XML 16 R6.htm IDEA: XBRL DOCUMENT
v3.19.2

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands | Total | Common Stock - Class A | Additional Paid-in Capital | Accumulated Other Comprehensive Income (Loss) | Retained Earnings
--- | --- | --- | --- | --- | ---
Beginning balance at Dec. 31, 2017 |  | $ 509,077 | $ 605 |  | $ 585,488 | $ (2,859) | $ (74,157)
Beginning balance (in shares) at Dec. 31, 2017 |  |  | 60,518,000 |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |
Common stock: class A shares issued related to public offering |  | 79,165 | $ 43 |  | 79,122 |  |
Common stock: class A shares issued related to public offering (in shares) |  |  | 4,255,000 |  |  |  |
Common stock: class A shares issued related to warrants | [1] | $ 489 |  |  | 489 |  |
Common stock: class A shares issued related to warrants (in shares) |  | 25,686 | 26,000 | [1] |  |  |
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes |  | $ (991) | $ 8 |  | (999) |  |
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares) |  |  | 770,000 |  |  |  |
Share-based compensation expense |  | 2,805 |  |  | 2,805 |  |
Change in unrealized investment gains/losses, net of tax |  | (10,956) |  |  |  | (10,956) |
Net income |  | 22,355 |  |  |  |  | 22,355
Ending balance at Mar. 31, 2018 |  | 601,944 | $ 656 |  | 666,905 | (13,533) | (52,084)
Ending balance (in shares) at Mar. 31, 2018 |  |  | 65,569,000 |  |  |  |
Beginning balance at Dec. 31, 2017 |  | $ 509,077 | $ 605 |  | 585,488 | (2,859) | (74,157)
Beginning balance (in shares) at Dec. 31, 2017 |  |  | 60,518,000 |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |
Common stock: class A shares issued related to warrants (in shares) |  | 29,000 |  |  |  |  |
Net income |  | $ 47,596 |  |  |  |  |
Ending balance at Jun. 30, 2018 |  | 629,642 | $ 658 |  | 670,870 | (15,043) | (26,843)
Ending balance (in shares) at Jun. 30, 2018 |  |  | 65,754,000 |  |  |  |
Beginning balance at Mar. 31, 2018 |  | 601,944 | $ 656 |  | 666,905 | (13,533) | (52,084)
Beginning balance (in shares) at Mar. 31, 2018 |  |  | 65,569,000 |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |
Common stock: class A shares issued related to warrants | [1] | $ 63 |  |  | 63 |  |
Common stock: class A shares issued related to warrants (in shares) |  | 3,751 | 3,000 | [1] |  |  |
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes |  | $ 887 | $ 2 |  | 885 |  |
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares) |  |  | 182,000 |  |  |  |
Share-based compensation expense |  | 3,017 |  |  | 3,017 |  |
Change in unrealized investment gains/losses, net of tax |  | (1,510) |  |  |  | (1,510) |
Net income |  | 25,241 |  |  |  |  | 25,241
Ending balance at Jun. 30, 2018 |  | 629,642 | $ 658 |  | 670,870 | (15,043) | (26,843)
Ending balance (in shares) at Jun. 30, 2018 |  |  | 65,754,000 |  |  |  |
Beginning balance at Dec. 31, 2018 |  | 701,500 | $ 663 |  | 682,181 | (14,832) | 33,488
Beginning balance (in shares) at Dec. 31, 2018 |  |  | 66,319,000 |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |
Common stock: class A shares issued related to warrants | [2] | $ 944 |  |  | 944 |  |
Common stock: class A shares issued related to warrants (in shares) |  | 39,195 | 39,000 | [2] |  |  |
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes |  | $ (1,459) | $ 12 |  | (1,471) |  |
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares) |  |  | 1,144,000 |  |  |  |
Share-based compensation expense |  | 2,981 |  |  | 2,981 |  |
Change in unrealized investment gains/losses, net of tax |  | 15,016 |  |  |  | 15,016 |
Net income |  | 32,899 |  |  |  |  | 32,899
Ending balance at Mar. 31, 2019 |  | 751,881 | $ 675 |  | 684,635 | 184 | 66,387
Ending balance (in shares) at Mar. 31, 2019 |  |  | 67,502,000 |  |  |  |
Beginning balance at Dec. 31, 2018 |  | $ 701,500 | $ 663 |  | 682,181 | (14,832) | 33,488
Beginning balance (in shares) at Dec. 31, 2018 |  |  | 66,319,000 |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |
Common stock: class A shares issued related to warrants (in shares) |  | 168,000 |  |  |  |  |
Net income |  | $ 71,999 |  |  |  |  |
Ending balance at Jun. 30, 2019 |  | 812,379 | $ 677 |  | 692,163 | 14,052 | 105,487
