notes that mature on August 15, 2029 (the 2024 Notes). Proceeds from the 2024 Notes offering were primarily used to repay our then outstanding $400 million senior secured notes (the 2020 Notes). At June 30, 2024, the 2024 Notes were carried at a cost of $414.2 million, net of unamortized debt issuance costs and an original issue discount totaling $10.8 million, and had a fair value of $421.6 million as assessed under our Level 2 hierarchy. At December 31, 2023, the 2020 Notes were carried at a cost of $397.6 million, net of unamortized debt issuance costs of $2.4 million, and had a fair value of $401.9 million.

Debt

Debt	6 Months Ended
	Jun. 30, 2024
Debt Disclosure [Abstract]
Debt	Debt Senior Unsecured Notes At June 30, 2024, we had $425 million aggregate principal amount of senior unsecured notes outstanding. The 2024 Notes were issued pursuant to an indenture dated May 21, 2024 and bear interest at a rate of 6.00%, payable semi-annually on February 15 and August 15. Proceeds from the 2024 Notes offering were primarily used to repay the $400 million aggregate principal amount outstanding and associated amounts due on the redemption of the 2020 Notes. Remaining proceeds are available for general corporate purposes. The 2024 Notes mature on August 15, 2029. We may elect to redeem the 2024 Notes in whole or in part at any time prior to July 15, 2029 at a price equal to the greater of (1) the aggregate principal balance outstanding plus the present value of all future interest payments due through July 15, 2029, and (2) the aggregate principal balance due plus any accrued and unpaid interest. We may elect to redeem the 2024 Notes in whole or in part at any time on or after July 15, 2029 at a price equal to 100% of the aggregate principal amount of the 2024 Notes to be redeemed plus accrued and unpaid interest thereon . In connection with the 2024 Notes offering, we recorded capitalized debt issuance costs and an original issue discount of $10.9 million. Such amounts will be amortized over the contractual life of the 2024 Notes using the effective interest method. The effective interest rate on the 2024 Notes is 6.583%. At June 30, 2024, $10.8 million of unamortized debt issuance costs and original issue discounts remained. At December 31, 2023, $2.4 million of unamortized debt issuance costs remained related to the 2020 Notes. During the six months ended June 30, 2024, we recorded a $6.8 million loss related to the redemption of the 2020 Notes in “Interest Expense” on our condensed consolidated statements of comprehensive income. At June 30, 2024 and December 31, 2023, $2.8 million and $2.5 million, respectively, of accrued and unpaid interest was included in “Accounts Payable and Accrued Expenses” on our condensed consolidated balance sheets. Revolving Credit Facility On April 29, 2024, we entered into a new $250 million five-year unsecured revolving credit facility (the 2024 Revolving Credit Facility) to replace our then outstanding $250 million four-year secured revolving credit facility (the 2021 Revolving Credit Facility). The 2024 Revolving Credit Facility matures on May 21, 2029. Borrowings under the 2024 Revolving Credit Facility may be used for general corporate purposes, including to support growth, new business production and operations, and accrue interest at a variable rate equal to, at our discretion, (i) a Base Rate (as defined in the 2024 Revolving Credit Facility) subject to a floor of 1.00% per annum plus a margin of 0.375% to 1.875% per annum, or (ii) the Adjusted Term Secured Overnight Financing Rate (SOFR) (as defined in the 2024 Revolving Credit Facility) plus a margin of 1.375% to 2.875% per annum, with the margin in each of (i) or (ii) based on our applicable corporate credit rating at the time. As of June 30, 2024 and December 31, 2023, no amounts were drawn under the 2024 or 2021 Revolving Credit Facilities, respectively. Under the 2024 Revolving Credit Facility, we are required to pay a quarterly commitment fee on the average daily undrawn amount of 0.175% to 0.525%, based on the applicable corporate credit rating at the time. As of June 30, 2024, the applicable commitment fee was 0.225%. For the three and six months ended June 30, 2024, we recorded $0.2 million and $0.3 million, respectively, of commitment fees in interest expense. We incurred debt issuance costs of $2.1 million in connection with the 2024 Revolving Credit Facility and had $0.6 million of unamortized debt issuance costs associated with the 2021 Revolving Credit Facility remaining at the time of its replacement. Combined unamortized debt issuance costs are amortized through interest expense on a straight-line basis over the contractual life of the 2024 Revolving Credit Facility. At June 30, 2024 and December 31, 2023, unamortized deferred debt issuance costs of $2.6 million and $0.8 million, respectively, were recorded in “Other Assets” on our condensed consolidated balance sheets. Under the 2024 Revolving Credit Facility we are subject to certain covenants, including a maximum debt-to-total capitalization ratio of 35%, a minimum consolidated net worth requirement (as defined therein), and a requirement to maintain compliance with the financial standards prescribed by the PMIERs (subject to any GSE approved waivers). We were in compliance with all covenants at June 30, 2024.

Reinsurance

Reinsurance	6 Months Ended
	Jun. 30, 2024
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance We enter into third-party reinsurance transactions to actively manage our risk, ensure compliance with PMIERs, state regulatory and other applicable capital requirements, (respectively, as defined therein), and support the growth of our business. The Wisconsin Office of the Commissioner of Insurance (Wisconsin OCI) has approved and the GSEs have indicated their non-objection to all such transactions (subject to certain conditions and ongoing review). The effect of our reinsurance agreements on premiums written and earned is as follows: For the three months ended June 30, For the six months ended June 30, 2024 2023 2024 2023 (In Thousands) Net premiums written Direct $ 166,183 $ 151,992 $ 329,390 $ 300,924 Ceded (1) (32,369) (34,848) (65,331) (70,804) Net premiums written $ 133,814 $ 117,144 $ 264,059 $ 230,120 Net premiums earned Direct $ 173,633 $ 160,988 $ 343,351 $ 318,892 Ceded (1) (32,465) (35,003) (65,526) (71,153) Net premiums earned $ 141,168 $ 125,985 $ 277,825 $ 247,739 (1) Net of profit commission. Excess-of-loss Reinsurance Insurance-Linked Notes NMIC is a party to reinsurance agreements with Oaktown Re III Ltd., Oaktown Re V Ltd., Oaktown Re VI Ltd., and Oaktown Re VII Ltd. (special purpose reinsurance entities collectively referred to as the Oaktown Re Vehicles) effective July 30, 2019, October 29, 2020, April 27, 2021, and October 26, 2021, respectively. Each agreement provides NMIC with aggregate excess-of-loss reinsurance coverage on a defined portfolio of mortgage insurance policies. Under each agreement, NMIC retains a first layer of aggregate loss exposure on covered policies and the respective Oaktown Re Vehicle then provides second layer loss protection up to a defined reinsurance coverage amount. NMIC then retains losses in excess of the respective reinsurance coverage amounts. NMIC makes risk premium payments to the Oaktown Re Vehicles for the applicable outstanding reinsurance coverage amount and pays an additional amount for anticipated operating expenses (capped at $250 thousand per year). NMIC ceded aggregate premiums to the Oaktown Re Vehicles of $5.9 million and $11.8 million during the three and six months ended June 30, 2024, respectively, and $8.8 million and $17.9 million during the three and six months ended June 30, 2023, respectively. NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure under each excess-of-loss agreement. NMIC did not cede any incurred losses on covered policies to the Oaktown Re Vehicles during the three and six months ended June 30, 2024 and 2023, as the aggregate first layer risk retention for each applicable agreement was not exhausted during such periods. Under the terms of each excess-of-loss reinsurance agreement, the Oaktown Re Vehicles are required to fully collateralize their outstanding reinsurance coverage amount to NMIC with funds deposited into segregated reinsurance trusts. Such trust funds are required to be invested in short-term U.S. Treasury money market funds at all times. Each Oaktown Re Vehicle financed its respective collateral requirement through the issuance of mortgage insurance-linked notes to unaffiliated investors. Such insurance-linked notes mature ten-years (in the case of the notes issued by Oaktown Re III Ltd. and Oaktown Re V Ltd.) and 12.5 years (in the case of the notes issued by Oaktown Re VI Ltd. and Oaktown Re VII Ltd.) from the inception date of their associated reinsurance agreement. We refer to NMIC’s reinsurance agreements with and the insurance-linked note issuances by Oaktown Re Vehicles individually as the 2019 ILN Transaction, 2020-2 ILN Transaction, 2021-1 ILN Transaction, and 2021-2 ILN Transaction, and collectively as the ILN Transactions. The respective reinsurance coverage amounts provided by the Oaktown Re Vehicles decrease (over a ten-year period in the case of Oaktown Re III Ltd. and Oaktown Re V Ltd. and 12.5-year period in the case of Oaktown Re VI Ltd. and Oaktown Re VII Ltd.) as the underlying insured mortgages are amortized or repaid, and/or the mortgage insurance coverage is canceled. As the reinsurance coverage decreases, a prescribed amount of collateral held in trust by the Oaktown Re Vehicles is distributed to ILN Transaction noteholders as amortization of the outstanding insurance-linked note principal balances. The outstanding reinsurance coverage amounts stop amortizing, and the distribution of collateral assets to ILN Transaction noteholders and amortization of insurance-linked note principal is suspended if certain credit enhancement or delinquency thresholds, as defined in each agreement, are triggered (each, a Lock-Out Event). NMIC holds optional termination rights under each ILN Transaction, including, among others, an optional call feature which provides NMIC the discretion to terminate the transaction on or after a prescribed date, and a clean-up call if the outstanding reinsurance coverage amount amortizes to 10% or less of the reinsurance coverage amount at inception or if NMIC reasonably determines that changes to GSE or rating agency asset requirements would cause a material and adverse effect on the capital treatment afforded to NMIC under a given agreement. In addition, there are certain events that trigger mandatory termination of an agreement, including NMIC's failure to pay premiums or consent to reductions in a trust account to make principal payments to noteholders, among others. The following table presents the inception date, covered production period, initial and current reinsurance coverage amount, and initial and current first layer retained aggregate loss under each outstanding ILN Transaction. Current amounts are presented as of June 30, 2024. ( $ values in thousands) Inception Date Covered Production Initial Reinsurance Coverage Current Reinsurance Coverage Initial First Layer Retained Loss Current First Layer Retained Loss (1) 2019 ILN Transaction July 30, 2019 6/1/2018 – 6/30/2019 $ 326,905 $ 143,430 $ 123,424 $ 121,588 2020-2 ILN Transaction October 29, 2020 4/1/2020 – 9/30/2020 (2) 242,351 37,165 121,777 121,015 2021-1 ILN Transaction April 27, 2021 10/1/2020 – 3/31/2021 (3) 367,238 180,516 163,708 163,321 2021-2 ILN Transaction October 26, 2021 4/1/2021 – 9/30/2021 (4) 363,596 273,706 146,229 145,549 (1) NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure and cedes reserves for incurred claims and claim expenses to each applicable ILN Transaction and recognizes a reinsurance recoverable if such incurred claims and claim expenses exceed its current first layer retained loss. (2) Approximately 1% of the production covered by the 2020-2 ILN Transaction has coverage reporting dates between July 1, 2019 and March 31, 2020. (3) Approximately 1% of the production covered by the 2021-1 ILN Transaction has coverage reporting dates between July 1, 2019 and September 30, 2020. (4) Approximately 2% of the production covered by the 2021-2 ILN Transaction has coverage reporting dates between July 1, 2019 and March 31, 2021. Under the terms of our ILN Transactions, we are required to maintain a certain level of restricted funds in premium deposit accounts with Bank of New York Mellon until the respective notes have been redeemed in full. “Cash and Cash Equivalents” on our condensed consolidated balance sheets includes restricted amounts of $1.2 million and $1.3 million as of June 30, 2024 and December 31, 2023, respectively. The restricted balances required under these transactions will decline over time as the outstanding principal balance of the respective insurance-linked notes are amortized. Traditional Reinsurance NMIC is party to six excess-of-loss reinsurance agreements with broad panels of third-party reinsurers – the 2022-1 XOL Transaction, effective April 1, 2022, the 2022-2 XOL Transaction, effective July 1, 2022, the 2022-3 XOL Transaction, effective October 1, 2022, the 2023-1 XOL Transaction, effective January 1, 2023, the 2023-2 XOL Transaction, effective July 1, 2023, and the 2024 XOL Transaction, effective January 1, 2024 – which we refer to collectively as the XOL Transactions. Each XOL Transaction provides NMIC with aggregate excess-of-loss reinsurance coverage on a defined portfolio of mortgage insurance policies. Under each agreement, NMIC retains a first layer of aggregate loss exposure on covered policies and the reinsurers then provide second layer loss protection up to a defined reinsurance coverage amount. The reinsurance coverage amount of each XOL Transaction is set to approximate the PMIERs minimum required assets of its reference pool and decreases from its peak over a ten-year period in the event the PMIERs minimum required assets of the pool declines. NMIC retains losses in excess of the outstanding reinsurance coverage amount. Under the terms of the XOL Transactions, NMIC makes risk premium payments to its third-party reinsurance providers for the outstanding reinsurance coverage amount and ceded aggregate premiums of $9.4 million and $18.6 million during the three and six months ended June 30, 2024, respectively, and $7.7 million and $14.9 million during the three and six months ended June 30, 2023, respectively. NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure under each agreement. NMIC did not cede any incurred losses on covered policies under the XOL Transactions during the three and six months ended June 30, 2024 and 2023, as the aggregate first layer risk retention for each agreement was not exhausted during such periods. NMIC holds optional termination rights which provide it the discretion to terminate each XOL Transaction on or after a specified date. NMIC may also elect to terminate the XOL Transactions at any point if the outstanding reinsurance coverage amount amortizes to 10% or less of the reinsurance coverage amount provided at inception, or if it determines that it will no longer be able to take full PMIERs asset credit for the coverage. Additionally, under the terms of the treaties, NMIC may selectively terminate its engagement with individual reinsurers under certain circumstances. Such selective termination rights arise when, among other reasons, a reinsurer experiences a deterioration in its capital position below a prescribed threshold, and/or a reinsurer breaches (and fails to cure) its collateral posting obligation. Each of the third-party reinsurance providers that is party to the XOL Transactions has an insurer financial strength rating of A- or better by S&P Global Ratings (S&P), A.M. Best Company Inc. (A.M. Best) or both. The following table presents the inception date, covered production period, initial and current reinsurance coverage amount, and initial and current first layer retained aggregate loss under each outstanding XOL Transaction. Current amounts are presented as of June 30, 2024. ($ values in thousands) Inception Date Covered Production Initial Reinsurance Coverage Current Reinsurance Coverage Initial First Layer Retained Loss Current First Layer Retained Loss (1) 2022-1 XOL Transaction April 1, 2022 10/1/2021 – 3/31/2022 (2) $ 289,741 $ 213,416 $ 133,366 $ 132,863 2022-2 XOL Transaction July 1, 2022 4/1/2022 – 6/30/2022 (3) 154,306 135,669 78,906 78,518 2022-3 XOL Transaction October 1, 2022 7/1/2022 – 9/30/2022 96,779 96,197 106,265 105,961 2023-1 XOL Transaction January 1, 2023 10/1/2022 – 6/30/2023 89,864 88,351 146,513 146,218 2023-2 XOL Transaction July 1, 2023 7/1/2023 – 12/31/2023 100,777 100,777 136,875 136,875 2024 XOL Transaction (4) January 1, 2024 1/1/2024 – 12/31/2024 86,477 86,477 151,609 151,609 (1) NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure and cedes reserves for incurred claims and claim expenses to each applicable XOL Transaction and recognizes a reinsurance recoverable if such incurred claims and claim expenses exceed its current first layer retained loss. (2) Approximately 1% of the production covered by the 2022-1 XOL Transaction has coverage reporting dates between October 21, 2019 and September 30, 2021. (3) Approximately 1% of the production covered by the 2022-2 XOL Transaction has coverage reporting dates between January 4, 2021 and March 31, 2022. (4) The initial reinsurance coverage, current reinsurance coverage, initial first layer retained loss and current first layer retained loss for the 2024 XOL Transaction will increase as incremental covered production is ceded under the transaction through December 31, 2024. Quota Share Reinsurance NMIC is party to eight quota share reinsurance treaties – the 2016 QSR Transaction, effective September 1, 2016 and as modified April 1, 2019, the 2018 QSR Transaction, effective January 1, 2018, the 2020 QSR Transaction, effective April 1, 2020 and as amended January 1, 2024, the 2021 QSR Transaction, effective January 1, 2021, the 2022 QSR Transaction, effective October 1, 2021, the 2022 Seasoned QSR Transaction, effective July 1, 2022, the 2023 QSR Transaction, effective January 1, 2023 and the 2024 QSR Transaction, effective January 1, 2024 – which we refer to collectively as the QSR Transactions. Under each of the QSR Transactions, NMIC cedes a proportional share of its risk on eligible policies to panels of third-party reinsurance providers. Each of the third-party reinsurance providers that is party to the QSR Transactions has an insurer financial strength rating of A- or better by S&P, A.M. Best or both. Under the terms of the 2016 QSR Transaction, NMIC cedes premiums written related to 20.5% of the risk on eligible primary policies written for all periods through December 31, 2017 and 100% of the risk under our pool agreement with Fannie Mae. The 2016 QSR Transaction is scheduled to terminate on December 31, 2027, except with respect to the ceded pool risk, which expired on August 31, 2023. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2020, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk. Under the terms of the 2018 QSR Transaction, NMIC cedes premiums earned related to 25% of the risk on eligible policies written in 2018 and 20% of the risk on eligible policies written in 2019. The 2018 QSR Transaction is scheduled to terminate on December 31, 2029. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2022, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk. Under the terms of the 2020 QSR Transaction, NMIC cedes premiums earned related to 21% of the risk on eligible policies written between April 1, 2020 and December 31, 2020. The 2020 QSR Transaction is scheduled to terminate on December 31, 2030. NMIC had the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2025, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk. Under the terms of the 2021 QSR Transaction, NMIC cedes premiums earned related to 22.5% of the risk on eligible policies written from January 1, 2021 to October 30, 2021. The 2021 QSR Transaction is scheduled to terminate on December 31, 2031. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2024, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk. Under the terms of the 2022 QSR Transaction, NMIC cedes premiums earned related to 20% of the risk on eligible policies written primarily between October 30, 2021 and December 31, 2022. The 2022 QSR Transaction is scheduled to terminate on December 31, 2032. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2024 or semi-annually thereafter, which could result in NMIC recapturing the related risk. Under the terms of the 2022 Seasoned QSR Transaction, NMIC cedes premiums earned related to 95% of the net risk on eligible policies primarily for a seasoned pool of mortgage insurance policies that had previously been covered under the retired Oaktown Re Ltd. and Oaktown Re IV Ltd. reinsurance transactions, after the consideration of coverage provided by other QSR Transactions. The 2022 Seasoned QSR Transaction is scheduled to terminate on June 30, 2032. NMIC has the option, based on certain conditions, to terminate the agreement as of June 30, 2025 or quarterly thereafter through December 31, 2027 with the payment of a termination fee, and as of March 31, 2028 or quarterly thereafter without the payment of a termination fee. Such termination could result in NMIC recapturing the related risk. Under the terms of the 2023 QSR Transaction, NMIC cedes premiums earned related to 20% of the risk on eligible policies written in 2023. The 2023 QSR Transaction is scheduled to terminate on December 31, 2033. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2025 or semi-annually thereafter, which could result in NMIC recapturing the related risk. Under the terms of the 2024 QSR Transaction, NMIC cedes premiums earned related to 20% of the risk on eligible policies written in 2024. The 2024 QSR Transaction is scheduled to terminate on December 31, 2034. NMIC has the option, based on certain conditions and subject to a termination fee, to terminate the agreement as of December 31, 2027, or at the end of any calendar quarter thereafter, which could result in NMIC recapturing the related risk. NMIC may terminate any or all of the QSR Transactions without penalty if, due to a change in PMIERs requirements, it is no longer able to take full PMIERs asset credit for the risk-in-force (RIF) ceded under the respective agreements. Additionally, under the terms of the QSR Transactions, NMIC may elect to selectively terminate its engagement with individual reinsurers on a run-off basis ( i.e. , reinsurers continue providing coverage on all risk ceded prior to the termination date, with no new cessions going forward) or cut-off basis ( i.e. , the reinsurance arrangement is completely terminated with NMIC recapturing all previously ceded risk) under certain circumstances. Such selective termination rights arise when, among other reasons, a reinsurer experiences a deterioration in its capital position below a prescribed threshold and/or a reinsurer breaches (and fails to cure) its collateral posting obligations under the relevant agreement. The following table shows amounts related to the QSR Transactions: As of and for the three months ended As of and for the six months ended June 30, 2024 June 30, 2023 June 30, 2024 June 30, 2023 (In Thousands) Ceded risk-in-force $ 12,815,434 $ 12,761,294 $ 12,815,434 $ 12,761,294 Ceded premiums earned (41,555) (42,002) (82,824) (84,098) Ceded claims and claim (benefits) expenses (138) 803 521 2,768 Ceding commission earned 10,222 9,877 20,514 19,842 Profit commission 24,351 23,486 47,758 45,765 Ceded premiums written under the 2016 QSR Transaction are recorded as prepaid reinsurance premiums in “Other Assets” on our consolidated balance sheets and amortized to ceded premiums earned in a manner consistent with the recognition of revenue on direct premiums. Under all other QSR Transactions, premiums are ceded on an earned basis as defined in the agreement. NMIC receives a 20% ceding commission for premiums ceded under the QSR Transactions, except with respect to the 2022 Seasoned QSR Transaction under which it receives a 35% ceding commission and the 2020 QSR Transaction under which it receives a 36% ceding commission. NMIC also receives a profit commission under each of the QSR Transactions, provided that the loss ratios on loans covered under the 2016, 2018, 2020, 2021, 2022, 2022 Seasoned, 2023 and 2024 QSR Transactions, generally remain below 60%, 61%, 50%, 57.5%, 62%, 55%, 62% and 56%, respectively, as measured annually. Ceded claims and claim expenses under each of the QSR Transactions reduce the respective profit commission received by NMIC on a dollar-for-dollar basis. In accordance with the terms of the 2016 QSR Transaction, rather than making a cash payment or transferring investments for ceded premiums written, NMIC established a funds withheld liability, which also includes amounts due to NMIC for ceding and profit commissions. Any loss recoveries and any potential profit commission to NMIC are realized from this account until exhausted. NMIC’s reinsurance recoverable balance is further supported by trust accounts established and maintained by each reinsurer in accordance with the PMIERs funding requirements for risk ceded to non-affiliates. The reinsurance recoverable on loss reserves related to the 2016 QSR Transaction was $1.4 million and $1.7 million as of June 30, 2024 and December 31, 2023, respectively. In accordance with the terms of the 2018, 2020, 2021, 2022, 2022 Seasoned, 2023 and 2024 QSR Transactions, cash payments for ceded premiums earned are settled on a quarterly basis, offset by amounts due to NMIC for ceding and profit commissions. Any loss recoveries and any potential profit commission to NMIC are also recognized quarterly. NMIC's reinsurance recoverable balance is supported by trust accounts established and maintained by each reinsurer in accordance with the PMIERs funding requirements for risk ceded to non-affiliates. The aggregate reinsurance recoverable on loss reserves related to the 2018, 2020, 2021, 2022, 2022 Seasoned, 2023, and 2024 QSR Transactions was $25.9 million and $25.8 million as of June 30, 2024 and December 31, 2023, respectively. We remain directly liable for all claim payments if we are unable to collect the recoverables due from our reinsurers and, as such, we actively monitor and manage our counterparty credit exposure to our reinsurance providers. We establish an allowance for expected credit loss against our reinsurance recoverable if we do not expect to recover amounts due from one or more of our reinsurance counterparties, and report our reinsurance recoverable net of such allowance, if any. We actively monitor the counterparty credit profiles of our reinsurers and each is required to partially collateralize its obligations under the terms of the QSR Transactions. The allowance for credit loss established against our reinsurance recoverable was deemed immaterial as of June 30, 2024 and December 31, 2023.

Reserves for Insurance Claims a

Reserves for Insurance Claims and Claim Expenses	6 Months Ended
	Jun. 30, 2024
Insurance [Abstract]
Reserves for Insurance Claims and Claim Expenses	Reserves for Insurance Claims and Claim Expenses We hold gross reserves in an amount equal to the estimated liability for insurance claims and claim expenses related to defaults on insured mortgage loans. A loan is considered to be in “default” as of the payment date at which a borrower has missed the preceding two or more consecutive monthly payments. We establish reserves for loans that have been reported to us in default by servicers, referred to as case reserves, and additional loans that we estimate (based on actuarial review and other factors) to be in default that have not yet been reported to us by servicers, referred to as incurred but not reported (IBNR) reserves. We also establish reserves for claim expenses, which represent the estimated cost of the claim administration process, including legal and other fees, as well as other general expenses of administering the claim settlement process. As of June 30, 2024, we held gross reserves for insurance claims and claim expenses of $125.4 million. During the six months ended June 30, 2024, we paid 101 claims totaling $3.0 million, including 97 claims covered under the QSR Transactions representing $0.7 million of ceded claims and claim expenses. We had 4,904 loans in default in our primary insured portfolio as of June 30, 2024, which represented a 0.76% default rate against 645,276 total policies in-force and 5,099 loans in default in our primary portfolio as of December 31, 2023, which represented a 0.81% default rate against 629,690 total policies in-force. The size of the reserve we establish for each defaulted loan (and by extension our aggregate reserve for claims and claim expenses) reflects our best estimate of the future claim payment to be made for each individual loan in default. Our future claims exposure is a function of the number of defaulted loans that progress to claim payment (which we refer to as frequency) and the amount to be paid to settle such claims (which we refer to as severity). Our estimates of claims frequency and severity are not formulaic, rather they are broadly synthesized based on historical observed experience for similarly situated loans and assumptions about future macroeconomic factors. The following table provides a reconciliation of the beginning and ending gross reserve balances for primary insurance claims and claim expenses: For the six months ended June 30, 2024 2023 (In Thousands) Beginning balance $ 123,974 $ 99,836 Less reinsurance recoverables (1) (27,514) (21,587) Beginning balance, net of reinsurance recoverables 96,460 78,249 Add claims incurred: Claims and claim expenses incurred: Current year (2) 50,372 44,870 Prior years (3) (46,402) (35,296) Total claims and claim expenses incurred 3,970 9,574 Less claims paid: Claims and claim expenses paid: Current year (2) — 54 Prior years (3) 2,323 1,344 Total claims and claim expenses paid 2,323 1,398 Reserve at end of period, net of reinsurance recoverables 98,107 86,425 Add reinsurance recoverables (1) 27,336 24,023 Ending balance $ 125,443 $ 110,448 (1) Related to ceded losses recoverable under the QSR Transactions. See Note 5, “ Reinsurance” for additional information. (2) Related to insured loans with their most recent defaults occurring in the current year. For example, if a loan defaulted in a prior year and subsequently cured and later re-defaulted in the current year, the default would be included in the current year. Amounts are presented net of reinsurance and included $43.1 million attributed to net case reserves and $6.4 million attributed to net IBNR reserves for the six months ended June 30, 2024 and $39.1 million attributed to net case reserves and $5.0 million attributed to net IBNR reserves for the six months ended June 30, 2023. (3) Related to insured loans with defaults occurring in prior years, which have been continuously in default before the start of the current year. Amounts are presented net of reinsurance and included $39.2 million attributed to net case reserves and $6.3 million attributed to net IBNR reserves for the six months ended June 30, 2024 and $30.3 million attributed to net case reserves and $4.5 million attributed to net IBNR reserves for the six months ended June 30, 2023. The “claims incurred” section of the table above shows claims and claim expenses incurred on defaults occurring in current and prior years, including IBNR reserves, and is presented net of reinsurance. The amount of claims incurred relating to current year defaults increased during the six months ended June 30, 2024, compared to the same period in the prior year, primarily due to an increase in the total number of new delinquencies emerging during the period tied to the growth and natural seasoning of our portfolio, partially offset by a decrease in the average case reserve established against newly defaulted loans. Our provision for claims and claim expenses during both the six months ended June 30, 2024 and 2023 benefited from favorable development on prior year defaults. We recognized $46.4 million and $35.3 million of favorable prior year development during the six months ended June 30, 2024 and 2023, respectively, primarily due to cure activity and ongoing analysis of recent loss development trends. We may increase or decrease our claim estimates and reserves as we learn additional information about individual defaulted loans, and continue to observe and analyze loss development trends in our portfolio. Gross reserves of $61.4 million related to prior year defaults remained as of June 30, 2024.

Earnings per Share (EPS)

Earnings per Share (EPS)	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Earnings per Share (EPS)	Earnings per Share (EPS) Basic EPS is based on the weighted average number of shares of common stock outstanding. Diluted EPS is based on the weighted average number of shares of common stock outstanding and common stock equivalents that would be issuable upon the vesting of service-based and performance and service-based restricted stock units (RSUs), and the exercise of vested and unvested stock options. The following table reconciles the net income and the weighted average shares of common stock outstanding used in the computations of basic and diluted EPS of common stock: For the three months ended June 30, For the six months ended June 30, 2024 2023 2024 2023 (In Thousands, except for per share data) Net income – basic and diluted $ 92,079 $ 80,284 $ 181,129 $ 154,742 Basic weighted average shares outstanding 80,117 82,958 80,421 83,277 Dilutive effect of issuable shares 1,183 1,232 1,282 1,227 Diluted weighted average shares outstanding 81,300 84,190 81,703 84,504 Earnings per share Basic $ 1.15 $ 0.97 $ 2.25 $ 1.86 Diluted $ 1.13 $ 0.95 $ 2.22 $ 1.83 Anti-dilutive shares 9 4 3 1

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We are a U.S. taxpayer and are subject to a statutory U.S. federal corporate income tax rate of 21%. Taxable income is reported on our consolidated U.S. federal and various state income tax returns, filed by NMIH on behalf of itself and its subsidiaries. Our effective tax rate on pre-tax income was 22.4% and 22.3% for the three and six months ended June 30, 2024, respectively, compared to 22.8% and 22.7% for the three and six months ended June 30, 2023, respectively. Our provision for income taxes for interim reporting periods is established based on our estimated annual effective tax rate for a given year. Our effective tax rate may fluctuate between interim periods due to the impact of discrete items not included in our estimated annual effective tax rate, including the tax effects associated with the vesting of RSUs and exercise of options. Such items are treated on a discrete basis in the reporting period in which they occur. As a mortgage guaranty insurance company, we are eligible to claim a tax deduction for our statutory contingency reserve balance, subject to certain limitations outlined under IRC Section 832(e), and only to the extent we acquire tax and loss bonds in an amount equal to the tax benefit derived from the claimed deduction, which is our intent. As a result, our interim provision for income taxes for the three and six months ended June 30, 2024 and 2023 primarily represents a change in our net deferred tax liability. As of June 30, 2024 and December 31, 2023, we held $235.3 million of tax and loss bonds in “Prepaid Federal Income Taxes” on our condensed consolidated balance sheets.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2024
Equity [Abstract]
Stockholders' Equity	Stockholders' Equity On February 10, 2022, our Board of Directors authorized a $125 million share repurchase program (excluding associated costs and applicable taxes) effective through December 31, 2023. On July 31, 2023, our Board of Directors authorized a new $200 million share repurchase program (excluding associated costs and applicable taxes) effective through December 31, 2025. Concurrent with the new authorization, our Board of Directors also approved an extension of our initial $125 million share repurchase program through December 31, 2025 to align its remaining tenor with that of the $200 million program. The authorization provides us the flexibility, based on market and business conditions, stock price and other factors, to repurchase stock from time to time through open market purchases, privately negotiated transactions, or other means, including pursuant to Rule 10b5-1 trading plans. During the six months ended June 30, 2024, we repurchased 1.7 million shares at an average price of $30.89 per share (excluding associated costs and applicable taxes). During the year ended December 31, 2023, we repurchased 3.5 million shares at an average price of $25.93 per share (excluding associated costs and applicable taxes). As of June 30, 2024, we had $124.9 million of repurchase authority remaining under our program.

Litigation

Litigation	6 Months Ended
	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Litigation	Litigation We record a litigation liability when we determine that it is probable a litigation loss will be incurred and the amount of such anticipated loss can be reasonably estimated. In the event we determine that a litigation loss is reasonably possible (though not probable), we disclose an estimate of the possible loss if such estimate can be reasonably established or disclose the matter with no estimate if such estimate cannot be reasonably made. We evaluate litigation and other legal developments that could affect our accrual for probable losses or our estimated disclosure of possible losses and make ongoing adjustments to our accruals and disclosures as appropriate. Significant judgment is required to determine both the likelihood and the estimated amount of potential losses related to such matters. We are currently named as a defendant in a litigation proceeding pertaining to the refund of certain mortgage insurance premiums under the Homeowners Protection Act. The case was dismissed in September 2023 and is currently pending appeal. We do not currently expect that we will incur a material loss in connection with the case and have not recorded a litigation liability for this matter.

Premiums Receivable

Premiums Receivable	6 Months Ended
	Jun. 30, 2024
Insurance [Abstract]
Premiums Receivable	Premiums Receivable Premiums receivable consists of premiums due on our mortgage insurance policies. If a mortgage insurance premium is unpaid for more than 120 days, the associated receivable is written off against earned premium and the related insurance policy is canceled. Premiums receivable may be written off prior to 120 days in the ordinary course of business for non-credit events including, but not limited to, the modification or refinancing of an underlying insured loan. We established a $2.2 million and $2.7 million reserve for premium write-offs at June 30, 2024 and December 31, 2023, respectively. We separately recognize an allowance for credit losses for premiums receivable based on credit losses expected to arise over the life of the receivable. Due to the nature of our insurance policies (a necessary precondition for access to mortgage credit for covered borrowers) and the short duration of the related receivables, we do not typically experience credit losses against our premium receivables and the allowance for credit loss established on premium receivable was deemed immaterial at June 30, 2024 and December 31, 2023.

Regulatory Information

Regulatory Information	6 Months Ended
	Jun. 30, 2024
Insurance [Abstract]
Regulatory Information	Regulatory Information Statutory Requirements Our insurance subsidiaries, NMIC and Re One, file financial statements in conformity with statutory accounting principles (SAP) prescribed or permitted by the Wisconsin OCI, NMIC's principal regulator. Prescribed SAP includes state laws, regulations and general administrative rules, as well as a variety of publications of the National Association of Insurance Commissioners (NAIC). The Wisconsin OCI recognizes only statutory accounting practices prescribed or permitted by the state of Wisconsin for determining and reporting the financial condition and results of operations of an insurance company and for determining its solvency under Wisconsin insurance laws. NMIC and Re One generated combined statutory net income of $36.0 million and $70.7 million for the three and six months ended June 30, 2024, respectively, compared to $28.1 million and $49.9 million for the three and six months ended June 30, 2023, respectively. The Wisconsin OCI has imposed a prescribed accounting practice for the treatment of statutory contingency reserves that differs from the treatment promulgated by the NAIC. Under Wisconsin OCI's prescribed practice mortgage guaranty insurers are required to reflect changes in their contingency reserves through statutory income. Such approach contrasts with the NAIC's treatment, which records changes to contingency reserves directly to unassigned funds. As a Wisconsin-domiciled insurer, NMIC's statutory net income reflects an expense associated with the change in its contingency reserve. While such treatment impacts NMIC's statutory net income, it does not have an effect on NMIC's statutory capital position. The following table presents NMIC's statutory surplus, contingency reserve, statutory capital and risk-to-capital (RTC) ratio as of June 30, 2024 and December 31, 2023. June 30, 2024 December 31, 2023 (In Thousands) Statutory surplus $ 932,419 $ 963,085 Contingency reserve 1,737,120 1,573,360 Statutory capital (1) $ 2,669,539 $ 2,536,445 Risk-to-capital 12.4:1 11.4:1 (1) Represents the total of the statutory surplus and contingency reserve. Re One had $2.1 million and $2.0 million of statutory capital at June 30, 2024 and December 31, 2023, respectively. NMIH is not subject to any limitations on its ability to pay dividends except those generally applicable to corporations that are incorporated in Delaware. Delaware law provides that dividends are only payable out of a corporation's capital surplus or, subject to certain limitations, recent net profits. NMIC and Re One are subject to certain rules and regulations prescribed by jurisdictions in which they are authorized to operate and the GSEs that may restrict their ability to pay dividends to NMIH. NMIC has the capacity to pay $96.3 million of aggregate ordinary dividends to NMIH during the twelve-month period ending December 31, 2024, and on May 30, 2024, NMIC paid a $96.3 million ordinary course dividend to NMIH.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Effective July 25, 2024, NMIC exercised its optional call to terminate the 2019 ILN Transaction. In connection with the termination of the transaction, NMIC’s excess of loss reinsurance agreement with Oaktown Re III Ltd. was commuted and the insurance-linked notes issued by Oaktown Re III Ltd. were redeemed in full with a distribution of remaining collateral assets.

Organization, Basis of Presen_2

Organization, Basis of Presentation and Summary of Accounting Principles (Policies)	6 Months Ended
	Jun. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements, which include the results of NMIH and its wholly-owned subsidiaries, have been prepared in accordance with the instructions to Form 10-Q as prescribed by the SEC for interim reporting and include other information and disclosures required by accounting principles generally accepted in the U.S. (GAAP). Our accounts are maintained in U.S. dollars. These statements should be read in conjunction with our consolidated financial statements and notes thereto for the year ended December 31, 2023, included in our 2023 10-K. All intercompany transactions have been eliminated. Certain reclassifications to previously reported financial information have been made to conform to our current period presentation. The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect reported amounts of assets and liabilities, as well as disclosure of contingent assets and liabilities as of the balance sheet date. Estimates also affect the reported amounts of income and expenses for the reporting period. Actual results could differ from those estimates. The results of operations for the interim period may not be indicative of the results that may be expected for the full year ending December 31, 2024.
Recent Accounting Pronouncements - Not Yet Adopted	Recent Accounting Pronouncements – Not Yet Adopted In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280). The update expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. The standard will take effect for all public business entities, including those that have only a single reportable segment for fiscal years beginning after December 15, 2023, and interim periods beginning after December 31, 2024. We are currently evaluating the impact the adoption of this ASU will have, if any, on our consolidated financial statements.
Fair Value of Financial Instruments	The following describes the valuation techniques used by us to determine the fair value of our financial instruments: We established a fair value hierarchy by prioritizing the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under this standard are described below: Level 1 - Fair value measurements based on quoted prices in active markets that we have the ability to access for identical assets or liabilities. Market price data generally is obtained from exchange or dealer markets. We do not adjust the quoted price for such instruments. Level 2 - Fair value measurements based on inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, and inputs other than quoted prices that are observable for the asset or liability, such as interest rates and yield curves that are observable at commonly quoted intervals. Level 3 - Fair value measurements based on valuation techniques that use significant inputs that are unobservable. Both observable and unobservable inputs may be used to determine the fair values of positions classified in Level 3. The circumstances for using these measurements include those in which there is little, if any, market activity for the asset or liability. Therefore, we must make certain assumptions, which require significant management judgment or estimation about the inputs a hypothetical market participant would use to value that asset or liability. In certain cases, the inputs used to measure fair value may fall into different levels of the fair value hierarchy. In such cases, the level in the fair value hierarchy is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Assets Classified as Level 1 and Level 2 To determine the fair value of securities available-for-sale in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources have been utilized. One price is provided per security based on observable market data. To ensure securities are appropriately classified in the fair value hierarchy, we review the pricing techniques and methodologies of the independent pricing sources and believe that their policies adequately consider market activity, either based on specific transactions for the issue valued or based on modeling of securities with similar credit quality, duration, yield and structure that were recently traded. A variety of inputs are utilized by the independent pricing sources including benchmark yields, reported trades, non-binding broker/dealer quotes, issuer spreads, two sided markets, benchmark securities, bids, offers and reference data including data published in market research publications. Inputs may be weighted differently for any security, and not all inputs are used for each security evaluation. Market indicators, industry and economic events are also considered. This information is evaluated using a multidimensional pricing model. Quality controls are performed by the independent pricing sources throughout this process, which include reviewing tolerance reports, trading information and data changes, and directional moves compared to market moves. This model combines all inputs to arrive at a value assigned to each security. We have not made any adjustments to the prices obtained from the independent pricing sources.
Earnings per Share (EPS)	Basic EPS is based on the weighted average number of shares of common stock outstanding. Diluted EPS is based on the weighted average number of shares of common stock outstanding and common stock equivalents that would be issuable upon the vesting of service-based and performance and service-based restricted stock units (RSUs), and the exercise of vested and unvested stock options.
Premiums Receivable	Premiums receivable consists of premiums due on our mortgage insurance policies. If a mortgage insurance premium is unpaid for more than 120 days, the associated receivable is written off against earned premium and the related insurance policy is canceled. Premiums receivable may be written off prior to 120 days in the ordinary course of business for non-credit events including, but not limited to, the modification or refinancing of an underlying insured loan. We established a $2.2 million and $2.7 million reserve for premium write-offs at June 30, 2024 and December 31, 2023, respectively. We separately recognize an allowance for credit losses for premiums receivable based on credit losses expected to arise over the life of the receivable. Due to the nature of our insurance policies (a necessary precondition for access to mortgage credit for covered borrowers) and the short duration of the related receivables, we do not typically experience credit losses against our premium receivables and the allowance for credit loss established on premium receivable was deemed immaterial at June 30, 2024 and December 31, 2023.

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of Fair Values and Gross Unrealized Gains and Losses	Fair Values and Gross Unrealized Gains and Losses on Investments Amortized Gross Unrealized Fair Gains Losses As of June 30, 2024 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 123,602 $ 1,149 $ (768) $ 123,983 Municipal debt securities 681,640 445 (59,469) 622,616 Corporate debt securities 1,767,760 2,083 (126,709) 1,643,134 Asset-backed securities 46,128 — (3,143) 42,985 Total bonds 2,619,130 3,677 (190,089) 2,432,718 Short-term investments 88,286 — (14) 88,272 Total investments $ 2,707,416 $ 3,677 $ (190,103) $ 2,520,990 Amortized Gross Unrealized Fair Gains Losses As of December 31, 2023 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 164,278 $ 3,374 $ (1,264) $ 166,388 Municipal debt securities 678,339 1,253 (58,462) 621,130 Corporate debt securities 1,624,187 7,868 (120,576) 1,511,479 Asset-backed securities 52,242 1 (4,032) 48,211 Total bonds 2,519,046 12,496 (184,334) 2,347,208 Short-term investments 23,816 2 (5) 23,813 Total investments $ 2,542,862 $ 12,498 $ (184,339) $ 2,371,021
Schedule of Corporate Debt Securities by Industry Group	The following table presents a breakdown of the fair value of our corporate debt securities by issuer industry group as of June 30, 2024 and December 31, 2023: June 30, 2024 December 31, 2023 Financial 35 % 35 % Consumer 27 26 Utilities 12 13 Industrial 10 9 Technology 8 8 Communications 8 9 Total 100 % 100 %
Schedule of Investments by Maturity	The amortized cost and fair value of available-for-sale securities as of June 30, 2024 and December 31, 2023, by contractual maturity, are shown below. Expected maturities will differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. Because most asset-backed securities provide for periodic payments throughout their lives, they are listed below in a separate category. As of June 30, 2024 Amortized Fair (In Thousands) Due in one year or less $ 216,476 $ 214,664 Due after one through five years 1,418,059 1,331,158 Due after five through ten years 986,357 892,216 Due after ten years 40,396 39,967 Asset-backed securities 46,128 42,985 Total investments $ 2,707,416 $ 2,520,990 As of December 31, 2023 Amortized Fair (In Thousands) Due in one year or less $ 191,375 $ 189,729 Due after one through five years 1,237,192 1,162,259 Due after five through ten years 1,050,989 959,633 Due after ten years 11,064 11,189 Asset-backed securities 52,242 48,211 Total investments $ 2,542,862 $ 2,371,021
Schedule of Aging Unrealized Losses	For those securities in an unrealized loss position, the length of time the securities were in such a position is as follows: Less Than Twelve Months Twelve Months or Greater Total # of Securities Fair Value Unrealized Losses # of Securities Fair Value Unrealized Losses # of Securities Fair Value Unrealized Losses As of June 30, 2024 ($ In Thousands) U.S. Treasury securities and obligations of U.S. government agencies 4 $ 12,598 $ (31) 11 $ 21,274 $ (737) 15 $ 33,872 $ (768) Municipal debt securities 22 114,419 (1,825) 223 484,737 (57,644) 245 599,156 (59,469) Corporate debt securities 52 305,550 (3,413) 245 1,104,989 (123,296) 297 1,410,539 (126,709) Asset-backed securities 1 567 — 23 42,418 (3,143) 24 42,985 (3,143) Short-term investments 5 87,891 (14) — — — 5 87,891 (14) Total 84 $ 521,025 $ (5,283) 502 $ 1,653,418 $ (184,820) 586 $ 2,174,443 $ (190,103) Less Than Twelve Months Twelve Months or Greater Total # of Securities Fair Value Unrealized Losses # of Securities Fair Value Unrealized Losses # of Securities Fair Value Unrealized Losses As of December 31, 2023 ($ In Thousands) U.S. Treasury securities and obligations of U.S. government agencies 8 $ 5,022 $ (62) 17 $ 72,003 $ (1,202) 25 $ 77,025 $ (1,264) Municipal debt securities 14 56,280 (502) 217 467,098 (57,960) 231 523,378 (58,462) Corporate debt securities 13 56,039 (705) 266 1,150,662 (119,871) 279 1,206,701 (120,576) Asset-backed securities — — — 23 47,426 (4,032) 23 47,426 (4,032) Short-term investments 1 9,925 (5) — — — 1 9,925 (5) Total 36 $ 127,266 $ (1,274) 523 $ 1,737,189 $ (183,065) 559 $ 1,864,455 $ (184,339)
Schedule of Net Investment Income	The following table presents the components of net investment income: For the three months ended June 30, For the six months ended June 30, 2024 2023 2024 2023 (In Thousands) Investment income (1) $ 20,954 $ 16,591 $ 40,651 $ 31,765 Investment expenses (266) (73) (527) (353) Net investment income $ 20,688 $ 16,518 $ 40,124 $ 31,412 (1) Includes interest income recognized on cash and cash equivalents of $1.8 million and $2.9 million during the three and six months ended June 30, 2024, respectively, and $0.4 million and $0.7 million during the three and six months ended June 30, 2023, respectively.
Schedule of Net Realized Investment Losses	The following table presents the components of net realized investment losses: For the three months ended June 30, For the six months ended June 30, 2024 2023 2024 2023 (In Thousands) Gross realized investment gains $ — $ — $ — $ — Gross realized investment losses — — — (33) Net realized investment losses $ — $ — $ — $ (33)

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Fair Value Measurements of Financial Instruments	The following tables present the level within the fair value hierarchy at which our financial instruments were measured: Fair Value Measurements Using Quoted Prices in Significant Other Significant Fair Value As of June 30, 2024 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 123,983 $ — $ — $ 123,983 Municipal debt securities — 622,616 — 622,616 Corporate debt securities — 1,643,134 — 1,643,134 Asset-backed securities — 42,985 — 42,985 Cash, cash equivalents and short-term investments 150,901 — — 150,901 Total assets $ 274,884 $ 2,308,735 $ — $ 2,583,619 Fair Value Measurements Using Quoted Prices in Significant Other Significant Fair Value As of December 31, 2023 (In Thousands) U.S. Treasury securities and obligations of U.S. government agencies $ 166,388 $ — $ — $ 166,388 Municipal debt securities — 621,130 — 621,130 Corporate debt securities — 1,511,479 — 1,511,479 Asset-backed securities — 48,211 — 48,211 Cash, cash equivalents and short-term investments 120,502 — — 120,502 Total assets $ 286,890 $ 2,180,820 $ — $ 2,467,710

Reinsurance (Tables)

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2024
Reinsurance Disclosures [Abstract]
Schedule of Effect of Reinsurance Agreements on Premiums Written and Earned	The effect of our reinsurance agreements on premiums written and earned is as follows: For the three months ended June 30, For the six months ended June 30, 2024 2023 2024 2023 (In Thousands) Net premiums written Direct $ 166,183 $ 151,992 $ 329,390 $ 300,924 Ceded (1) (32,369) (34,848) (65,331) (70,804) Net premiums written $ 133,814 $ 117,144 $ 264,059 $ 230,120 Net premiums earned Direct $ 173,633 $ 160,988 $ 343,351 $ 318,892 Ceded (1) (32,465) (35,003) (65,526) (71,153) Net premiums earned $ 141,168 $ 125,985 $ 277,825 $ 247,739 (1) Net of profit commission. The following table shows amounts related to the QSR Transactions: As of and for the three months ended As of and for the six months ended June 30, 2024 June 30, 2023 June 30, 2024 June 30, 2023 (In Thousands) Ceded risk-in-force $ 12,815,434 $ 12,761,294 $ 12,815,434 $ 12,761,294 Ceded premiums earned (41,555) (42,002) (82,824) (84,098) Ceded claims and claim (benefits) expenses (138) 803 521 2,768 Ceding commission earned 10,222 9,877 20,514 19,842 Profit commission 24,351 23,486 47,758 45,765
Schedule of ILN Transactions	The following table presents the inception date, covered production period, initial and current reinsurance coverage amount, and initial and current first layer retained aggregate loss under each outstanding ILN Transaction. Current amounts are presented as of June 30, 2024. ( $ values in thousands) Inception Date Covered Production Initial Reinsurance Coverage Current Reinsurance Coverage Initial First Layer Retained Loss Current First Layer Retained Loss (1) 2019 ILN Transaction July 30, 2019 6/1/2018 – 6/30/2019 $ 326,905 $ 143,430 $ 123,424 $ 121,588 2020-2 ILN Transaction October 29, 2020 4/1/2020 – 9/30/2020 (2) 242,351 37,165 121,777 121,015 2021-1 ILN Transaction April 27, 2021 10/1/2020 – 3/31/2021 (3) 367,238 180,516 163,708 163,321 2021-2 ILN Transaction October 26, 2021 4/1/2021 – 9/30/2021 (4) 363,596 273,706 146,229 145,549 (1) NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure and cedes reserves for incurred claims and claim expenses to each applicable ILN Transaction and recognizes a reinsurance recoverable if such incurred claims and claim expenses exceed its current first layer retained loss. (2) Approximately 1% of the production covered by the 2020-2 ILN Transaction has coverage reporting dates between July 1, 2019 and March 31, 2020. (3) Approximately 1% of the production covered by the 2021-1 ILN Transaction has coverage reporting dates between July 1, 2019 and September 30, 2020. (4) Approximately 2% of the production covered by the 2021-2 ILN Transaction has coverage reporting dates between July 1, 2019 and March 31, 2021.
Schedule of XOL Transactions	The following table presents the inception date, covered production period, initial and current reinsurance coverage amount, and initial and current first layer retained aggregate loss under each outstanding XOL Transaction. Current amounts are presented as of June 30, 2024. ($ values in thousands) Inception Date Covered Production Initial Reinsurance Coverage Current Reinsurance Coverage Initial First Layer Retained Loss Current First Layer Retained Loss (1) 2022-1 XOL Transaction April 1, 2022 10/1/2021 – 3/31/2022 (2) $ 289,741 $ 213,416 $ 133,366 $ 132,863 2022-2 XOL Transaction July 1, 2022 4/1/2022 – 6/30/2022 (3) 154,306 135,669 78,906 78,518 2022-3 XOL Transaction October 1, 2022 7/1/2022 – 9/30/2022 96,779 96,197 106,265 105,961 2023-1 XOL Transaction January 1, 2023 10/1/2022 – 6/30/2023 89,864 88,351 146,513 146,218 2023-2 XOL Transaction July 1, 2023 7/1/2023 – 12/31/2023 100,777 100,777 136,875 136,875 2024 XOL Transaction (4) January 1, 2024 1/1/2024 – 12/31/2024 86,477 86,477 151,609 151,609 (1) NMIC applies claims paid on covered policies against its first layer aggregate retained loss exposure and cedes reserves for incurred claims and claim expenses to each applicable XOL Transaction and recognizes a reinsurance recoverable if such incurred claims and claim expenses exceed its current first layer retained loss. (2) Approximately 1% of the production covered by the 2022-1 XOL Transaction has coverage reporting dates between October 21, 2019 and September 30, 2021. (3) Approximately 1% of the production covered by the 2022-2 XOL Transaction has coverage reporting dates between January 4, 2021 and March 31, 2022. (4) The initial reinsurance coverage, current reinsurance coverage, initial first layer retained loss and current first layer retained loss for the 2024 XOL Transaction will increase as incremental covered production is ceded under the transaction through December 31, 2024.

Reserves for Insurance Claims_2

Reserves for Insurance Claims and Claim Expenses (Tables)	6 Months Ended
	Jun. 30, 2024
Insurance [Abstract]
Schedule of Reconciliation of Liability for Insurance Claims and (benefits) Claim Expenses	The following table provides a reconciliation of the beginning and ending gross reserve balances for primary insurance claims and claim expenses: For the six months ended June 30, 2024 2023 (In Thousands) Beginning balance $ 123,974 $ 99,836 Less reinsurance recoverables (1) (27,514) (21,587) Beginning balance, net of reinsurance recoverables 96,460 78,249 Add claims incurred: Claims and claim expenses incurred: Current year (2) 50,372 44,870 Prior years (3) (46,402) (35,296) Total claims and claim expenses incurred 3,970 9,574 Less claims paid: Claims and claim expenses paid: Current year (2) — 54 Prior years (3) 2,323 1,344 Total claims and claim expenses paid 2,323 1,398 Reserve at end of period, net of reinsurance recoverables 98,107 86,425 Add reinsurance recoverables (1) 27,336 24,023 Ending balance $ 125,443 $ 110,448 (1) Related to ceded losses recoverable under the QSR Transactions. See Note 5, “ Reinsurance” for additional information. (2) Related to insured loans with their most recent defaults occurring in the current year. For example, if a loan defaulted in a prior year and subsequently cured and later re-defaulted in the current year, the default would be included in the current year. Amounts are presented net of reinsurance and included $43.1 million attributed to net case reserves and $6.4 million attributed to net IBNR reserves for the six months ended June 30, 2024 and $39.1 million attributed to net case reserves and $5.0 million attributed to net IBNR reserves for the six months ended June 30, 2023. (3) Related to insured loans with defaults occurring in prior years, which have been continuously in default before the start of the current year. Amounts are presented net of reinsurance and included $39.2 million attributed to net case reserves and $6.3 million attributed to net IBNR reserves for the six months ended June 30, 2024 and $30.3 million attributed to net case reserves and $4.5 million attributed to net IBNR reserves for the six months ended June 30, 2023.

Earnings per Share (EPS) (Table

Earnings per Share (EPS) (Tables)	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table reconciles the net income and the weighted average shares of common stock outstanding used in the computations of basic and diluted EPS of common stock: For the three months ended June 30, For the six months ended June 30, 2024 2023 2024 2023 (In Thousands, except for per share data) Net income – basic and diluted $ 92,079 $ 80,284 $ 181,129 $ 154,742 Basic weighted average shares outstanding 80,117 82,958 80,421 83,277 Dilutive effect of issuable shares 1,183 1,232 1,282 1,227 Diluted weighted average shares outstanding 81,300 84,190 81,703 84,504 Earnings per share Basic $ 1.15 $ 0.97 $ 2.25 $ 1.86 Diluted $ 1.13 $ 0.95 $ 2.22 $ 1.83 Anti-dilutive shares 9 4 3 1

Regulatory Information (Tables)

Regulatory Information (Tables)	6 Months Ended
	Jun. 30, 2024
Insurance [Abstract]
Schedule of Statutory Net Income (loss), Surplus, Contingency Reserve and Risk-to-Capital Ratio	The following table presents NMIC's statutory surplus, contingency reserve, statutory capital and risk-to-capital (RTC) ratio as of June 30, 2024 and December 31, 2023. June 30, 2024 December 31, 2023 (In Thousands) Statutory surplus $ 932,419 $ 963,085 Contingency reserve 1,737,120 1,573,360 Statutory capital (1) $ 2,669,539 $ 2,536,445 Risk-to-capital 12.4:1 11.4:1 (1) Represents the total of the statutory surplus and contingency reserve.

Organization, Basis of Presen_3

Organization, Basis of Presentation and Summary of Accounting Principles - Narrative (Details)	Jun. 30, 2024 state
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of states in which the entity operates	50

Investments - Schedule of Fair

Investments - Schedule of Fair Values and Gross Unrealized Gains and Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,707,416	$ 2,542,862
Gross unrealized gains	3,677	12,498
Gross unrealized losses	(190,103)	(184,339)
Fair Value	2,520,990	2,371,021
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	123,602	164,278
Gross unrealized gains	1,149	3,374
Gross unrealized losses	(768)	(1,264)
Fair Value	123,983	166,388
Municipal debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	681,640	678,339
Gross unrealized gains	445	1,253
Gross unrealized losses	(59,469)	(58,462)
Fair Value	622,616	621,130
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,767,760	1,624,187
Gross unrealized gains	2,083	7,868
Gross unrealized losses	(126,709)	(120,576)
Fair Value	1,643,134	1,511,479
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	46,128	52,242
Gross unrealized gains	0	1
Gross unrealized losses	(3,143)	(4,032)
Fair Value	42,985	48,211
Total bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,619,130	2,519,046
Gross unrealized gains	3,677	12,496
Gross unrealized losses	(190,089)	(184,334)
Fair Value	2,432,718	2,347,208
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	88,286	23,816
Gross unrealized gains	0	2
Gross unrealized losses	(14)	(5)
Fair Value	$ 88,272	$ 23,813

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Unsettled trade receivables	$ 43,000	$ 0
Unsettled trade payables		0
Unrealized loss position, accumulated loss	190,103	184,339
Unrealized loss position, 12 months or greater	184,820	183,065
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Cash and investments held with various state insurance departments	5,300	5,300
Unrealized loss position, accumulated loss	768	1,264
Unrealized loss position, 12 months or greater	$ 737	$ 1,202

Investments - Schedule of Corpo

Investments - Schedule of Corporate Debt Securities by Industry Group (Details)	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	100%	100%
Financial
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	35%	35%
Consumer
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	27%	26%
Utilities
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	12%	13%
Industrial
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	10%	9%
Technology
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	8%	8%
Communications
Debt Securities, Available-for-sale [Line Items]
Corporate debt securities as component of total (percent)	8%	9%

Investments - Schedule of Inves

Investments - Schedule of Investments by Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Amortized Cost
Due in one year or less	$ 216,476	$ 191,375
Due after one through five years	1,418,059	1,237,192
Due after five through ten years	986,357	1,050,989
Due after ten years	40,396	11,064
Asset-backed securities	46,128	52,242
Amortized Cost	2,707,416	2,542,862
Fair Value
Due in one year or less	214,664	189,729
Due after one through five years	1,331,158	1,162,259
Due after five through ten years	892,216	959,633
Due after ten years	39,967	11,189
Asset-backed securities	42,985	48,211
Fair Value	$ 2,520,990	$ 2,371,021

Investments - Schedule of Aging

Investments - Schedule of Aging of Unrealized Losses (Details) $ in Thousands	Jun. 30, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	84	36
Fair value, less than 12 months	$ 521,025	$ 127,266
Unrealized losses, less than 12 months	$ (5,283)	$ (1,274)
Number of securities,12 months or greater | security	502	523
Fair value, 12 months or greater	$ 1,653,418	$ 1,737,189
Unrealized losses, 12 months or greater	$ (184,820)	$ (183,065)
Number of securities, total | security	586	559
Fair Value	$ 2,174,443	$ 1,864,455
Unrealized Losses	$ (190,103)	$ (184,339)
U.S. Treasury securities and obligations of U.S. government agencies
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	4	8
Fair value, less than 12 months	$ 12,598	$ 5,022
Unrealized losses, less than 12 months	$ (31)	$ (62)
Number of securities,12 months or greater | security	11	17
Fair value, 12 months or greater	$ 21,274	$ 72,003
Unrealized losses, 12 months or greater	$ (737)	$ (1,202)
Number of securities, total | security	15	25
Fair Value	$ 33,872	$ 77,025
Unrealized Losses	$ (768)	$ (1,264)
Municipal debt securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	22	14
Fair value, less than 12 months	$ 114,419	$ 56,280
Unrealized losses, less than 12 months	$ (1,825)	$ (502)
Number of securities,12 months or greater | security	223	217
Fair value, 12 months or greater	$ 484,737	$ 467,098
Unrealized losses, 12 months or greater	$ (57,644)	$ (57,960)
Number of securities, total | security	245	231
Fair Value	$ 599,156	$ 523,378
Unrealized Losses	$ (59,469)	$ (58,462)
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	52	13
Fair value, less than 12 months	$ 305,550	$ 56,039
Unrealized losses, less than 12 months	$ (3,413)	$ (705)
Number of securities,12 months or greater | security	245	266
Fair value, 12 months or greater	$ 1,104,989	$ 1,150,662
Unrealized losses, 12 months or greater	$ (123,296)	$ (119,871)
Number of securities, total | security	297	279
Fair Value	$ 1,410,539	$ 1,206,701
Unrealized Losses	$ (126,709)	$ (120,576)
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	1	0
Fair value, less than 12 months	$ 567	$ 0
Unrealized losses, less than 12 months	$ 0	$ 0
Number of securities,12 months or greater | security	23	23
Fair value, 12 months or greater	$ 42,418	$ 47,426
Unrealized losses, 12 months or greater	$ (3,143)	$ (4,032)
Number of securities, total | security	24	23
Fair Value	$ 42,985	$ 47,426
Unrealized Losses	$ (3,143)	$ (4,032)
Short-term investments
Debt Securities, Available-for-sale [Line Items]
Number of securities, less than 12 months | security	5	1
Fair value, less than 12 months	$ 87,891	$ 9,925
Unrealized losses, less than 12 months	$ (14)	$ (5)
Number of securities,12 months or greater | security	0	0
Fair value, 12 months or greater	$ 0	$ 0
Unrealized losses, 12 months or greater	$ 0	$ 0
Number of securities, total | security	5	1
Fair Value	$ 87,891	$ 9,925
Unrealized Losses	$ (14)	$ (5)

Investments - Schedule of Net I

Investments - Schedule of Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Investment Income, Net [Abstract]
Investment income	$ 20,954	$ 16,591	$ 40,651	$ 31,765
Investment expenses	(266)	(73)	(527)	(353)
Net investment income	20,688	16,518	40,124	31,412
Cash and Cash Equivalents
Investment Income, Net [Abstract]
Investment income	$ 1,800	$ 400	$ 2,900	$ 700

Investments - Schedule of Net R

Investments - Schedule of Net Realized Investment Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Gross realized investment gains	$ 0	$ 0	$ 0	$ 0
Gross realized investment losses	0	0	0	(33)
Net realized investment losses	$ 0	$ 0	$ 0	$ (33)

Fair Value of Financial Instr_3

Fair Value of Financial Instruments -Schedule of Fair Value Measurements of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	$ 2,520,990	$ 2,371,021
U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	123,983	166,388
Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	622,616	621,130
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	1,643,134	1,511,479
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	42,985	48,211
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	150,901	120,502
Total assets	2,583,619	2,467,710
Recurring | U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	123,983	166,388
Recurring | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	622,616	621,130
Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	1,643,134	1,511,479
Recurring | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	42,985	48,211
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	150,901	120,502
Total assets	274,884	286,890
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	123,983	166,388
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	0	0
Total assets	2,308,735	2,180,820
Recurring | Significant Other Observable Inputs (Level 2) | U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	622,616	621,130
Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	1,643,134	1,511,479
Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	42,985	48,211
Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash, cash equivalents and short-term investments	0	0
Total assets	0	0
Recurring | Significant Unobservable Inputs (Level 3) | U.S. Treasury securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of securities	$ 0	$ 0

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Narrative (Details) - USD ($)	Jun. 30, 2024	May 21, 2024	Dec. 31, 2023
Senior 2024 Notes | Unsecured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument face amount		$ 425,000,000
Carried cost	$ 414,200,000
Unamortized debt issuance costs and original issuance discount	10,800,000	10,900,000
Senior 2024 Notes | Unsecured Debt | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long term debt	421,600,000
Senior 2020 Notes | Secured Debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument face amount		$ 400,000,000
Carried cost			$ 397,600,000
Unamortized debt issuance costs and original issuance discount	$ 2,400,000
Debt issuance costs			2,400,000
Senior 2020 Notes | Secured Debt | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long term debt			$ 401,900,000

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)			3 Months Ended	6 Months Ended
	May 21, 2024	Apr. 29, 2024	Jun. 30, 2024	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Debt Instrument [Line Items]
Loss on redemption of debt				$ 6,966,000	$ 0
Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fees in interest expense			$ 200,000	300,000
Unsecured Debt | On or After July 15, 2029
Debt Instrument [Line Items]
Redemption price (in percent)	100%
Senior Notes
Debt Instrument [Line Items]
Interest payable			2,800,000	2,800,000		$ 2,500,000
Senior 2024 Notes | Unsecured Debt
Debt Instrument [Line Items]
Senior notes			425,000,000	425,000,000
Stated interest rate (in percent)	6%
Original issuance discount	$ 10,900,000		10,800,000	10,800,000
Effective interest rate (in percent)	6.583%
Senior 2020 Notes | Secured Debt
Debt Instrument [Line Items]
Repayments of debt	$ 400,000,000
Original issuance discount			2,400,000	2,400,000
Loss on redemption of debt				6,800,000
2024 Revolving Credit Facility
Debt Instrument [Line Items]
Debt issuance costs		$ 2,100,000
2024 Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility borrowing capacity		$ 250,000,000
Debt instrument term (years)		5 years
Borrowings outstanding			0	$ 0		0
Commitment fee (in percent)				0.225%
Debt instrument covenant, maximum debt-to-total capitalization ratio				35%
2024 Revolving Credit Facility | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Commitment fee (in percent)		0.175%
2024 Revolving Credit Facility | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Commitment fee (in percent)		0.525%
2024 Revolving Credit Facility | Base rate | Revolving Credit Facility
Debt Instrument [Line Items]
Variable rate floor (in percent)		1%
2024 Revolving Credit Facility | Base rate | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)		0.375%
2024 Revolving Credit Facility | Base rate | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)		1.875%
2024 Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)		1.375%
2024 Revolving Credit Facility | Secured Overnight Financing Rate (SOFR) | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (in percent)		2.875%
2021 Revolving Credit Facility
Debt Instrument [Line Items]
Unamortized debt issuance cost		$ 600,000
2021 Revolving Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility borrowing capacity		$ 250,000,000
Debt instrument term (years)		4 years
Borrowings outstanding			0	$ 0		0
Remaining deferred issuance costs, net of accumulated amortization			$ 2,600,000	$ 2,600,000		$ 800,000

Reinsurance - Schedule of Effec

Reinsurance - Schedule of Effect of Reinsurance Agreements on Premiums Written and Earned (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Net premiums written
Direct	$ 166,183	$ 151,992	$ 329,390	$ 300,924
Ceded	(32,369)	(34,848)	(65,331)	(70,804)
Net premiums written	133,814	117,144	264,059	230,120
Net premiums earned
Direct	173,633	160,988	343,351	318,892
Ceded	(32,465)	(35,003)	(65,526)	(71,153)
Net premiums earned	$ 141,168	$ 125,985	$ 277,825	$ 247,739

Reinsurance - Narrative (Detail

Reinsurance - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) reinsuranceAgreement quota_share_agreement	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) reinsuranceAgreement quota_share_agreement	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Ceded Credit Risk [Line Items]
Reinsurance coverage amount amortized (as a percent)	10%		10%
Restricted cash	$ 1,152		$ 1,152		$ 1,338
Number of excess-of-loss reinsurance agreements | reinsuranceAgreement	6		6
Reinsurance coverage amount	$ 9,400	$ 7,700	$ 18,600	$ 14,900
Number of quota share reinsurance treaties | quota_share_agreement	8		8
Reinsurance recoverable on unpaid claims	$ 27,336	24,023	$ 27,336	24,023	27,514	$ 21,587
Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Reinsurance coverage, term of underlying mortgage amortization (in years)			10 years
Reinsurance Policy, Type [Axis]: QSR Transactions
Ceded Credit Risk [Line Items]
Reinsurance recoverable on unpaid claims	25,900		$ 25,900		25,800
Maximum | Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Reinsurance coverage, term of underlying mortgage amortization (in years)			12 years 6 months
Minimum
Ceded Credit Risk [Line Items]
Reinsurance coverage, term of underlying mortgage amortization (in years)			10 years
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: QSR Transactions
Ceded Credit Risk [Line Items]
Percentage of ceding commission received			20%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2016 QSR Transaction
Ceded Credit Risk [Line Items]
Threshold for loss ratio on loans to qualify for profit commission			60%
Reinsurance recoverable on unpaid claims	1,400		$ 1,400		$ 1,700
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2016 QSR Transaction, Eligible Primary Policies
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			20.50%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2016 QSR Transaction, Pool Agreement with Fannie Mae
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			100%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2018 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			25%
Threshold for loss ratio on loans to qualify for profit commission			61%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2019 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			20%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2020 Amended QSR Transaction
Ceded Credit Risk [Line Items]
Threshold for loss ratio on loans to qualify for profit commission			50%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2020 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			21%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2020 Seasoned QSR Transaction
Ceded Credit Risk [Line Items]
Percentage of ceding commission received			36%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2021 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			22.50%
Threshold for loss ratio on loans to qualify for profit commission			57.50%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2022 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			20%
Threshold for loss ratio on loans to qualify for profit commission			62%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2022 Seasoned QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			95%
Percentage of ceding commission received			35%
Threshold for loss ratio on loans to qualify for profit commission			55%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2023 QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			20%
Threshold for loss ratio on loans to qualify for profit commission			62%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: 2024 Seasoned QSR Transaction
Ceded Credit Risk [Line Items]
Percent of premiums earned under QSR Transaction			20%
Threshold for loss ratio on loans to qualify for profit commission			56%
Third-party Reinsurers | Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Risk premiums paid	$ 5,900	$ 8,800	$ 11,800	$ 17,900
Third-party Reinsurers | Maximum | Reinsurance Policy, Type [Axis]: Oaktown Re Vehicles
Ceded Credit Risk [Line Items]
Anticipated payment related to annual operating expenses			$ 250

Reinsurance - Schedule of ILN T

Reinsurance - Schedule of ILN Transactions and XOL Transactions (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Oct. 26, 2021	Apr. 27, 2021	Oct. 29, 2020	Jul. 30, 2019
Reinsurance Policy, Type [Axis]: 2019 ILN Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage					$ 326,905
Current Reinsurance Coverage	$ 143,430
Initial First Layer Retained Loss					$ 123,424
Current First Layer Retained Loss	$ 121,588
Reinsurance Policy, Type [Axis]: 2020-2 ILN
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of population with production prior to period start date	1%
Reinsurance Policy, Type [Axis]: 2020-2 ILN transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage				$ 242,351
Current Reinsurance Coverage	$ 37,165
Initial First Layer Retained Loss				$ 121,777
Current First Layer Retained Loss	$ 121,015
Reinsurance Policy, Type [Axis]: 2021-1 ILN
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of population with production prior to period start date	1%
Reinsurance Policy, Type [Axis]: 2021-1 ILN Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage			$ 367,238
Current Reinsurance Coverage	$ 180,516
Initial First Layer Retained Loss			$ 163,708
Current First Layer Retained Loss	$ 163,321
Reinsurance Policy, Type [Axis]: 2021-2 ILN
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage of population with production prior to period start date	2%
Reinsurance Policy, Type [Axis]: 2021-2 ILN Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage		$ 363,596
Current Reinsurance Coverage	$ 273,706
Initial First Layer Retained Loss		$ 146,229
Current First Layer Retained Loss	145,549
Reinsurance Policy, Type [Axis]: 2022-1 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	289,741
Current Reinsurance Coverage	213,416
Initial First Layer Retained Loss	133,366
Current First Layer Retained Loss	$ 132,863
Percentage of population with production prior to period start date	1%
Reinsurance Policy, Type [Axis]: 2022-2 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	$ 154,306
Current Reinsurance Coverage	135,669
Initial First Layer Retained Loss	78,906
Current First Layer Retained Loss	$ 78,518
Percentage of population with production prior to period start date	1%
Reinsurance Policy, Type [Axis]: 2022-3 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	$ 96,779
Current Reinsurance Coverage	96,197
Initial First Layer Retained Loss	106,265
Current First Layer Retained Loss	105,961
Reinsurance Policy, Type [Axis]: 2023-1 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	89,864
Current Reinsurance Coverage	88,351
Initial First Layer Retained Loss	146,513
Current First Layer Retained Loss	146,218
Reinsurance Policy, Type [Axis]: 2023-2 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	100,777
Current Reinsurance Coverage	100,777
Initial First Layer Retained Loss	136,875
Current First Layer Retained Loss	136,875
Reinsurance Policy, Type [Axis]: 2024 XOL Transaction
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Initial Reinsurance Coverage	86,477
Current Reinsurance Coverage	86,477
Initial First Layer Retained Loss	151,609
Current First Layer Retained Loss	$ 151,609

Reinsurance - Schedule of Amoun

Reinsurance - Schedule of Amounts Related to QSR Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Ceded Credit Risk [Line Items]
Ceded premiums earned	$ (32,465)	$ (35,003)	$ (65,526)	$ (71,153)
Third-party Reinsurers
Ceded Credit Risk [Line Items]
Ceded risk-in-force	12,815,434	12,761,294	12,815,434	12,761,294
Ceded premiums earned	(41,555)	(42,002)	(82,824)	(84,098)
Ceded claims and claim (benefits) expenses	(138)	803	521	2,768
Ceding commission earned	10,222	9,877	20,514	19,842
Profit commission	$ 24,351	$ 23,486	$ 47,758	$ 45,765

Reserves for Insurance Claims_3

Reserves for Insurance Claims and Claim Expenses - Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2024 USD ($) claim policy loan	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) loan policy	Dec. 31, 2022 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Total gross liability for unpaid claims and claim adjustment expenses	$ 125,443	$ 110,448	$ 123,974	$ 99,836
Number of claims paid | claim	101
Claims paid, including amounts covered by insurance	$ 3,000
Primary loans in default | loan	4,904		5,099
Primary insured portfolio, loan default rate	0.76%		0.81%
Total number of policies in-force | policy	645,276		629,690
Favorable development on prior year defaults	$ 46,400	$ 35,300
Reserve for prior year insurance claims and claim expenses	$ 61,400
Reinsurance Policy, Type [Axis]: QSR Transactions
Liability for Claims and Claims Adjustment Expense [Line Items]
Number of covered claims included in number of claims paid | claim | claim	97
Component of claims paid covered under QSR Transaction	$ 700

Reserves for Insurance Claims_4

Reserves for Insurance Claims and Claim Expenses - Reconciliation of Reserve Balances for Insurance Claims and Claim Expense (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning balance	$ 123,974	$ 99,836
Less reinsurance recoverables	(27,514)	(21,587)
Beginning balance, net of reinsurance recoverables	96,460	78,249
Claims and claim expenses incurred:
Current year	50,372	44,870
Prior years	(46,402)	(35,296)
Total claims and claim expenses incurred	3,970	9,574
Claims and claim expenses paid:
Current year	0	54
Prior years	2,323	1,344
Total claims and claim expenses paid	2,323	1,398
Reserve at end of period, net of reinsurance recoverables	98,107	86,425
Add reinsurance recoverables	27,336	24,023
Ending balance	125,443	110,448
Current year case reserves	43,100	39,100
Current year IBNR	6,400	5,000
Prior year case reserves	39,200	30,300
Prior year, IBNR	$ 6,300	$ 4,500

Earnings per Share (EPS) - Sche

Earnings per Share (EPS) - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Basic EPS
Net income - basic	$ 92,079	$ 80,284	$ 181,129	$ 154,742
Net income - diluted	$ 92,079	$ 80,284	$ 181,129	$ 154,742
Basic weighted average shares outstanding (in shares)	80,117	82,958	80,421	83,277
Dilutive effect of issuable shares (in shares)	1,183	1,232	1,282	1,227
Dilutive weighted average shares outstanding (in shares)	81,300	84,190	81,703	84,504
Basic earnings per share (in dollars per share)	$ 1.15	$ 0.97	$ 2.25	$ 1.86
Diluted earnings per share (in dollars per share)	$ 1.13	$ 0.95	$ 2.22	$ 1.83
Anti-dilutive shares (in shares)	9	4	3	1

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Effective income tax rate on pre-tax income or loss	22.40%	22.80%	22.30%	22.70%
Prepaid federal income taxes	$ 235,286		$ 235,286		$ 235,286

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023	Jul. 31, 2023	Feb. 10, 2022
Class of Stock [Line Items]
Repurchase authorization				$ 125,000,000
Repurchased shares (in shares)	1.7	3.5
Shares repurchased, average price per share (in dollars per share)	$ 30.89	$ 25.93
Remaining authorized repurchase amount	$ 124,900,000
July 2023 Share Repurchase Program
Class of Stock [Line Items]
Repurchase authorization			$ 200,000,000
2022 Extended Share Repurchase Program
Class of Stock [Line Items]
Repurchase authorization			$ 125,000,000

Premiums Receivable - Narrative

Premiums Receivable - Narrative (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2024 USD ($) d	Dec. 31, 2023 USD ($)
Insurance [Abstract]
Number of days to be written off | d	120
Premium receivable, write-off period	120 days
Premium receivable, allowance for credit loss, uncollected | $	$ 2.2	$ 2.7

Regulatory Information - Narrat

Regulatory Information - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	May 30, 2024	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
NMIC and Re One combined
Statutory Accounting Practices [Line Items]
Net income amount		$ 36,000	$ 28,100	$ 70,700	$ 49,900
Statutory capital		2,669,539		2,669,539		$ 2,536,445
Aggregate dividend capacity		96,300		96,300
Ordinary course dividend paid	$ 96,300
Re One
Statutory Accounting Practices [Line Items]
Statutory capital		$ 2,100		$ 2,100		$ 2,000

Regulatory Information - Schedu

Regulatory Information - Schedule of Statutory Net Income (loss), Surplus, Contingency Reserve and Risk-to-Capital Ratio (Details) - NMIC and Re One combined $ in Thousands	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Statutory Accounting Practices [Line Items]
Statutory surplus	$ 932,419	$ 963,085
Contingency reserve	1,737,120	1,573,360
Statutory capital	$ 2,669,539	$ 2,536,445
Risk-to-capital	12.4	11.4