Ending balance (in shares) at Jun. 30, 2019 |  |  | 67,768,000 |  |  |  |
Beginning balance at Mar. 31, 2019 |  | 751,881 | $ 675 |  | 684,635 | 184 | 66,387
Beginning balance (in shares) at Mar. 31, 2019 |  |  | 67,502,000 |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |  |
Common stock: class A shares issued related to warrants |  | 3,836 | $ 1 |  | 3,835 |  |
Common stock: class A shares issued related to warrants (in shares) |  |  | 128,000 |  |  |  |
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes |  | 219 | $ 1 |  | 218 |  |
Common stock: class A shares issued under stock plans, net of shares withheld for employee taxes (in shares) |  |  | 138,000 |  |  |  |
Share-based compensation expense |  | 3,475 |  |  | 3,475 |  |
Change in unrealized investment gains/losses, net of tax |  | 13,868 |  |  |  | 13,868 |
Net income |  | 39,100 |  |  |  |  | 39,100
Ending balance at Jun. 30, 2019 |  | $ 812,379 | $ 677 |  | $ 692,163 | $ 14,052 | $ 105,487
Ending balance (in shares) at Jun. 30, 2019 |  |  | 67,768,000 |  |  |  |
[1] | During the three months ended March 31, 2018 and June 30, 2018, we issued 25,686 and 3,751 common shares, respectively, with a par value of $0.01 related to the exercise of warrants, which is not identifiable in this schedule due to rounding.
[2] | During the three months ended March 31, 2019, we issued 39,195 common shares with a par value of $0.01 related to the exercise of warrants, which is not identifiable in this schedule due to rounding.

X
- Definition Stock Issued During Period, Shares, Employee Stock Purchase Plans, Net of Shares For Tax Withholdings + References No definition available. + Details
Name: | nmih_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlansNetofSharesForTaxWithholdings
Namespace Prefix: | nmih_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Stock Issued During Period, Value, Employee Stock Purchase Plan, Net of Tax Withholdings + References No definition available. + Details
Name: | nmih_StockIssuedDuringPeriodValueEmployeeStockPurchasePlanNetofTaxWithholdings
Namespace Prefix: | nmih_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase to additional paid-in capital (APIC) for recognition of cost for award under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 20 -Section 55 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=118258462&loc=d3e11149-113907 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 20 -Section 55 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=118258462&loc=d3e11178-113907 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 35 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=116855982&loc=d3e4534-113899 + Details
Name: | us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_IncreaseDecreaseInStockholdersEquityRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(22)) -URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(18)) -URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(20)) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
Name: | us-gaap_NetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e637-108580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669646-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of shares issued which are neither cancelled nor held in the treasury. + References No definition available. + Details
Name: | us-gaap_SharesOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of shares issued during the period as a result of the conversion of convertible securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29-30) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of new stock issued during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The gross value of stock issued during the period upon the conversion of convertible securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.29-31) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 4.E) -URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74512-122707 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(31)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(30)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockholdersEquity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant