Mizuho Financial (MFG) 20-F 2 Jul 20 2020 FY Annual report (foreign) Financial data

Cover Page

Cover Page	12 Months Ended
	Mar. 31, 2020shares
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	MIZUHO FINANCIAL GROUP INC
Entity Central Index Key	0001335730
Current Fiscal Year End Date	--03-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Document Annual Report	true
Document Transition Report	false
Document Shell Company Report	false
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding	25,392,498,945
Document Accounting Standard	U.S. GAAP
Entity File Number	001-33098
Entity Incorporation, State or Country Code	M0
Document Registration Statement	false
Entity Address, Address Line One	1-5-5 Otemachi
Entity Address, City or Town	Chiyoda-ku
Entity Address, Postal Zip Code	100-8176
Entity Address, Country	JP
Business Contact [Member]
Document Information [Line Items]
Contact Personnel Name	Tomomichi Fujita
Entity Address, Address Line One	1-5-5 Otemachi
Entity Address, City or Town	Chiyoda-ku
Entity Address, Postal Zip Code	100-8176
Entity Address, Country	JP
City Area Code	81-3
Local Phone Number	5224-1111
American depositary shares
Document Information [Line Items]
Security Exchange Name	NYSE
Title of 12(b) Security	American depositary shares, each of which represents two shares of common stock
Trading Symbol	MFG
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, without par value
No Trading Symbol Flag	true

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Assets:
Cash and due from banks	¥ 2,325,139	¥ 1,404,008
Interest-bearing deposits in other banks	39,625,975	44,268,731
Call loans and funds sold	1,006,991	763,453
Receivables under resale agreements	18,580,919	12,997,424
Receivables under securities borrowing transactions	2,216,059	2,578,134
Trading account assets	28,092,871	21,018,230
Investments (Note 3):
Available-for-sale securities (including assets pledged that secured parties are permitted to sell or repledge of ¥1,132,602 million in 2019 and ¥1,036,534 million in 2020)	19,112,952	18,133,916
Held-to-maturity securities (including assets pledged that secured parties are permitted to sell or repledge of ¥476,146 million in 2019 and ¥297,240 million in 2020)	862,031	1,604,104
Equity securities	3,256,717	4,034,609
Other investments	443,951	389,740
Loans (Notes 4 and 5)	87,528,088	82,799,943
Allowance for loan losses	(440,855)	(307,201)
Loans, net of allowance	87,087,233	82,492,742
Premises and equipment—net (Note 6)	1,856,248	1,900,952
Due from customers on acceptances	167,764	187,137
Accrued income	323,632	342,845
Goodwill (Note 7)	92,997	95,151
Intangible assets (Note 7)	64,689	74,240
Deferred tax assets	136,713	49,775
Other assets (Note 12)	5,965,879	5,276,004
Total assets	211,218,760	197,611,195
Liabilities and equity:
Noninterest-bearing deposits	28,109,943	23,844,639
Interest-bearing deposits	86,651,036	84,019,038
Noninterest-bearing deposits	2,186,203	1,793,803
Interest-bearing deposits	28,001,485	28,639,436
Due to trust accounts	249,737	312,347
Call money and funds purchased	2,263,076	2,841,932
Payables under repurchase agreements (Note 29)	17,970,662	14,640,369
Payables under securities lending transactions (Note 29)	1,423,638	1,797,737
Other short-term borrowings (Note 11)	4,914,485	1,994,826
Trading account liabilities	12,416,785	10,120,968
Bank acceptances outstanding	167,764	187,137
Income taxes payable	68,557	58,688
Deferred tax liabilities	25,874	108,120
Accrued expenses	249,344	288,556
Long-term debt	10,346,152	11,529,400
Other liabilities (Note 12)	6,998,395	5,932,706
Total	202,043,136	188,109,702
Commitments and contingencies (Note 23)
MHFG shareholders' equity:
Common stock (Note 14)—no par value, authorized 48,000,000,000 shares in 2019 and 2020, and issued 25,392,498,945 shares in 2019 and 2020	5,827,500	5,829,657
Retained earnings	2,700,774	2,740,545
Accumulated other comprehensive income (loss), net of tax (Note 16)	(9,494)	164,021
Less: Treasury stock, at cost—Common stock 33,962,404 shares in 2019, and 32,106,811 shares in 2020	(6,415)	(7,704)
Total MHFG shareholders' equity	8,512,365	8,726,519
Noncontrolling interests	663,259	774,974
Total equity	9,175,624	9,501,493
Total liabilities and equity	211,218,760	197,611,195
Consolidated VIEs
Assets:
Cash and due from banks	8,749	29,972
Interest-bearing deposits in other banks	61,439	31,676
Call loans and funds sold	422,304	115,199
Trading account assets	2,438,607	2,456,198
Investments (Note 3):
Investments	62,262	52,493
Loans, net of allowance	2,285,831	2,359,669
Other assets (Note 12)	535,954	1,003,133
Total assets	5,815,146	6,048,340
Liabilities and equity:
Payables under securities lending transactions (Note 29)	138,094	108,038
Other short-term borrowings (Note 11)	60,086	23,495
Trading account liabilities	34,205
Long-term debt	330,863	344,526
Other liabilities (Note 12)	948,715	1,523,791
Total	¥ 1,511,963	¥ 1,999,850

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Trading account assets, assets pledged that secured parties are permitted to sell or repledge	¥ 4,978,497	¥ 3,244,305
Available-for-sale securities, assets pledged that secured parties are permitted to sell or repledge	1,036,534	1,132,602
Held-to-maturity securities, assets pledged that secured parties are permitted to sell or repledge	297,240	476,146
Long-term debt, liabilities accounted for at fair value	¥ 2,537,082	¥ 2,433,294
Common stock, par value	¥ 0	¥ 0
Common stock, authorized	48,000,000,000	48,000,000,000
Common stock, issued	25,392,498,945	25,392,498,945
Treasury stock, shares	32,106,811	33,962,404

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Interest and dividend income:
Loans, including fees		¥ 1,380,828	¥ 1,381,553	¥ 1,109,776
Investments:
Interest		89,749	144,199	88,319
Dividends		76,150	88,289	86,066
Trading account assets		221,983	211,749	202,125
Call loans and funds sold		5,434	5,547	5,699
Receivables under resale agreements and securities borrowing transactions		271,598	254,862	149,197
Deposits in other banks		105,430	121,244	120,704
Total interest and dividend income		2,151,172	2,207,443	1,761,886
Interest expense:
Deposits		615,785	613,570	382,706
Trading account liabilities		52,955	49,660	41,514
Call money and funds purchased		8,830	11,121	5,031
Payables under repurchase agreements and securities lending transactions		358,862	382,045	243,569
Other short-term borrowings		29,813	33,313	16,166
Long-term debt		205,136	223,767	200,950
Total interest expense		1,271,381	1,313,476	889,936
Net interest income		879,791	893,967	871,950
Provision (credit) for loan losses (Note 5)		156,200	32,459	(126,362)
Net interest income after provision (credit) for loan losses		723,591	861,508	998,312
Noninterest income (Note 25):
Fee and commission income		867,885	853,290	865,711
Foreign exchange gains (losses)—net	[1],[2]	44,345	93,577	91,793
Trading account gains (losses)—net	[3]	745,692	328,841	236,982
Investment gains (losses)—net:
Debt securities	[2]	31,032	(3,842)	7,757
Equity securities	[2]	(557,391)	(155,947)	289,400
Equity in earnings (losses) of equity method investees—net	[2]	34,012	29,172	24,342
Gains on disposal of premises and equipment	[2]	2,583	5,145	8,225
Other noninterest income	[3],[4]	139,582	72,135	80,453
Total noninterest income		1,307,740	1,222,371	1,604,663
Noninterest expenses:
Salaries and employee benefits		677,332	682,645	688,481
General and administrative expenses		649,498	761,528	585,992
Occupancy expenses		214,851	207,814	191,592
Fee and commission expenses		194,010	189,722	189,187
Provision (credit) for losses on off-balance-sheet instruments		19,262	(8,969)	(30,244)
Other noninterest expenses		122,888	166,079	138,669
Total noninterest expenses		1,877,841	1,998,819	1,763,677
Income before income tax expense		153,490	85,060	839,298
Income tax expense (Note 19)		47,175	9,335	237,604
Net income		106,315	75,725	601,694
Less: Net income (loss) attributable to noncontrolling interests		(43,880)	(8,746)	24,086
Net income attributable to MHFG shareholders		¥ 150,195	¥ 84,471	¥ 577,608
Earnings per common share (Note 18):
Basic net income per common share		¥ 5.92	¥ 3.33	¥ 22.77
Diluted net income per common share	[5]	5.92	3.33	22.76
Dividends Per Share [Abstract]
Class XI preferred stock		0
Common stock		¥ 7.50	¥ 7.50	¥ 7.50
[1]	Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.
[2]	These amounts are revenues from contracts that do not meet the scope of ASC 606.
[3]	Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606.
[4]	These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 27 “Fair value” for further details.
[5]	For the fiscal year ended March 31, 2020, the performance-based plan under the stock compensation programs could potentially dilute earnings per common share but were not included in the computation of diluted earnings per common share due to their antidilutive effects.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Net income	¥ 106,315	¥ 75,725	¥ 601,694
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on available-for-sale securities, net of tax	(41,483)	(9,472)	97,428
Foreign currency translation adjustments, net of tax	(50,576)	(23,781)	(29,934)
Pension liability adjustments, net of tax	(126,915)	(24,168)	155,044
Own credit risk adjustments, net of tax	46,919	14,476
Total other comprehensive income (loss), net of tax	(172,055)	(42,945)	222,538
Total comprehensive income (loss)	(65,740)	32,780	824,232
Less: Total comprehensive income attributable to noncontrolling interests	(43,472)	(8,960)	25,893
Total comprehensive income (loss) attributable to MHFG shareholders	¥ (22,268)	¥ 41,740	¥ 798,339

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - JPY (¥) ¥ in Millions	Total	Common Stock	Retained Earnings	Accumulated other comprehensive income (loss)		Treasury Stock	Parent	Noncontrolling Interest
Balance at beginning of fiscal year at Mar. 31, 2017		¥ 5,826,149	¥ 918,894	¥ 1,521,163		¥ (4,849)		¥ 510,700
Issuance of new shares of common stock due to exercise of stock acquisition rights		546
Purchases of treasury stock						(2,431)
Balance at beginning of fiscal year, adjusted at Mar. 31, 2017			918,894	1,521,163				510,700
Performance-based stock compensation program		(326)
Disposal of treasury stock						1,283
Net income attributable to MHFG shareholders	¥ 577,608		577,608
Change during year	222,538			220,731
Other		14
Transactions between the MHFG Group and the noncontrolling interest shareholders								106,740
Dividends paid to noncontrolling interests								(8,054)
Dividends declared			(190,361)
Net income attributable to noncontrolling interests	(24,086)							24,086
Other								1,807
Balance at end of fiscal year at Mar. 31, 2018	9,503,700	5,826,383	1,306,141	1,741,894		(5,997)	¥ 8,868,421	635,279
Cumulative effect of change in accounting principles at Mar. 31, 2018			1,540,317	(1,535,142)	[1]			(616)
Issuance of new shares of common stock due to exercise of stock acquisition rights		438
Purchases of treasury stock						(3,002)
Balance at beginning of fiscal year, adjusted at Mar. 31, 2018			2,846,458	206,752				634,663
Performance-based stock compensation program		(282)
Disposal of treasury stock						1,295
Net income attributable to MHFG shareholders	84,471		84,471
Change during year	(42,945)			(42,731)
Other		3,118
Transactions between the MHFG Group and the noncontrolling interest shareholders								166,145
Dividends paid to noncontrolling interests								(16,874)
Dividends declared			(190,384)
Net income attributable to noncontrolling interests	8,746							(8,746)
Other								(214)
Balance at end of fiscal year at Mar. 31, 2019	9,501,493	5,829,657	2,740,545	164,021		(7,704)	8,726,519	774,974
Cumulative effect of change in accounting principles at Mar. 31, 2019			1,052	(1,052)	[1]
Purchases of treasury stock						(1,908)
Balance at beginning of fiscal year, adjusted at Mar. 31, 2019			2,741,597	162,969				774,974
Performance-based stock compensation program		(178)
Disposal of treasury stock						3,197
Net income attributable to MHFG shareholders	150,195		150,195
Change during year	(172,055)			(172,463)
Other		(1,979)	(612)
Transactions between the MHFG Group and the noncontrolling interest shareholders								(52,521)
Dividends paid to noncontrolling interests								(15,722)
Dividends declared			(190,406)
Net income attributable to noncontrolling interests	43,880							(43,880)
Other								408
Balance at end of fiscal year at Mar. 31, 2020	¥ 9,175,624	¥ 5,827,500	¥ 2,700,774	¥ (9,494)		¥ (6,415)	¥ 8,512,365	¥ 663,259
[1]	See Note 2 “Issued accounting pronouncements” for further details of the cumulative-effect adjustment for AOCI.

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income		¥ 106,315	¥ 75,725	¥ 601,694
Less: Net income (loss) attributable to noncontrolling interests		(43,880)	(8,746)	24,086
Net income attributable to MHFG shareholders		150,195	84,471	577,608
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization		243,724	355,164	179,158
Provision (credit) for loan losses		156,200	32,459	(126,362)
Investment losses (gains)—net		526,359	159,789	(297,157)
Equity in losses (earnings) of equity method investees—net	[1]	(34,012)	(29,172)	(24,342)
Foreign exchange losses (gains)—net		(139,900)	155,104	(251,613)
Deferred income tax expense (benefit)		(101,941)	(157,231)	60,011
Net change in trading account assets		(7,460,802)	2,776,764	992,084
Net change in trading account liabilities		2,599,090	(2,979,299)	(518,339)
Net change in loans held for sale		(60,189)	26,659	(54,530)
Net change in accrued income		14,060	(44,519)	(31,842)
Net change in accrued expenses		(24,345)	45,653	16,517
Other—net		90,489	235,177	(682,269)
Net cash used in operating activities		(4,041,072)	661,019	(161,076)
Cash flows from investing activities:
Proceeds from sales of Available-for-sale securities	[2]	21,153,866	21,132,162	32,908,551
Proceeds from sales of Equity securities	[3]	3,123,341	3,973,437
Proceeds from maturities of Available-for-sale securities	[2]	15,350,105	15,673,340	13,819,828
Proceeds from maturities of Held-to-maturity securities		731,686	939,397	1,261,607
Purchases of Available-for-sale securities	[2]	(37,445,206)	(34,327,798)	(49,722,644)
Purchases of Held-to-maturity securities			(2,042)	(2,982)
Purchases of Equity securities	[3]	(2,900,020)	(3,429,923)
Proceeds from sales of loans		1,729,513	1,184,160	296,260
Net change in loans		(7,512,885)	(3,852,757)	(1,971,210)
Net change in call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		(5,812,860)	(2,971,007)	54,786
Proceeds from sales of premises and equipment		16,825	7,812	22,302
Purchases of premises and equipment		(243,022)	(157,714)	(292,201)
Proceeds from sales of investments in subsidiaries (affecting the scope of consolidation)		1,068	220	948
Cash outflow from deconsolidation of a subsidiary			(4,943,059)
Net cash provided by (used in) investing activities		(11,807,589)	(6,773,772)	(3,624,755)
Cash flows from financing activities:
Net change in deposits		7,920,701	3,065,826	6,083,800
Net change in call money and funds purchased, and payables under repurchase agreements and securities lending transactions		2,754,646	1,703,606	(67,508)
Net change in due to trust accounts		(62,610)	(59,373)	(130,544)
Net change in other short-term borrowings		2,936,677	270,560	257,774
Proceeds from issuance of long-term debt		2,303,803	1,659,412	1,956,007
Repayment of long-term debt		(3,273,353)	(3,241,799)	(3,310,804)
Proceeds from noncontrolling interests		131,795	219,187	76,894
Payments to noncontrolling interests		(148,673)	(579)	(12,949)
Proceeds from issuance of common stock			3	3
Proceeds from sales of treasury stock		1,517	953	1
Purchases of treasury stock		(1,441)	(2,124)	(1,611)
Dividends paid		(190,386)	(190,413)	(190,382)
Dividends paid to noncontrolling interests		(15,722)	(16,874)	(8,054)
Net cash provided by financing activities		12,356,954	3,408,385	4,652,627
Effect of exchange rate changes on cash and cash equivalents		(229,918)	206,186	(282,846)
Net increase (decrease) in cash and cash equivalents		(3,721,625)	(2,498,182)	583,950
Cash and cash equivalents at beginning of period		45,672,739	48,170,921	47,586,971
Cash and cash equivalents at end of period		41,951,114	45,672,739	48,170,921
Supplemental disclosure of cash flow information:
Interest paid		1,321,358	1,268,412	818,593
Income taxes paid		97,630	175,615	172,891
Noncash investing activities:
Transfer of loans into loans held-for-sale		¥ 29,953	2,728	¥ 35,166
Deconsolidation of Trust & Custody Services Bank, Ltd.:
Decrease in total assets			8,990,604
of which Cash and cash equivalents			4,943,059
Decrease in total liabilities			8,958,535
of which Due to trust accounts			3,620,825
Noncash assets acquired at fair value in an equity method investee	[4]		¥ 25,311
[1]	These amounts are revenues from contracts that do not meet the scope of ASC 606.
[2]	Proceeds from sales and maturities of Available-for-sale securities as well as Purchases of Available-for-sale securities include cash activity related to Other investments for the fiscal year ended March 31, 2018, the amounts of which are not significant.
[3]	Proceeds from sales of Equity securities as well as Purchases of Equity securities include cash activity related to Other investments for the fiscal years ended March 31, 2019 and 2020, the amounts of which are not significant.
[4]	Noncash assets acquired at fair value in an equity method investee was from deconsolidation of Trust & Custody Services Bank, Ltd.

Basis of presentation and summa

Basis of presentation and summary of significant accounting policies	12 Months Ended
	Mar. 31, 2020
Basis of presentation and summary of significant accounting policies	1. Basis of presentation and summary of significant accounting policies Basis of presentation Mizuho Financial Group, Inc. (“MHFG”) is a joint stock corporation with limited liability under the laws of Japan. MHFG is a holding company for Mizuho Bank, Ltd. (“MHBK”), Mizuho Trust & Banking Co., Ltd. (“MHTB”), Mizuho Securities Co., Ltd. (“MHSC”), Asset Management One Co., Ltd. (“Asset Management One”), and other subsidiaries. MHFG, through its subsidiaries (“the MHFG Group,” or “the Group”), provides domestic and international financial services in Japan and other countries. For a discussion of the Group’s segment information, see Note 31 “Business segment information.” MHFG and its domestic subsidiaries as well as its foreign subsidiaries maintain their accounting records in accordance with the accounting standards of Japan and those standards of the countries in which they are domiciled. Certain adjustments and reclassifications have been incorporated in the accompanying consolidated financial statements to conform them to the accounting principles generally accepted in the United States of America (“U.S. GAAP”). The consolidated financial statements are stated in Japanese yen, the currency of the country in which MHFG is incorporated and principally operates. The accompanying consolidated financial statements include the accounts of MHFG and its subsidiaries. MHFG’s fiscal year ends on March 31. MHFG’s subsidiaries fiscal year end is determined by each subsidiary. If the fiscal year end of a subsidiary has more than three months discrepancy from the MHFG’s fiscal year end, the subsidiary executes provisional financial closing. For those subsidiaries where the fiscal year end is not on March 31 and where the subsidiaries do not execute provisional financial close, the effect on the MHFG Group’s consolidated financial statements of all material events through the date of each of the periods presented in the consolidated financial statements has been considered for adjustment and/or disclosure. When determining whether to consolidate investee entities, the MHFG Group performs an analysis of the facts and circumstances of the particular relationships between the MHFG Group and the investee entities as well as the ownership of voting shares. The consolidated financial statements also include the accounts of VIEs for which MHFG or its subsidiaries have been determined to be the primary beneficiary in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 810, “Consolidation” (“ASC 810”). All significant intercompany transactions and balances have been eliminated upon consolidation. The MHFG Group accounts for investments in entities over which it has significant influence by using the equity method of accounting. These investments are included in Other investments and the Group’s proportionate share of income or loss is included in Equity in earnings (losses) of equity method investees—net. Certain comparative amounts for the prior period have been reclassified in order to conform to the current period’s presentation. Use of estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect reported amounts and related disclosures. Specific areas, among others, requiring the application of management’s estimates and judgment include assumptions pertaining to the allowance for loan losses, allowance for losses on off-balance-sheet . Definition of cash and cash equivalents For purposes of the consolidated statements of cash flows, Cash and cash equivalents consists of Cash and due from banks and Interest-bearing deposits in other banks. Cash deposited with central banks that must be maintained to meet minimum regulatory requirements is classified as restricted cash and included in Cash and cash equivalents. See Note 8 “Pledged assets and collateral” for more information on restricted cash. Translation of foreign currency financial statements and foreign currency transactions Financial statements of overseas entities are prepared using the functional currency of each entity and translated into Japanese yen for consolidation purposes. Assets and liabilities are translated using the fiscal-year-end Foreign currency translation gains and losses related to the financial statements of overseas entities of the MHFG Group, net of related income tax effects, are credited or charged directly to Foreign currency translation adjustments, a component of Accumulated other comprehensive income (loss), net of tax (“AOCI”). The tax effects of gains and losses related to the foreign currency translation of financial statements of overseas entities are not recognized unless it is apparent that the temporary differences will reverse in the foreseeable future. Assets and liabilities of domestic and overseas entities denominated in foreign currencies are remeasured into the functional currency of the respective entity at the fiscal year-end Call loans and call money Call loans and call money represent lending/borrowing, primarily through the Japanese short-term money market, to/from other financial institutions such as banks, insurance companies, and securities brokerage houses. Repurchase and resale agreements, securities lending and borrowing and other secured financing transactions Securities sold under agreements to repurchase (“repurchase agreements”), securities purchased under agreements to resell (“resale agreements”) and securities lending and borrowing transactions are accounted for as secured financing or lending transactions when control over the underlying securities is not deemed to be surrendered by the transferor. Otherwise, they are recorded as sales of securities with related forward repurchase commitments or purchases of securities with related forward resale commitments in accordance with ASC 860, “Transfers and Servicing” (“ASC 860”). Under resale agreements, securities borrowing and certain derivatives transactions, the MHFG Group receives collateral in the form of securities. In many cases, the MHFG Group is permitted to sell or repledge the securities obtained as collateral. Disclosures in respect of such collateral are presented in Note 8 “Pledged assets and collateral.” With respect to repurchase agreements, securities lending, and certain derivative transactions, counterparties may have the right to sell or repledge securities that the MHFG Group has pledged as collateral. The MHFG Group separately discloses these pledged securities in the consolidated balance sheets. The MHFG Group monitors credit exposure arising from resale agreements, repurchase agreements, securities borrowing and securities lending transactions on a regular basis, and additional collateral is obtained from or returned to counterparties, as appropriate. Trading securities and trading securities sold, not yet purchased Trading securities consist of securities and money market instruments that are bought and held principally for the purpose of reselling in the near term with the objective of generating profits on short-term fluctuations in price. Trading securities sold, not yet purchased, are securities and money market instruments sold to third parties that the MHFG Group does not own and is obligated to purchase at a later date to cover the short position. Trading securities and trading securities sold, not yet purchased, are recorded on the trade date. Trading securities and trading securities sold, not yet purchased, are recorded at fair value in the consolidated balance sheets in Trading account assets and Trading account liabilities with realized and unrealized gains and losses recorded on a trade date basis in Trading account gains (losses)—net in the consolidated statements of income. Interest and dividends on trading securities, including securities sold, not yet purchased, are recorded in Interest and dividend income or Interest expense on an accrual basis. Investments Debt securities that the MHFG Group has both the positive intent and ability to hold to maturity are classified as Held-to-maturity Available-for-sale The credit component of an other-than-temporary impairment of a debt security is reported in Investment gains (losses)—net, and the noncredit component is reported in Other comprehensive income (loss). See Note 3 “Investments” for further discussion of impairment. Interest and dividends, as well as amortization of premiums and accretion of discounts, are reported in Interest and dividend income. Amortization of premiums and accretion of discounts on debt securities are recognized over their remaining maturities under the interest method. Gains and losses on disposition of investments are computed using the first-in first-out Other investments include marketable and non-marketable non-marketable Derivative financial instruments Derivative financial instruments are bought and held principally for the purpose of market making for customers, proprietary trading in order to generate trading revenues and fee income, and also to manage the MHFG Group’s exposure to interest rate, credit and market risks related to asset and liability management. Such derivative financial instruments include interest rate, foreign currency, equity, commodity and credit default swap agreements, options, caps and floors, and financial futures and forward contracts. Derivatives bought and held for trading purposes are recorded in the consolidated balance sheets at fair value in Trading account assets and Trading account liabilities. The fair values of derivatives in a gain position and a loss position are reported as Trading account assets and Trading account liabilities, respectively. Derivatives used for asset and liability management include contracts that qualify for hedge accounting under ASC 815, “Derivatives and Hedging” (“ASC 815”). To be eligible for hedge accounting, derivative instruments must be highly effective in achieving offsetting changes in fair values or variable cash flows of the hedged items attributable to the particular risk being hedged. All qualifying hedging derivatives are valued at fair value and included in Trading account assets or Trading account liabilities. Derivatives that do not qualify for hedge accounting under ASC 815 are treated as trading positions and are accounted for as such. The fair value amounts recognized for all derivatives are presented on a gross basis and not offset against the amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral under the master netting agreement with the same counterparty. The fair values of derivative financial instruments are determined based on quoted market prices or broker-dealer quotes, if available. If not available, the fair values are estimated using quoted market prices for similar instruments, option or binomial pricing models or a present value cash flow analysis, utilizing current observable market information, where available. In determining the fair values, the Group considers various factors such as exchange or over-the-counter Changes in the fair values of all derivatives are recorded in earnings, except for derivatives qualifying as net investment hedges under ASC 815 which are recorded in AOCI. The changes in the fair values of all derivatives relating to foreign currency exchange rates are included in Foreign exchange gains (losses)—net and Trading account gains (losses)—net. Other elements of the changes in the fair values, including interest rate, equity and credit related components, except these of certain credit derivatives hedging the credit risk in the corporate loan portfolio, are recognized in Trading account gains (losses)—net. The net gain (loss) resulting from changes in the fair values of certain credit derivatives where the Group purchases protection to mitigate its credit risk exposure related to its corporate loan portfolio is recorded in Other noninterest income (expenses). Certain financial and hybrid instruments often contain embedded derivative instruments that possess implicit or explicit contract terms similar to those of a derivative instrument. Such derivative instruments are required to be fair-valued separately from the host contracts if they meet the bifurcation criteria of an embedded derivative. Such criteria include that the entire instrument is not marked to market through earnings, the economic characteristics and risks of the embedded contract terms are not clearly and closely related to those of the host contract and the embedded contract terms would meet the definition of a derivative on a stand-alone basis. Loans Loans are generally carried at the principal amount adjusted for unearned income and deferred net nonrefundable loan fees and costs. Loan origination fees, net of certain direct origination costs, are deferred and recognized over the contractual life of the loan as an adjustment of yield using a method that approximates the interest method. Interest income on performing loans is accrued and credited to income as it is earned. Unearned income and discounts or premiums on purchased loans are deferred and recognized over the life of the loan using a method that approximates the interest method. Loans are considered impaired when, based on current information and events, it is probable that the MHFG Group will be unable to collect all the scheduled payments of principal and interest when due according to the contractual terms of the loans. Factors considered by management in determining if a loan is impaired include delinquency status and the ability of the debtor to make payments of the principal and interest when due. Impaired loans include loans past due for 90 days or more and restructured loans that meet the definition of a troubled debt restructuring (“TDR”) in accordance with ASC 310, “Receivables” (“ASC 310”). The majority of impaired loans have no contractual delinquency due to interest reductions and/or postponement of principal and interest. In March 2020 , approved accounting for certain TDRs. The temporary TDR relief is available to banks for loan modifications , All of the MHFG Group’s impaired loans are designated as nonaccrual loans and thus interest accruals and the amortization of net origination fees are suspended and capitalized interest is written off. Cash received on nonaccrual loans is accounted for as a reduction of the loan principal if the ultimate collectability of the principal amount is in doubt, otherwise, as interest income. Loans are not restored to accrual status until interest and principal payments are current and future payments are reasonably assured. Impaired loans are restored to non-impaired non-impaired Loans that have been identified for sale are classified as loans held for sale within Other assets and are accounted for at the lower of cost or fair value on an individual loan basis. If management decides to retain certain loans held for sale for the foreseeable future or until maturity or payoff, such items are transferred to Loans at the lower of cost or fair value. Allowance and provision (credit) for loan losses The MHFG Group maintains an appropriate allowance for loan losses to absorb probable losses inherent in the loan portfolio and makes adjustments to such allowance through Provision (credit) for loan losses in the consolidated statements of income. Loan principal that management judges to be uncollectible, based on detailed loan reviews and a credit quality assessment, is charged off against the allowance for loan losses. In general, the MHFG Group charges off loans when the Group determines that the obligor should be classified as substantially bankrupt or bankrupt. See Note 4 “Loans” for the definitions of obligor categories. Obligors in the retail portfolio segment are generally determined to be substantially bankrupt when they are past due for more than six months, and as for obligors in the corporate and other portfolio segments, the Group separately monitors the credit quality of each obligor without using time-based triggers. Subsequent recoveries of previously charged-off For the corporate portfolio segment, the credit quality review process and the credit rating process serve as the basis for determining the allowance for loan losses. Through such processes loans are categorized into groups to reflect the probability of default, whereby the MHFG Group’s management assesses the ability of borrowers to service their debt, taking into consideration current financial information, ability to generate cash, historical payment experience, analysis of relevant industry segments and current trends. For the retail portfolio segment, the different categories of past due status of loans are primarily utilized in the credit quality review and the credit rating processes as the basis for determining the allowance for loan losses. The other portfolio segment consists of loans of subsidiaries other than MHBK and MHTB, such as consolidated VIEs and overseas subsidiaries. MHFG Group’s accounting policies and the methodology used to estimate the allowance for loan losses for the other portfolio segment are equivalent to the policies and methodology used for the corporate portfolio segment. The allowance for loan losses is determined in accordance with ASC 310 and ASC 450, “Contingencies” (“ASC 450”). The MHFG Group measures the impairment of a loan when it is probable that the Group will be unable to collect all amounts due according to the contractual terms of the loan agreement, based on (1) the present value of expected future cash flows, after considering the restructuring effect and subsequent payment default with respect to TDRs, discounted at the loan’s initial effective interest rate, or (2) the loan’s observable market price, or (3) the fair value of the collateral if the loan is collateral dependent. The collateral that the Group obtains for loans consists primarily of real estate. In obtaining the collateral, the Group evaluates the fair value of the collateral and its legal enforceability. The Group also performs subsequent re-evaluations The formula allowance is applied to groups of loans that are collectively evaluated for impairment. The evaluation of the inherent loss in respect of these loans involves a high degree of uncertainty, subjectivity and judgment because probable loan losses are not easily identifiable or measurable. In determining the formula allowance, the MHFG Group therefore relies on a statistical analysis that incorporates loss rates based on its own historical loss experience and third-party data such as the number of corporate default cases which is updated once a year. In determining the allowance amount, the Group analyzes (1) the probability of default: (a) by using the most recently available data from April 2008 for the corporate portfolio segment, and the most recently available data for the past six years for the retail portfolio segment, in the case of normal obligors; and (b) by using the most recently available data from April 2002 for the corporate and retail portfolio segments, in the case of watch obligors; and (2) the loss given default by using the most recently available data for the past six years for the corporate and retail portfolio segments. As it pertains to TDR loans in the retail portfolio segment, which are subject to collective evaluation for impairment, the restructuring itself, as well as subsequent payment defaults, if any, are considered in determining obligor categories. The historical loss rate is adjusted, where appropriate, to reflect current factors, such as general economic and business conditions affecting the key lending areas of the MHFG Group, credit quality trends, specific industry conditions by portfolio segments, and recent loss experience in particular segments of the portfolio. When determining the length of the period to calculate the probability of default, the Group considers the uncertainty in the economic and business conditions. The estimation of the formula allowance is analyzed on a periodic basis by comparing the allowance with the actual results subsequent to the balance sheet date. Additionally, the allowance for loan losses is adjusted, where appropriate, to reflect significant uncertain economic and business conditions, such as COVID-19 pandemic. For March 31, 2020, the Group has incorporated the estimated impact of COVID-19 pandemic by adjusting its ASC 450 collective allowance; specifically by identifying impacted industries and obligors and adjusted its historical loss formula-based allowance for these loan groups, using assumptions such as anticipated business recovery period and current forecast for the growth rate of gross domestic product. Allowance and provision (credit) for losses on off-balance-sheet The MHFG Group maintains an allowance for losses on off-balance-sheet off-balance-sheet off-balance-sheet Premises and equipment Premises and equipment are stated at historical cost, and depreciation and amortization are recorded over the estimated useful lives of the assets, except for leasehold improvements, which are amortized over the shorter of the estimated useful lives of the assets or the lease term. Depreciation and amortization are principally computed in accordance with the straight-line method with respect to buildings and leasehold improvements and in accordance with the declining-balance method with respect to other premises and equipment. The useful lives of premises and equipment are as follows: Years Buildings 3 to 50 Equipment and furniture 2 to 20 Regular repairs and maintenance costs that do not extend the estimated useful life of an asset are charged to expense as incurred. Upon sale or disposition of premises and equipment, the cost and related accumulated depreciation or amortization are removed from disposal Impairment of long-lived assets The MHFG Group’s long-lived assets that are held for use are reviewed periodically for events or changes in circumstances that indicate possible impairment. The Group’s impairment review is based on an undiscounted cash flow analysis of a group of assets, combined with associated liabilities, at the lowest level for which identifiable cash flows exist. Impairment occurs when the carrying value of the asset group exceeds the future undiscounted cash flows that the asset group is expected to generate. When impairment is identified, the future cash flows are then discounted to determine the estimated fair value of the asset group and an impairment charge is recorded for the difference between the carrying value and the estimated fair value of the asset group. The long-lived assets to be disposed of by sale are carried at the lower of the carrying amount or fair value, less estimated cost to sell. Software Internal and external costs incurred in connection with developing and obtaining software for internal use during the application development stage are capitalized. Such costs include salaries and benefits for employees directly involved with and who devote time to the project, to the extent such time is incurred directly on the internal use software project. The capitalization of software ceases when the software project has been substantially completed. The capitalized software is amortized on a straight-line basis over the estimated useful life, generally 5 to 10 years. Internal use software is reviewed for impairment whenever events or changes in circumstances indicate that its carrying amount may not be recoverable. Goodwill Goodwill represents the excess of the total fair value of the acquired company, which consists of the consideration transferred, the fair value of any interest in the acquiree already held by the acquirer and the fair value of any noncontrolling interest in the acquiree over the fair value of net identifiable assets acquired at the date of acquisition in a business combination. The MHFG Group accounts for goodwill in accordance with ASC 350, “Intangibles—Goodwill and Other” (“ASC 350”). Goodwill is recorded at a designated reporting unit level for the purpose of assessing impairment. Goodwill is not amortized but is tested for impairment at least annually or more often if events or circumstances indicate there may be impairment. For both the annual and interim tests, the Group has the option to either (a) perform a quantitative impairment test or (b) first perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, in which case the Group would perform the quantitative test. An impairment loss is recorded to the extent the carrying amount of goodwill exceeds its estimated fair value. The estimated fair value of the reporting units is derived based on valuation techniques that the Group believes market participants would use for each of the reporting units. The Group generally determines the estimated fair value by utilizing a discounted cash flow methodology or methodologies that incorporate price-to-book Intangible assets Intangible assets having definite useful lives are amortized over their estimated useful lives on either a straight-line basis or the method that reflects the pattern in which the economic benefits of the intangible assets are consumed. Intangible assets acquired in connection with the merger of MHSC and Shinko Securities Co., Ltd. (“Shinko”) and the integration of asset management functions of DIAM Co., Ltd. (“DIAM”), MHTB, Mizuho Asset Management Co., Ltd. (“MHAM”) and Shinko Asset Management Co., Ltd. (“Shinko Asset Management”) consist primarily of customer relationship intangibles, and are amortized over weighted-average amortization periods of 16 years and 16.9 years, respectively. Intangible assets having indefinite useful lives are not amortized and are subject to impairment tests. An impairment loss is recorded to the extent that the carrying amount of the indefinite-lived intangible asset exceeds its estimated fair value. For intangible assets subject to amortization, an impairment loss is recorded if the carrying amount is not recoverable and exceeds its estimated fair value. Leases The MHFG Group, as a lessee, recognizes liabilities to make lease payments and right-of-use non-lease Pension and other employee benefits MHFG and certain subsidiaries sponsor pension plans which provide defined benefits to retired employees and other postretirement benefit plans, including severance indemnities. Severance indemnities are amounts payable to eligible employees upon termination of employment and are payable as a Stock-based compensation MHFG, MHBK, MHTB and MHSC have a position-based stock compensation program for Directors (“Stock Compensation I”) and a performance-based stock compensation program for Directors (“Stock Compensation II”). For both programs, the stock-based compensation cost is determined based on the fair value of MHFG’s common stock as of grant date. For Stock Compensation I and II, the liability related to the cash-based compensation cost is remeasured at each reporting date based on the fair value of MHFG’s common stock. For Stock Compensation II, the stock-based compensation costs are recognized evenly over the graded-vesting period, which is three years. For Stock Compensation I, as the program is effectively vested on the grant date, the stock-based compensation cost is recognized on the grant date. See Note 21 “Stock-based compensation” for further details of the stock options and the stock compensation programs. Long-term debt Premiums, discounts and issuance costs of long-term debt are amortized based on a method that approximates the interest method over the respective terms of the long-term debt. Obligations under guarantees The MHFG Group provides customers with a variety of guarantees and similar arrangements, including standby letters of credit, financial and performance guarantees, credit protection, and liquidity facilities. The MHFG Group recognizes guarantee fee income over the guarantee period. The MHFG Group receives such a guarantee fee at the inception of the guarantee or in installments and, in either case, the present value of the total fees approximates the fair value of the guarantee. Fair Value Measurements The MHFG Group carries certain of its financial assets and liabilities at fair value on a recurring basis. These financial assets and liabilities are primarily composed of trading account assets, trading account liabilities and available-for-sale non-recurring Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. In accordance with ASC 820, “Fair Value Measurement” (“ASC 820”), the Group classifies its financial assets and liabilities into the fair value hierarchy (Level 1, 2, and 3). See Note 27 “Fair value” for the detailed definition of each level. When determining fair value, the MHFG Group considers the principal or most advantageous market in which the Group would transact and considers assumptions that market participants would use when pricing the asset or liability. The Group maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. See Note 27 “Fair value” for descriptions of valuation methodologies used for its assets and liabilities by product. Fee and commission income The MHFG Group recognizes revenue from contracts with customers in an amount that reflects the consideration to which the Group expects to be entitled in exchange for transferring control of a promised service. The timing of revenue recognition is dependent on whether the Group satisfies a performance obligation by transferring control of the service to a customer over time or at a point in time. Fee and commission income is presented exclusive of consumption taxes. The major components of fee and commission income are as follows. Securities-related business fees mainly consist of brokerage fees and commissions, and asset-based revenues. Brokerage fees and commissions mainly include fees earned from the execution of customer transactions and sales commissions of investment trusts. Brokerage fees and commissions are recognized at the point in time on transaction date. Asset-based revenues mainly include fees received from investment trust management companies in return for administration services, such as record keeping services, of investment trusts. The amounts of asset-based revenues are calculated based on customer’s net asset value and recognized over time in the period when the related service is provided. Deposit-related fees include service charges on consumer and commercial deposit accounts such as account transfer charges. Deposit-related fees are recognized at the point in time when the transactions occur or the related service is provided. Lending-related fees include fees for lending business such as commitment fees and arrangement fees. Remittance business fees include service charges for domestic and international funds transfers and collections. These fees are recognized at the point in time when the related service is provided. Asset management business fees consist of investment trust management fees and investment advisory fees for investment trusts. These fees are received from investment trusts in return for asset management services and/or investment advisory services on behalf of customers. The amounts of these fees are calculated based on a percentage of customer’s net asset value. These fees are recognized over time in the period when the management and/or advisory service is provided and the amount is fixed. Trust related business fees consist of trust fees earned primarily through fiduciary asset management and administrative service and other trust-related fees. Fees for fiduciary asset management and administration services for corporate pension plans and investment funds are recognized over time in the period when the related service is provided. Other trust-related fees mainly include brokerage commissions of real estate property, sales commissions of beneficial interest in real estate trust and charges for stock transfer agent services. These fees are mainly earned on a transaction basis and recognized at the point in time when the related service is provided. Agency business fees mainly include administration service fees related to the MHFG Group’s agency business such as Japan’s principal public lottery program and revenues from standing proxy services. These fees

Issued accounting pronouncement

Issued accounting pronouncements	12 Months Ended
	Mar. 31, 2020
Issued accounting pronouncements	2. Issued accounting pronouncements Adopted accounting pronouncements In January 2016, the FASB issued ASU No.2016-01, 825-10)— No.2016-01”). No.2016-01, Available-for-sale non-marketable No.2016-01, No.2016-01, (loss) (loss) In February 2016, the FASB issued ASU No.2016-02, No.2016-02”). No.2016-02 In January 2017, the FASB issued ASU No.2017-04, “Intangibles—Goodwill and Other (Topic 350)—Simplifying the Test for Goodwill Impairment” (“ASU No.2017-04”). The ASU eliminates Step 2, under which an entity had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, from the goodwill impairment test. Instead, under the ASU, an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. The MHFG Group early adopted ASU No.2017-04 in the second half of the fiscal year ended March 31, 2020. The adoption of ASU No.2017-04 did not have a material impact on the results of the Group’s goodwill impairment test. In August 2017, the FASB issued ASU No.2017-12, No.2017-12”). No.2017-12 No.2017-12 In February 2018, the FASB issued ASU No.2018-02, No.2018-02”). No.2018-02 No.2018-02 In October 2018, the FASB issued ASU No.2018-16, No.2018-16”). swap rate, the OIS rate based on the Federal Funds Effective Rate, and the Securities Industry and Financial Markets Association (“SIFMA”) Municipal Swap Rate. The MHFG Group adopted ASU No.2018-16 No.2018-16 In March 2020, the FASB issued ASU No.2020-04, No.2020-04”). Accounting pronouncements issued but not yet effective as of March 31, 2020 In June 2016, the FASB issued ASU No.2016-13, No.2016-13”). available-for-sale No.2019-04, No.2019-04”). No.2019-05, No.2019-05”). No.2019-11, No.2019-11”). No.2016-13, No.2016-13, 2019-04, 2019-05, 2019-11 R , the In August 2018, the FASB issued ASU No.2018-13, No.2018-13”). quantitative information of significant unobservable inputs used to develop Level 3 fair value measurements. The MHFG Group adopted ASU No.2018-13 In August 2018, the FASB issued ASU No.2018-14, 715-20)—Disclosure No.2018-14”). No.2018-14 e d No.2018-14 In October 2018, the FASB issued ASU No.2018-17, No.2018-17”). No.2018-17 No.2018-17

Investments

Investments	12 Months Ended
	Mar. 31, 2020
Investments	3. Investments Available-for-sale held-to-maturity The amortized cost, gross unrealized gains and losses, and fair value of available-for-sale held-to-maturity Amortized cost Gross unrealized gains Gross unrealized losses Fair value (in millions of yen) 2019 Available-for-sale Debt securities: Japanese government bonds 11,888,510 11,259 2,998 11,896,771 Japanese local government bonds 208,308 1,671 87 209,892 U.S. Treasury bonds and federal agency securities 1,008,903 644 231 1,009,316 Other foreign government bonds 1,341,564 758 455 1,341,867 Agency mortgage-backed securities (1) 530,540 14,524 593 544,471 Residential mortgage-backed securities 99,904 1,420 191 101,133 Commercial mortgage-backed securities 495,313 4,914 104 500,123 Japanese corporate bonds and other debt securities 1,743,309 7,686 1,561 1,749,434 Foreign corporate bonds and other debt securities (2) 778,088 3,047 226 780,909 Total 18,094,439 45,923 6,446 18,133,916 Held-to-maturity Debt securities: Japanese government bonds 1,119,899 19,907 — 1,139,806 Agency mortgage-backed securities (3) 484,205 — 14,423 469,782 Total 1,604,104 19,907 14,423 1,609,588 Amortized cost Gross unrealized gains Gross unrealized losses Fair value (in millions of yen) 2020 Available-for-sale Debt securities: Japanese government bonds 12,651,677 1,319 50,224 12,602,772 Japanese local government bonds 272,412 649 494 272,567 U.S. Treasury bonds and federal agency securities 927,172 7,733 — 934,905 Other foreign government bonds 1,408,009 3,273 202 1,411,080 Agency mortgage-backed securities (1) 494,958 10,490 434 505,014 Residential mortgage-backed securities 83,077 1,405 151 84,331 Commercial mortgage-backed securities 609,559 5,551 106 615,004 Japanese corporate bonds and other debt securities 1,836,540 7,489 8,772 1,835,257 Foreign corporate bonds and other debt securities (2) 849,595 2,595 168 852,022 Total 19,132,999 40,504 60,551 19,112,952 Held-to-maturity Debt securities: Japanese government bonds 479,936 13,357 — 493,293 Agency mortgage-backed securities (3) 382,095 1,245 1,303 382,037 Total 862,031 14,602 1,303 875,330 Notes: (1) Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥517,330 million and ¥27,141 million, respectively, at March 31, 2019, and ¥504,953 million and ¥61 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government. (2) Other debt securities presented in this line primarily consist of Foreign negotiable certificates of deposit (“NCDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥246,503 million at March 31, 2019, and ¥271,387 million at March 31, 2020. (3) All Agency mortgage-backed securities presented in this line are Ginnie Mae securities. Contractual maturities The amortized cost and fair value of available-for-sale held-to-maturity Amortized cost Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 5,872,058 4,980,539 1,753,300 45,780 12,651,677 Japanese local government bonds 11,530 171,825 84,528 4,529 272,412 U.S. Treasury bonds and federal agency securities 883,432 43,740 — — 927,172 Other foreign government bonds 1,029,641 378,368 — — 1,408,009 Agency mortgage-backed securities — — — 494,958 494,958 Residential mortgage-backed securities — — — 83,077 83,077 Commercial mortgage-backed securities 16,372 202,044 390,343 800 609,559 Japanese corporate bonds and other debt securities 98,532 868,704 545,320 323,984 1,836,540 Foreign corporate bonds and other debt securities 377,642 327,312 141,755 2,886 849,595 Total 8,289,207 6,972,532 2,915,246 956,014 19,132,999 Held-to-maturity Debt securities: Japanese government bonds — 479,936 — — 479,936 Agency mortgage-backed securities — — — 382,095 382,095 Total — 479,936 — 382,095 862,031 Fair value Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 5,872,485 4,963,282 1,722,090 44,915 12,602,772 Japanese local government bonds 11,537 172,052 84,443 4,535 272,567 U.S. Treasury bonds and federal agency securities 890,367 44,538 — — 934,905 Other foreign government bonds 1,031,189 379,891 — — 1,411,080 Agency mortgage-backed securities — — — 505,014 505,014 Residential mortgage-backed securities — — — 84,331 84,331 Commercial mortgage-backed securities 16,396 203,233 394,561 814 615,004 Japanese corporate bonds and other debt securities 98,589 868,675 544,559 323,434 1,835,257 Foreign corporate bonds and other debt securities 378,464 328,918 141,754 2,886 852,022 Total 8,299,027 6,960,589 2,887,407 965,929 19,112,952 Held-to-maturity Debt securities: Japanese government bonds — 493,293 — — 493,293 Agency mortgage-backed securities — — — 382,037 382,037 Total — 493,293 — 382,037 875,330 Other-than-temporary impairment The MHFG Group performs periodic reviews to identify impaired securities in accordance with ASC 320, “Investments—Debt Securities” (“ASC 320”). For debt securities, in the cases where the MHFG Group has the intent to sell a debt security or more likely than not will be required to sell a debt security before the recovery of its amortized cost basis, the full amount of an other-than-temporary impairment loss is recognized immediately through earnings. In other cases, the MHFG Group evaluates expected cash flows to be received and determines if a credit loss exists, and if so, the amount of an other-than-temporary impairment related to the credit loss is recognized in earnings, while the remaining decline in fair value is recognized in other comprehensive income, net of applicable taxes. Effective April 1, 2018, the available-for-sale No.2016-01, The other-than-temporary impairment losses on available-for-sale s held-to-maturity Continuous unrealized loss position The following table shows the gross unrealized losses and fair value of available-for-sale held-to-maturity Less than 12 months 12 months or more Total Fair value Gross unrealized losses Fair value Gross unrealized losses Fair value Gross unrealized losses (in millions of yen) 2019 Available-for-sale Debt securities: Japanese government bonds 2,296,536 1,441 1,332,688 1,557 3,629,224 2,998 Japanese local government bonds 9,752 32 38,873 55 48,625 87 U.S. Treasury bonds and federal agency securities 506,176 231 — — 506,176 231 Other foreign government bonds 438,771 321 26,782 134 465,553 455 Agency mortgage-backed securities (1) 466 2 37,706 591 38,172 593 Residential mortgage-backed securities — — 16,729 191 16,729 191 Commercial mortgage-backed securities 11,256 44 36,760 60 48,016 104 Japanese corporate bonds and other debt securities 417,825 924 440,937 637 858,762 1,561 Foreign corporate bonds and other debt securities 129,164 142 79,716 84 208,880 226 Total 3,809,946 3,137 2,010,191 3,309 5,820,137 6,446 Held-to-maturity Debt securities: Agency mortgage-backed securities (2) — — 469,782 14,423 469,782 14,423 Total — — 469,782 14,423 469,782 14,423 2020 Available-for-sale Debt securities: Japanese government bonds 10,339,320 43,204 283,561 7,020 10,622,881 50,224 Japanese local government bonds 162,665 418 34,114 76 196,779 494 U.S. Treasury bonds and federal agency securities — — — — — — Other foreign government bonds 196,990 202 — — 196,990 202 Agency mortgage-backed securities (1) 30,913 227 9,504 207 40,417 434 Residential mortgage-backed securities 9,524 62 5,450 89 14,974 151 Commercial mortgage-backed securities 15,115 85 7,478 21 22,593 106 Japanese corporate bonds and other debt securities 669,572 5,507 608,361 3,265 1,277,933 8,772 Foreign corporate bonds and other debt securities 152,058 165 5,564 3 157,622 168 Total 11,576,157 49,870 954,032 10,681 12,530,189 60,551 Held-to-maturity Debt securities: Agency mortgage-backed securities (2) — — 191,244 1,303 191,244 1,303 Total — — 191,244 1,303 191,244 1,303 Notes: (1) Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥11,107 million and ¥27,065 million, respectively, at March 31, 2019, and ¥40,417 million and ¥0 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government. (2) All Agency mortgage-backed securities presented in this line are Ginnie Mae securities. At March 31, 2020, the MHFG Group did not intend to sell the debt securities in an unrealized loss position and it was not more likely than not that the MHFG Group would be required to sell them before the recovery of their amortized cost bases. For Japanese government bonds and Agency mortgage-backed securities, their entire amortized cost bases were expected to be recovered since the unrealized losses had not resulted from credit deterioration, but primarily from changes in interest rates. For the debt securities other than those described above, except for the securities for which credit losses have been recognized in income, the MHFG Group determined that their entire amortized cost bases were expected to be recovered, after considering various factors such as the extent to which their fair values were below their amortized cost bases, the external and/or internal ratings and the present values of cash flows expected to be collected. Based on the aforementioned evaluation, except for the securities for which credit losses have been recognized in income, the MHFG Group determined that the debt securities in an unrealized loss position were not considered other-than-temporarily impaired. Realized gains and losses The following table shows the realized gains and losses on sales of available-for-sale 2018 2019 (Note) 2020 (Note) (in millions of yen) Gross realized gains 314,948 23,777 41,903 Gross realized losses (41,044 ) (26,299 ) (13,398 ) Net realized gains (losses) on sales of available-for-sale 273,904 (2,522 ) 28,505 Note: Effective April 1, 2018, the available-for-sale Equity securities Equity securities include securities which have readily determinable fair values, securities which qualify for the practical expedient to estimate fair value using the net asset value per share (or its equivalent), and securities which are without readily determinable fair values. Equity securities which have readily determinable fair values mainly consist of common stock of Japanese listed companies. Equity securities without readily determinable fair values include non-marketable Net gains and losses The following table shows the details of the net gains and losses on Equity securities for the fiscal years ended March 31, 2019 and 2020: 2019 2020 (in millions of yen) Net gains (losses) recognized during the period on equity securities (155,947 ) (557,391 ) Less: Net gains (losses) recognized during the period on equity securities sold during the period 34,034 1,710 Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting period (189,981 ) (559,101 ) Equity securities without readily determinable fair values The following table shows carrying amounts of equity securities without readily determinable fair values, for which the measurement alternative is used, and cumulative amounts due to downward adjustments and impairments and upward adjustments, at March 31, 2019 and 2020: 2019 2020 (in millions of yen) Carrying amounts at the end of the period 212,270 419,775 Downward adjustments and impairments 1,413 2,435 Upward adjustments 2,373 9,128 The following table shows amounts recognized in earnings during the period due to downward adjustments and impairments and upward adjustments for equity securities without readily determinable fair values. 2019 2020 (in millions of yen) Downward adjustments and impairments 1,413 1,272 Upward adjustments 2,373 6,928 The MHFG Group elected to measure all equity securities without readily determinable fair values, which do not qualify for the practical expedient to estimate fair value, using the measurement alternative, which is made on an instrument-by-instrument Other investments The following table summarizes the composition of Other investments at March 31, 2019 and 2020: 2019 2020 (in millions of yen) Equity method investments 354,268 404,513 Investments held by consolidated investment companies 35,472 39,438 Total 389,740 443,951 Equity method investments Investments in investees over which the MHFG Group has the ability to exert significant influence are accounted for using the equity method of accounting. Such investments included marketable equity securities with carrying values of ¥201,034 million and ¥213,243 million, at March 31, 2019 and 2020, respectively. The aggregate market values of these marketable equity securities were ¥308,137 million and ¥287,488 million, respectively. The majority of aggregate market values of these marketable equity securities include Orient Corporation, the Chiba Kogyo Bank, Ltd. , and Mizuho ing Company, Limi t , 15.00% non-marketable and and Investments held by consolidated investment companies The MHFG Group consolidates certain investment companies over which it has control through either ownership or other means. Investment companies are subject to specialized industry accounting which requires investments to be carried at fair value, with changes in fair value recorded in earnings. The MHFG Group maintains this specialized industry accounting for investments held by consolidated investment companies, which consist of marketable and non-marketable

Loans

Loans	12 Months Ended
	Mar. 31, 2020
Loans	4. Loans The table below presents loans outstanding by domicile and industry of borrower at March 31, 2019 and 2020: 2019 2020 (in millions of yen) Domestic: Manufacturing 9,553,854 9,731,028 Construction and real estate 8,950,577 9,603,433 Services 5,016,971 5,992,511 Wholesale and retail 5,159,356 5,219,727 Transportation and communications 3,693,491 3,832,884 Banks and other financial institutions 4,345,589 4,634,442 Government and public institutions 2,358,904 2,198,805 Other industries (Note) 5,472,597 5,389,347 Individuals: Mortgage loans 8,950,216 8,567,099 Other 907,589 861,235 Total domestic 54,409,144 56,030,511 Foreign: Commercial and industrial 19,126,182 20,818,709 Banks and other financial institutions 9,086,721 10,475,277 Government and public institutions 296,872 317,284 Other 33,171 35,388 Total foreign 28,542,946 31,646,658 Total 82,952,090 87,677,169 Less: Unearned income and deferred loan fees—net 152,147 149,081 Total loans before allowance for loan losses 82,799,943 87,528,088 Note: Other industries of d Net losses on sales of loans were ¥87 million, ¥2,018 million and ¥1,036 Credit quality information In accordance with the MHFG Group’s credit risk management policies, the Group uses an internal rating system that consists of credit ratings for the corporate portfolio segment and pool allocations for the retail portfolio segment as the basis of its risk management infrastructure. Credit ratings consist of obligor ratings which represent the level of credit risk of the obligor, and transaction ratings which represent the ultimate possibility of incurring losses on individual loans by taking into consideration various factors such as collateral or guarantees involved. In principle, obligor ratings are applied to all obligors except those to which pool allocations are applied, and are subject to regular review at least once a year as well as special review which is required whenever the obligor’s credit standing changes. Pool allocations are applied to small loans that are less than a specified amount by pooling customers and loans with similar risk characteristics, and the risk is assessed mainly based on past due status and managed according to such pools. The Group generally reviews the appropriateness and effectiveness of the approach to obligor ratings and pool allocations once a year in accordance with predetermined policies and procedures. The table below presents the MHFG Group’s definition of obligor ratings used by MHBK and MHTB: Obligor category (1)(2) Obligor rating (3) Definition Normal A Obligors whose certainty of debt fulfillment is very high, hence their level of credit risk is very low. B Obligors whose certainty of debt fulfillment poses no problems for the foreseeable future, and their level of credit risk is low. C Obligors whose certainty of debt fulfillment and their level of credit risk pose no problems for the foreseeable future. D Obligors whose current certainty of debt fulfillment poses no problems, however, their resistance to future economic environmental changes is low. Watch E1 Obligors that require observation going forward because of either minor concerns regarding their financial position, or their somewhat weak or unstable business conditions. E2 Obligors that require special observation going forward because of problems with their borrowings such as reduced or suspended interest payments, problems with debt fulfillment such as failure to make principal or interest payments, or problems with their financial position as a result of their weak or unstable business conditions. Intensive control F Obligors that are not yet bankrupt but are in financial difficulties and are deemed likely to become bankrupt in the future because of insufficient progress in implementing their management improvement plans or other measures (including obligors that are receiving ongoing support from financial institutions). Substantially bankrupt G Obligors that have not yet become legally or formally bankrupt but are substantially insolvent because they are in serious financial difficulties and are deemed to be incapable of being restructured. Bankrupt H Obligors that have become legally or formally bankrupt. Notes: (1) Special attention obligors are watch obligors with debt in TDR or 90 days or more delinquent debt. Loans to such obligors are considered impaired. (2) The Group classifies loans to special attention, intensive control, substantially bankrupt and bankrupt obligors as impaired loans. (3) Equivalent obligor ratings are determined for the other portfolio segment. The table below presents credit quality information of loans based on the MHFG Group’s internal rating system at March 31, 2019 and 2020: Normal obligors Watch obligors excluding special attention obligors (1) Impaired loans Total Corporate Retail (2) Other (3) Corporate Retail (2) Other (3) (in millions of yen) 2019 Domestic: Manufacturing 9,205,542 69,080 19,805 141,202 8,278 1,303 108,644 9,553,854 Construction and real estate 8,182,062 505,142 15,920 186,753 14,490 25 46,185 8,950,577 Services 4,665,709 165,643 3,281 90,178 18,586 1 73,573 5,016,971 Wholesale and retail 4,682,630 161,392 26,881 127,695 25,553 591 134,614 5,159,356 Transportation and communications 3,543,952 71,934 934 37,993 7,472 — 31,206 3,693,491 Banks and other financial institutions 4,304,483 1,534 72 28,881 319 — 10,300 4,345,589 Government and public institutions 2,358,899 5 — — — — — 2,358,904 Other industries (4) 3,126,217 2,450 2,323,197 7,725 421 3,633 8,954 5,472,597 Individuals 233,986 9,384,955 64,974 21,127 70,427 1,168 81,168 9,857,805 Total domestic 40,303,480 10,362,135 2,455,064 641,554 145,546 6,721 494,644 54,409,144 Foreign: Commercial and industrial 16,101,326 182 2,488,800 347,060 — 38,404 150,410 19,126,182 Banks and other financial institutions 8,583,432 — 492,831 10,458 — — — 9,086,721 Government and public institutions 296,870 — — — — — 2 296,872 Other 1,480 9,713 19,690 333 — 879 1,076 33,171 Total foreign 24,983,108 9,895 3,001,321 357,851 — 39,283 151,488 28,542,946 Total 65,286,588 10,372,030 5,456,385 999,405 145,546 46,004 646,132 82,952,090 2020 Domestic: Manufacturing 9,007,095 62,921 17,445 475,983 7,474 684 159,426 9,731,028 Construction and real estate 8,849,784 473,339 12,710 201,384 10,928 — 55,288 9,603,433 Services 5,600,528 159,657 2,943 131,783 16,602 15 80,983 5,992,511 Wholesale and retail 4,766,460 145,568 17,156 119,778 22,363 873 147,529 5,219,727 Transportation and communications 3,692,025 65,535 395 44,250 7,664 303 22,712 3,832,884 Banks and other financial institutions 4,595,441 1,593 347 24,686 429 — 11,946 4,634,442 Government and public institutions 2,198,796 9 — — — — — 2,198,805 Other industries (4) 3,106,282 2,684 2,230,748 15,238 372 15,038 18,985 5,389,347 Individuals 208,832 8,989,113 63,185 20,990 60,128 2,279 83,807 9,428,334 Total domestic 42,025,243 9,900,419 2,344,929 1,034,092 125,960 19,192 580,676 56,030,511 Foreign: Commercial and industrial 17,806,263 284 2,526,317 314,273 — 36,593 134,979 20,818,709 Banks and other financial institutions 9,745,247 — 726,823 3,207 — — — 10,475,277 Government and public institutions 303,393 — 13,129 762 — — — 317,284 Other 1,333 10,406 20,558 1,684 15 843 549 35,388 Total foreign (5) 27,856,236 10,690 3,286,827 319,926 15 37,436 135,528 31,646,658 Total 69,881,479 9,911,109 5,631,756 1,354,018 125,975 56,628 716,204 87,677,169 Notes: (1) Special attention obligors are watch obligors with debt in TDR or 90 days or more delinquent debt. Loans to such obligors are considered impaired. (2) The primary component of the retail portfolio segment is mortgage loans to individuals which obligor category is classified based on past due status. The trigger to reclassify obligors from normal obligors to watch obligors excluding special attention obligors is when the past due status is more than 30 days. (3) Non-impaired (4) Other industries of domestic includes trade receivables and lease receivables of consolidated VIEs. (5) Impaired loans to foreign borrowers decreased by ¥15,960 million due mainly to the sale of certain loans, partly offset by deterioration of credit status of certain other borrowers. Impaired loans The MHFG Group considers loans to be impaired when it is probable that the Group will be unable to collect all the scheduled payments of principal and interest when due according to the contractual terms of the loans. The Group classifies loans to special attention, intensive control, substantially bankrupt and bankrupt obligors as impaired loans, and all of the Group’s impaired loans are designated as nonaccrual loans. There are no loans that are ninety days past due and still accruing. The Group does not have any loans to borrowers that cause management to have serious doubts as to the ability of such borrowers to comply with the present loan repayment terms for the periods presented other than those already designated as impaired loans. The table below presents impaired loans information at March 31, 2019 and 2020: Recorded investment (1) Unpaid principal balance Related allowance (3) Average recorded investment Interest income recognized (4) Requiring an allowance for loan losses Not requiring an allowance for loan losses (2) Total (in millions of yen) 2019 Domestic: Manufacturing 103,039 5,605 108,644 111,533 39,301 122,764 1,404 Construction and real estate 36,873 9,312 46,185 51,158 4,661 42,224 487 Services 64,021 9,552 73,573 79,736 16,311 67,679 1,058 Wholesale and retail 124,911 9,703 134,614 147,665 38,763 130,860 1,814 Transportation and communications 28,297 2,909 31,206 32,139 13,146 29,864 412 Banks and other financial institutions 6,473 3,827 10,300 10,300 1,327 10,671 109 Other industries 8,867 87 8,954 9,149 5,761 6,042 29 Individuals 37,488 43,680 81,168 88,331 2,630 86,082 1,326 Total domestic 409,969 84,675 494,644 530,011 121,900 496,186 6,639 Foreign: Total foreign (5) 119,079 32,409 151,488 164,984 47,345 113,559 1,518 Total 529,048 117,084 646,132 694,995 169,245 609,745 8,157 2020 Domestic: Manufacturing 152,865 6,561 159,426 162,742 62,879 139,123 2,292 Construction and real estate 47,413 7,875 55,288 62,064 8,366 50,343 593 Services 71,358 9,625 80,983 85,565 20,117 78,583 973 Wholesale and retail 139,338 8,191 147,529 158,933 48,582 139,042 1,845 Transportation and communications 20,203 2,509 22,712 23,555 7,318 25,549 383 Banks and other financial institutions 8,193 3,753 11,946 11,946 1,541 10,565 129 Other industries 18,709 276 18,985 20,716 8,606 14,512 194 Individuals 42,632 41,175 83,807 88,315 6,382 82,456 1,253 Total domestic 500,711 79,965 580,676 613,836 163,791 540,173 7,662 Foreign: Total foreign (5) 95,289 40,239 135,528 151,212 67,235 123,313 3,032 Total 596,000 120,204 716,204 765,048 231,026 663,486 10,694 Notes: (1) Amounts represent the outstanding balances of nonaccrual loans. The MHFG Group’s policy for placing loans in nonaccrual status corresponds to the Group’s definition of impaired loans. (2) These impaired loans do not require an allowance for loan losses because the MHFG Group has sufficient collateral to cover probable loan losses. (3) The allowance for loan losses on impaired loans includes the allowance for groups of loans which were collectively evaluated for impairment, in addition to the allowance for those loans that were individually evaluated for impairment. The total carrying amount of the groups of loans which were collectively evaluated for impairment at March 31, 2019 and 2020 was ¥257,099 million and ¥260,596 million, respectively. (4) Amounts represent the amount of interest income on impaired loans recognized on a cash basis and included in Interest income on loans in the consolidated statements of income. (5) The majority of total foreign consist of commercial and industrial loans. The remaining balance of impaired loans that have been partially charged off, was ¥25,097 million and ¥20,378 million as of March 31, 2019 and 2020, respectively. Troubled debt restructurings The MHFG Group considers a loan modification to be a TDR when, for economic or legal reasons related to the obligor’s financial difficulties, it grants a concession to the obligor that it would not otherwise consider. The Group considers the relevant obligor to be in financial difficulty generally when its obligor rating is E2 or below. The following table presents modified loans that were determined to be TDRs during the fiscal years ended March 31, 2019 and 2020: Loan forgiveness or debt to equity swaps Interest rate reduction and/or postponement of principal and/or interest Recorded investment (1) Charge-offs (in millions of yen) 2019 Domestic: Manufacturing — — 134,544 Construction and real estate — — 39,254 Services — — 87,468 Wholesale and retail — — 167,299 Transportation and communications — — 33,991 Banks and other financial institutions — — 17,286 Other industries — — 120 Individuals — — 42,330 Total domestic — — 522,292 Foreign: Total foreign (2) 984 1,964 44,033 Total 984 1,964 566,325 2020 Domestic: Manufacturing 689 3,806 148,564 Construction and real estate — — 31,803 Services — — 78,211 Wholesale and retail — 196 169,224 Transportation and communications — — 18,700 Banks and other financial institutions — — 16,962 Other industries — — 1,366 Individuals — — 14,000 Total domestic 689 4,002 478,830 Foreign: Total foreign (2) 466 4,906 114,159 Total 1,155 8,908 592,989 Notes: (1) Amounts represent the book values of loans immediately after the restructurings. (2) The majority of total foreign consist of commercial and industrial loans. Payment default is deemed to occur when the loan becomes three months past due or the obligor is downgraded to the category of substantially bankrupt or bankrupt. The following table presents payment defaults which occurred during the fiscal years ended March 31, 2019 and 2020 with respect to the loans modified as TDRs within the previous twelve months: Recorded investment 2019 2020 (in millions of yen) Domestic: Manufacturing 1,173 3,752 Construction and real estate 121 345 Services 1,335 3,822 Wholesale and retail 15,087 19,018 Transportation and communications 878 824 Banks and other financial institutions 66 66 Other industries 1,650 — Individuals 2,152 2,545 Total domestic 22,462 30,372 Foreign: Total foreign 5,418 11,442 Total 27,880 41,814 Age analysis of past due loans The table below presents an analysis of the age of the recorded investment in loans that are past due at March 31, 2019 and 2020: 30-59 past due 60-89 past due 90 days or more past due Total past due Current Total (in millions of yen) 2019 Domestic: Manufacturing 2,210 513 7,036 9,759 9,544,095 9,553,854 Construction and real estate 1,010 1,054 31,092 33,156 8,917,421 8,950,577 Services 633 196 3,494 4,323 5,012,648 5,016,971 Wholesale and retail 1,614 1,415 7,868 10,897 5,148,459 5,159,356 Transportation and communications 363 256 2,119 2,738 3,690,753 3,693,491 Banks and other financial institutions 3 484 6 493 4,345,096 4,345,589 Government and public institutions — — — — 2,358,904 2,358,904 Other industries 2 — 57 59 5,472,538 5,472,597 Individuals 27,139 11,013 28,965 67,117 9,790,688 9,857,805 Total domestic 32,974 14,931 80,637 128,542 54,280,602 54,409,144 Foreign: Total foreign (Note) 668 211 26,316 27,195 28,515,751 28,542,946 Total 33,642 15,142 106,953 155,737 82,796,353 82,952,090 2020 Domestic: Manufacturing 1,109 386 10,997 12,492 9,718,536 9,731,028 Construction and real estate 1,266 687 21,518 23,471 9,579,962 9,603,433 Services 792 548 6,714 8,054 5,984,457 5,992,511 Wholesale and retail 1,748 2,446 11,972 16,166 5,203,561 5,219,727 Transportation and communications 56 35 2,051 2,142 3,830,742 3,832,884 Banks and other financial institutions — — 109 109 4,634,333 4,634,442 Government and public institutions — — — — 2,198,805 2,198,805 Other industries 28 20 1,326 1,374 5,387,973 5,389,347 Individuals 21,376 10,876 34,793 67,045 9,361,289 9,428,334 Total domestic 26,375 14,998 89,480 130,853 55,899,658 56,030,511 Foreign: Total foreign (Note) 1,214 181 28,722 30,117 31,616,541 31,646,658 Total 27,589 15,179 118,202 160,970 87,516,199 87,677,169 Note: The majority of total foreign consist of commercial and industrial loans.

Allowance for loan losses

Allowance for loan losses	12 Months Ended
	Mar. 31, 2020
Allowance for loan losses	5. Allowance for loan losses In accordance with ASC 450, a formula-based allowance utilizing historical loss factors, after adjusting for existing economic conditions where appropriate, is applied to groups of non-homogeneous as project finance, asset finance and real estate finance. The retail portfolio segment consists mainly of residential mortgage loans, originated by MHBK. The other portfolio segment consists of loans of subsidiaries other than MHBK and MHTB, such as consolidated VIEs and overseas subsidiaries. See Note 1 “Basis of presentation and summary of significant accounting policies” for further details of the methodology used to determine the allowance for loan losses and Note 4 “Loans” for further details of obligor ratings and pool allocations. Changes in Allowance for loan losses by portfolio segment for the fiscal years ended March 31, 2018, 2019 and 2020 are shown below: Corporate Retail Other Total (in millions of yen) 2018 Balance at beginning of fiscal year 407,327 36,923 35,423 479,673 Provision (credit) for loan losses (123,470 ) (7,427 ) 4,535 (126,362 ) Charge-offs (44,621 ) (2,118 ) (9,123 ) (55,862 ) Recoveries 12,924 814 1,482 15,220 Net charge-offs (31,697 ) (1,304 ) (7,641 ) (40,642 ) Others (Note) (3,088 ) — 321 (2,767 ) Balance at end of fiscal year 249,072 28,192 32,638 309,902 2019 Balance at beginning of fiscal year 249,072 28,192 32,638 309,902 Provision (credit) for loan losses 31,693 (2,658 ) 3,424 32,459 Charge-offs (39,728 ) (2,856 ) (4,940 ) (47,524 ) Recoveries 11,019 552 2,532 14,103 Net charge-offs (28,709 ) (2,304 ) (2,408 ) (33,421 ) Others (Note) 847 — (2,586 ) (1,739 ) Balance at end of fiscal year 252,903 23,230 31,068 307,201 2020 Balance at beginning of fiscal year 252,903 23,230 31,068 307,201 Provision (credit) for loan losses 155,576 760 (136 ) 156,200 Charge-offs (33,971 ) (3,840 ) (6,547 ) (44,358 ) Recoveries 26,155 700 1,061 27,916 Net charge-offs (7,816 ) (3,140 ) (5,486 ) (16,442 ) Others (Note) (5,454 ) — (650 ) (6,104 ) Balance at end of fiscal year 395,209 20,850 24,796 440,855 Note: Others includes primarily foreign exchange translation. The table below presents Allowance for loan losses and loans outstanding by portfolio segment disaggregated on the basis of impairment method at March 31, 2019 and 2020: Corporate Retail Other Total (in millions of yen) 2019 Allowance for loan losses 252,903 23,230 31,068 307,201 of which individually evaluated for impairment 139,472 2,122 8,933 150,527 of which collectively evaluated for impairment 113,431 21,108 22,135 156,674 Loans (Note) 66,804,088 10,596,994 5,551,008 82,952,090 of which individually evaluated for impairment 539,893 20,886 54,319 615,098 of which collectively evaluated for impairment 66,264,195 10,576,108 5,496,689 82,336,992 2020 Allowance for loan losses 395,209 20,850 24,796 440,855 of which individually evaluated for impairment 231,941 1,704 5,443 239,088 of which collectively evaluated for impairment 163,268 19,146 19,353 201,767 Loans (Note) 71,840,922 10,112,617 5,723,630 87,677,169 of which individually evaluated for impairment 971,153 19,279 44,244 1,034,676 of which collectively evaluated for impairment 70,869,769 10,093,338 5,679,386 86,642,493 Note: Amounts represent loan balances before deducting unearned income and deferred loan fees.

Premises and equipment

Premises and equipment	12 Months Ended
	Mar. 31, 2020
Premises and equipment	6. Premises and equipment Premises and equipment at March 31, 2019 and 2020 consist of the following: 2019 2020 (in millions of yen) Land 563,032 557,943 Buildings 826,781 657,774 Equipment and furniture 472,186 442,302 Leasehold improvements 97,508 228,383 Construction in progress 37,174 73,164 Software 1,366,481 1,359,120 Total 3,363,162 3,318,686 Less: Accumulated depreciation and amortization 1,462,210 1,462,438 Premises and equipment—net 1,900,952 1,856,248 Depreciation and amortization expense for premises and equipment for the fiscal years ended March 31, 2018, 2019 and 2020 was ¥169,346 million, ¥345,560 million and ¥234,457 million, respectively. Depreciation and amortization expense related to s The MHFG Group recognized impairment losses of ¥27,428 million on premises and equipment for the fiscal year ended March 31, 2019, of which ¥8,910 million was recorded in General and administrative expenses and ¥18,518 million was recorded in Occupancy expenses. Such losses included ¥15,761 million of impairment losses primarily on real estate of certain branches recognized in Retail & Business Banking Company. In relation to the Group’s branch network strategy, these branches are either no longer being used for its banking operations or the carrying amounts are not recoverable because of the Group’s intention to close these branches. The MHFG Group recognized impairment losses of ¥13,490 million on premises and equipment for the fiscal year ended March 31, 2020, of which ¥6,813 million was recorded in General and administrative expenses and ¥6,677 million was recorded in Occupancy expenses. Such losses included ¥6,774 million of impairment losses related mainly to entity-wide software that are no longer to be used. In addition, ¥5,587 million of impairment losses were recognized on real estate used mainly as the entity-wide assets and certain branches in Retail & Business Banking Company. These real estates are either no longer being used or the carrying amounts are not recoverable.

Goodwill and intangible assets

Goodwill and intangible assets	12 Months Ended
	Mar. 31, 2020
Goodwill and intangible assets	7. Goodwill and intangible assets Goodwill The changes in Goodwill during the fiscal years ended March 31, 2018, 2019 and 2020 are as follows: 2018 2019 2020 (in millions of yen) Balance at beginning of fiscal year 95,176 95,184 95,151 Impairment losses recognized — — (2,155 ) Foreign exchange translation 8 (33 ) 1 Balance at end of fiscal year 95,184 95,151 92,997 Gross amount of goodwill (Note) 170,926 169,489 169,313 Accumulated impairment losses 75,742 74,338 76,316 Note: Goodwill is recorded at a designated reporting unit level for the purpose of assessing impairment. Goodwill is not allocated to the reportable segments in Note 31 “Business segment information.” Intangible assets The table below presents the gross carrying amount, accumulated amortization and net carrying amount of intangible assets, at March 31, 2019 and 2020: 2019 2020 Gross carrying amount Accumulated amortization Net carrying amount Gross carrying amount Accumulated amortization Net carrying amount (in millions of yen) Intangible assets subject to amortization: Customer relationships (Note) 126,882 61,630 65,252 126,979 70,904 56,075 Other 1,698 1,412 286 1,693 1,460 233 Total 128,580 63,042 65,538 128,672 72,364 56,308 Intangible assets not subject to amortization: Total 8,702 — 8,702 8,381 — 8,381 Total 137,282 63,042 74,240 137,053 72,364 64,689 Note: Customer relationships were acquired in connection with the merger of MHSC and Shinko on May 7, 2009 and the integration among asset management companies on October 1, 2016. See Note 1 “Basis of presentation and summary of significant accounting policies” for further information. For the fiscal years ended March 31, 2018, 2019 and 2020, the MHFG Group recognized ¥9,812 million, ¥9,604 million and ¥9,267 million, respectively, of amortization expense in respect of intangible assets, reported in Other noninterest expenses. The table below presents the estimated aggregate amortization expense in respect of intangible assets for the next five years: (in millions of yen) Fiscal year ending March 31: 2021 8,237 2022 7,702 2023 7,184 2024 6,666 2025 6,154

Pledged assets and collateral

Pledged assets and collateral	12 Months Ended
	Mar. 31, 2020
Pledged assets and collateral	8. Pledged assets and collateral The following amounts, by balance sheet classification, have been pledged as collateral for borrowings and for other purposes at March 31, 2019 and 2020: 2019 2020 (in billions of yen) Interest-bearing deposits in other banks 68 69 Trading account assets 4,137 5,705 Investments 6,076 4,155 Loans 4,055 3,887 Other assets 1,886 2,786 Total 16,222 16,602 The associated liabilities collateralized by the above assets at March 31, 2019 and 2020 are summarized below: 2019 2020 (in billions of yen) Deposits 386 1,057 Payables under repurchase agreements 3,435 5,480 Payables under securities lending transactions 1,675 1,094 Other short-term borrowings 519 4,014 Long-term debt 1,431 213 Total 7,446 11,858 The Bank of Japan (“the BOJ”) requires private depository institutions to maintain a certain amount of funds as reserves in current accounts with the BOJ, based on average deposit balances and certain other factors. There are similar reserve deposit requirements for foreign branches and subsidiaries engaged in banking businesses in foreign countries. These amounts are deemed to be restricted cash. At March 31, 2019 and 2020, the deposit amounts maintained with the BOJ and foreign central banks, which were included in Cash and due from banks and Interest-bearing deposits in other banks, were ¥43,552 billion and ¥38,808 billion, respectively. These balances included the reserve funds required to be maintained by the MHFG Group, which amounted to ¥1,583 billion and ¥1,507 billion at March 31, 2019 and 2020, respectively. At March 31, 2019 and 2020, the MHFG Group had received collateral that can be sold or repledged, with a fair value of ¥16,114 billion and ¥20,663 billion, respectively, of which ¥12,264 billion and ¥18,824 billion, respectively, was sold and repledged. Such collateral was primarily obtained in connection with resale or securities borrowing agreements, and was generally used as collateral for repurchase or securities lending agreements, or to cover short sales. This collateral received isn’t recognized on balance sheet.

Deposits

Deposits	12 Months Ended
	Mar. 31, 2020
Deposits	9. Deposits The balances of time deposits and certificates of deposit issued by domestic offices in amounts of ¥10 million (approximately US$93 thousand at the Federal Reserve Bank of New York’s noon buying rate on March 31, 2020) or more and the balances of these deposits issued by foreign offices in amounts of US$100,000 or more at March 31, 2019 and 2020 are as follows: 2019 2020 (in millions of yen) Domestic offices: Time deposits 16,578,642 14,684,619 Certificates of deposit 5,643,303 7,558,770 Total 22,221,945 22,243,389 Foreign offices: Time deposits 17,606,520 18,008,751 Certificates of deposit 7,695,240 5,723,792 Total 25,301,760 23,732,543 The aggregate amount of demand deposits in overdraft status that have been reclassified as loan balances at March 31, 2019 and 2020 was ¥810 billion and ¥696 billion, respectively. The balance and remaining maturities of time deposits and certificates of deposit issued by domestic and foreign offices at March 31, 2020 are shown in the following table: Time deposits Certificates of deposit Total (in millions of yen) Domestic offices: Due in one year or less 19,660,222 7,418,470 27,078,692 Due after one year through two years 1,676,056 140,300 1,816,356 Due after two years through three years 1,159,144 — 1,159,144 Due after three years through four years 335,659 — 335,659 Due after four years through five years 397,591 — 397,591 Due after five years 212,416 — 212,416 Total 23,441,088 7,558,770 30,999,858 Foreign offices: Due in one year or less 17,936,190 5,565,541 23,501,731 Due after one year through two years 59,530 80,747 140,277 Due after two years through three years 9,536 11,224 20,760 Due after three years through four years 6,624 — 6,624 Due after four years through five years 2,788 66,280 69,068 Due after five years 3,268 — 3,268 Total 18,017,936 5,723,792 23,741,728 Total 41,459,024 13,282,562 54,741,586

Due to trust accounts

Due to trust accounts	12 Months Ended
	Mar. 31, 2020
Due to trust accounts	10. Due to trust accounts MHTB holds assets on behalf of its customers in an agent, fiduciary or trust capacity. Such trust account assets are not the MHFG Group’s proprietary assets and are managed and accounted for separately. However, the cash in individual trust accounts is often placed with MHTB for the customers’ short-term investment needs. These amounts which MHTB owes to the trust accounts are recorded as Due to trust accounts.

Short-term borrowings and long-

Short-term borrowings and long-term debt	12 Months Ended
	Mar. 31, 2020
Short-term borrowings and long-term debt	11. Short-term borrowings and long-term debt Short-term borrowings Short-term borrowings consist of Due to trust accounts, Call money and funds purchased, Payables under repurchase agreements and securities lending transactions, and Other short-term borrowings. Details of Other short-term borrowings at March 31, 2019 and 2020 are as follows: 2019 2020 (in millions of yen) Short-term notes issued by consolidated VIEs of asset-backed commercial paper programs (1) 22,339 54,658 Commercial paper and short-term notes issued by MHFG’s subsidiaries (1)(2) 1,274,382 730,089 Borrowings from the Bank of Japan 508,627 4,002,781 Other 189,478 126,957 Total 1,994,826 4,914,485 Notes: (1) Short-term notes are issued under the laws of Japan in the form of commercial paper. (2) The amounts of commercial paper and short-term notes issued by MHFG’s subsidiaries were ¥941,182 million and ¥333,200 million, respectively, at March 31, 2019, and ¥411,089 million and ¥319,000 million, respectively, at March 31, 2020. Long-term debt Long-term debt with original maturities of more than one year at March 31, 2019 and 2020 is comprised of the following: 2019 2020 (in millions of yen) Obligations under finance leases 25,020 16,250 Loan participation borrowings 142,838 149,398 Senior borrowings and bonds 7,503,032 6,402,157 Subordinated borrowings and bonds 3,858,510 3,778,347 Total 11,529,400 10,346,152 The following table presents the interest rates and maturities of senior borrowings and bonds, and subordinated borrowings and bonds: Interest rates (1) Maturities (2) 2019 2020 (%) (in millions of yen) Senior borrowings and bonds: fixed rate denominated in Japanese yen 0.00-8.10 Apr.2020 Jan.2050 2,057,156 549,647 fixed rate denominated in U.S. dollars 0.00-8.25 Apr.2020 Mar.2048 2,765,247 2,744,713 fixed rate denominated in other currencies 0.02-12.40 Apr.2020 Sep.2039 324,162 609,346 floating rate denominated in Japanese yen 0.00-51.60 Apr.2020 Mar.2050 656,029 606,095 floating rate denominated in U.S. dollars 0.00-37.20 Apr.2020 Dec.2059 1,493,617 1,682,540 floating rate denominated in other currencies 0.00-25.00 Jun.2020 Oct.2030 206,821 209,816 Total 7,503,032 6,402,157 Subordinated borrowings and bonds: fixed rate denominated in Japanese yen 0.39-4.26 Aug.2020 3,442,438 3,370,234 fixed rate denominated in U.S. dollars 4.30-4.70 Jul.2022 Oct.2025 416,072 408,113 Total 3,858,510 3,778,347 Total 11,361,542 10,180,504 Notes: (1) The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2020. (2) Maturity information disclosed is the range of maturities at March 31, 2020. (3) None of the long-term debt issuances above are convertible to common stock. (4) Certain debt agreements permit the MHFG Group to redeem the related debt, in whole or in part, prior to maturity at the MHFG Group’s option on terms specified in the respective agreements. The following is a summary of contractual maturities of long-term debt subsequent to March 31, 2020: (in millions of yen) Fiscal year ending March 31: 2021 559,447 2022 1,430,157 2023 1,234,962 2024 697,214 2025 1,023,243 2026 and thereafter 5,401,129 Total 10,346,152

Other assets and liabilities

Other assets and liabilities	12 Months Ended
	Mar. 31, 2020
Other assets and liabilities	12. Other assets and liabilities The following table sets forth 2019 2020 (in millions of yen) Other assets: Accounts receivable: Receivables from brokers, dealers and customers for securities transactions (1) 1,517,235 783,439 Other 400,676 358,702 Collateral pledged: Collateral pledged for derivative transactions 856,439 1,246,026 Margins provided for futures contracts 159,747 602,039 Other 857,814 941,167 Prepaid pension cost 850,472 711,981 ROU assets (2) — 613,068 Security deposits 123,317 107,294 Loans held for sale 24,921 60,084 Other 485,383 542,079 Total 5,276,004 5,965,879 Other liabilities: Accounts payable: Payables to brokers, dealers and customers for securities transactions (1) 2,572,315 2,161,075 Other 442,776 375,127 Guaranteed trust principal (3) 809,450 824,431 Lease liabilities (2) — 627,250 Collateral accepted: Collateral accepted for derivative transactions 589,411 846,426 Margins accepted for futures contracts 339,863 797,317 Unearned income (4) 126,594 122,072 Other 1,052,297 1,244,697 Total 5,932,706 6,998,395 Notes: (1) Receivables from brokers, dealers and customers for securities transactions included ¥555,938 million and ¥3,136 million of such receivables of consolidated VIEs at March 31, 2019 and 2020, respectively. Payables to brokers, dealers and customers for securities transactions included ¥620,766 million and ¥3,225 million of such payables of consolidated VIEs at March 31, 2019 and 2020, respectively. (2) ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 (3) Guaranteed trust principal, included in All other liabilities in the disclosure about consolidated VIEs in the accompanying balance sheets, is a liability of certain consolidated trust arrangements that meet the definition of a VIE for which the MHFG Group provides guarantees for the repayment of principal. See Note 24 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts. (4) Unearned income is primarily comprised of loan fees received from consumer loan customers when loans are made. This income is deferred and recognized in earnings over the life of the loan.

Preferred stock

Preferred stock	12 Months Ended
	Mar. 31, 2020
Preferred Stock	13. Preferred stock The composition of preferred stock at March 31, 2018, 2019 and 2020 is as follows: March 31, 2018 March 31, 2019 March 31, 2020 Class of stock Authorized Issued Authorized Issued Authorized Issued (number of shares) Class XIV preferred stock 900,000,000 — 900,000,000 — 900,000,000 — Class XV preferred stock 900,000,000 — 900,000,000 — 900,000,000 — Class XVI preferred stock 1,500,000,000 — 1,500,000,000 — 1,500,000,000 — Holders or registered pledgees of preferred stock are entitled to receive annual dividends, and distribution of residual assets of MHFG as set out above at the liquidation value per share, prior to holders of common stock but pari passu among themselves. MHFG may pay up to one-half There was no change in balance of the preferred stock in the fiscal years ended March 31, 2018, 2019 and 2020.

Common stock

Common stock	12 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Common stock	14. Common stock The following table shows the changes in the number of issued shares of common stock during the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (shares) Balance at beginning of fiscal year 25,386,307,945 25,389,644,945 25,392,498,945 Issuance of new shares of common stock due to exercise of stock acquisition rights 3,337,000 2,854,000 — Balance at end of fiscal year 25,389,644,945 25,392,498,945 25,392,498,945

Dividends

Dividends	12 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Dividends	15. Dividends The amount available for dividends under Japan’s Companies Act is based on the amount recorded in MHFG’s non-consolidated period-end Pursuant to the Companies Act, in making a distribution of retained earnings, an entity must set aside in its legal reserve an amount equal to one-tenth In addition to the provision that requires an appropriation for the legal reserve, the Companies Act and Japan’s Banking Act impose certain limitations on the amount available for dividends. Under the Companies Act, MHFG’s maximum amount available for dividends, at March 31, 2020, was ¥1,904,452 million, based on the amount recorded in MHFG’s general books of account under Japanese GAAP. Under the Banking Act and related regulations, MHFG has to meet the minimum capital adequacy requirements. Distributions of retained earnings, which are otherwise distributable to shareholders, are restricted in order to maintain the minimum Common Equity Tier 1 capital ratio of 4.5% for capital adequacy purposes under the rules in Basel III. See Note 17 “Regulatory matters” for further discussion of regulatory capital requirements. Payment of dividends on shares of common stock is also subject to the prior payment of dividends on shares of preferred stock, if any are outstanding.

Accumulated other comprehensive

Accumulated other comprehensive income (loss), net of tax	12 Months Ended
	Mar. 31, 2020
Accumulated other comprehensive income (loss), net of tax	16. Accumulated other comprehensive income (loss), net of tax Changes in each component of AOCI for the fiscal years ended March 31, 2018, 2019 and 2020 are as follows: 2018 2019 2020 (in millions of yen) AOCI, balance at beginning of fiscal year, previously reported 1,521,163 1,741,894 164,021 Cumulative effect of change in accounting principles (1) — (1,535,142 ) (1,052 ) AOCI, balance at beginning of fiscal year, adjusted 1,521,163 206,752 162,969 Net unrealized gains (losses) on available-for-sale Balance at beginning of fiscal year, previously reported 1,461,302 1,556,585 22,019 Cumulative effect of change in accounting principles (1) — (1,525,064 ) — Balance at beginning of fiscal year, adjusted 1,461,302 31,521 22,019 Unrealized holding gains (losses) during year 282,141 (11,358 ) (22,566 ) Less: reclassification adjustments for losses (gains) included in net income (186,858 ) 1,856 (19,045 ) Change during year 95,283 (9,502 ) (41,611 ) Balance at end of fiscal year 1,556,585 22,019 (19,592 ) Foreign currency translation adjustments: Balance at beginning of fiscal year, previously reported (5,535 ) (35,076 ) (58,558 ) Cumulative effect of change in accounting principles (1) — — (1,052 ) Balance at beginning of fiscal year, adjusted (5,535 ) (35,076 ) (59,610 ) Foreign currency translation adjustments during year (26,936 ) (22,737 ) (49,888 ) Less: reclassification adjustments for losses (gains) included in net income (2,605 ) (745 ) (374 ) Change during year (29,541 ) (23,482 ) (50,262 ) Balance at end of fiscal year (35,076 ) (58,558 ) (109,872 ) Pension liability adjustments: Balance at beginning of fiscal year 65,396 220,385 196,446 Unrealized gains (losses) during year 157,737 (17,243 ) (122,219 ) Less: reclassification adjustments for losses (gains) included in net income (2,748 ) (6,696 ) (4,772 ) Change during year 154,989 (23,939 ) (126,991 ) Balance at end of fiscal year 220,385 196,446 69,455 Own credit risk adjustments (2) Balance at beginning of fiscal year, previously reported — — 4,114 Cumulative effect of change in accounting principles (1) — (10,078 ) — Balance at beginning of fiscal year, adjusted — (10,078 ) 4,114 Unrealized gains (losses) during year — 14,293 45,560 Less: reclassification adjustments for losses (gains) included in net income — (101 ) 841 Change during year — 14,192 46,401 Balance at end of fiscal year — 4,114 50,515 Total other comprehensive income (loss), net of tax attributable to MHFG shareholders 220,731 (42,731 ) (172,463 ) AOCI, balance at end of fiscal year 1,741,894 164,021 (9,494 ) Notes: (1) See Note 2 “Issued accounting pronouncements” for further details of the cumulative-effect adjustment for AOCI. (2) The MHFG Group adopted ASU No.2016-01 The following table shows the amounts reclassified out of AOCI into net income during the fiscal year ended March 31, 2020: Before tax (1) Tax effect (2) Net of tax before allocation to noncontrolling interests Net of tax attributable to noncontrolling interests (2) Net of tax attributable to MHFG shareholders (in millions of yen) Amounts reclassified out of AOCI into net income: Affected line items in the consolidated statements of income: Net unrealized gains (losses) on available-for-sale 27,449 (8,410 ) 19,039 6 19,045 Investment gains (losses)—net Foreign currency translation adjustments 374 — 374 — 374 Investment gains (losses)—net Pension liability adjustments 6,618 (1,765 ) 4,853 (81 ) 4,772 Salaries and employee benefits Own credit risk adjustments (1,265 ) 387 (878 ) 37 (841 ) Other noninterest income (expenses) Total 33,176 (9,788 ) 23,388 (38 ) 23,350 Notes: (1) The financial statement line item in which the amounts in the Before tax column are reported in the Consolidated statements of income is listed to the right of the table. (2) The financial statement line items in which the amounts in the Tax effect and the Net of tax attributable to noncontrolling interest columns are reported in the consolidated statements of income are Income tax expense and Net income, respectively.

Regulatory matters

Regulatory matters	12 Months Ended
	Mar. 31, 2020
Regulatory matters	17. Regulatory matters Regulatory capital requirements MHFG, MHBK, and MHTB are subject to regulatory capital requirements administered by the Financial Services Agency in accordance with the provisions of Japan’s Banking Act and related regulations. Certain foreign banking subsidiaries are subject to regulation and control by local supervisory authorities, including central banks. Failure to meet minimum capital requirements may initiate certain mandatory actions by regulators that, if undertaken, could have a direct material effect on the MHFG Group’s consolidated financial condition and results of operations. The capital adequacy guidelines applicable to Japanese banks and bank holding companies with international operations supervised by the Financial Services Agency closely follow the risk-adjusted approach proposed by the Bank for International Settlements and are intended to further strengthen the soundness and stability of Japanese banks. In December 2010, Basel Committee on Banking Supervision (“BCBS”) issued the Basel III rules text, which builds on the International Convergence of Capital Measurement and Capital Standards document (“Basel II”), to strengthen the regulation, supervision and risk management of the banking sector. Basel III text presents the details of global regulatory standards on bank capital adequacy and liquidity. The rules text sets out higher and better-quality capital, better risk coverage, the introduction of a leverage ratio as a backstop to the risk-based requirement, measures to promote the build-up The Financial Services Agency’s revisions to its capital adequacy guidelines became effective from March 31, 2013, which generally reflect the rules in the Basel III text that have been applied from January 1, 2013. There are three primary regulatory capital ratios used to assess capital adequacy: Common Equity Tier 1, Tier 1 and Total risk-based capital ratios. The ratios are comprised of Common Equity Tier 1 capital, Tier 1 capital (Common Equity Tier 1 capital and Additional Tier 1 capital) and total risk-based capital (Tier 1 and Tier 2 capital) divided by risk-weighted assets. Common Equity Tier 1 capital primarily consists of common stock, capital surplus, retained earnings and AOCI. Regulatory adjustments including certain intangible fixed assets, such as goodwill, and defined-benefit pension fund assets will be deducted from Common Equity Tier 1. Additional Tier 1 capital generally consists of Basel III compliant preferred securities and other capital that meets Tier 1 requirements under Basel II standards, net of regulatory adjustments. Tier 2 capital generally consists of Basel III compliant deferred obligations, such as subordinated debts, capital that meets Tier 2 requirements under Basel II standards, certain allowances for credit losses and noncontrolling interests in subsidiaries’ Tier 2 instruments. Under the revised guidelines, the minimum capital adequacy ratio is 8% on both a consolidated and non-consolidated Under Basel III, capital instruments that no longer qualify as Additional Tier 1 capital or Tier 2 capital are being phased out beginning March 2013 by increments of 10% until becoming fully effective in March 2022. The MHFG Group’s existing subordinated debt issued before March 2013 (the amounts thereof included within Tier 2 capital as of March 31, 2020 being ¥337.4 billion) are subject to the phase-out In November 2015, the Financial Services Agency published the revised capital adequacy guidelines and related ordinances to introduce the capital buffer requirements under the Basel III rules for Japanese banks and bank holding companies with international operations, which include the capital conservation buffer, the countercyclical capital buffer and the additional loss absorbency requirements for global systemically important banks (“G-SIBs”) (“D-SIBs”). G-SIBs D-SIBs revised regulatory authorities, if the relevant national authority judges a period of excess credit growth to be leading to the build-up G-SIB D-SIB, requirement Leverage ratio The Leverage Ratio framework is critical and complementary to the risk-based capital framework that will help ensure broad and adequate capture of both on- off-balance Basel III’s leverage ratio is defined as the capital measure (numerator) divided by the exposure measure (denominator) and is expressed as a percentage. The capital measure for the leverage ratio is the Tier 1 capital of the risk-based capital framework, and the exposure measure is the sum of the on-balance off-balance In March 2019, the Financial Services Agency published the revised leverage ratio framework and the minimum leverage ratio is defined as 3% on both a consolidated and non-consolidated The capital requirements and regulatory adjustments are being phased in over a transitional period as follows (italicized percentages indicate those still in transition periods): March 2019 March 2020 March 2021 March 2022 March 2023 Minimum Common Equity Tier 1 capital 4.5 % 4.5 % 4.5 % 4.5 % 4.5 % Minimum Tier 1 capital 6.0 % 6.0 % 6.0 % 6.0 % 6.0 % Minimum total capital 8.0 % 8.0 % 8.0 % 8.0 % 8.0 % Phase out of recognition of capital instruments that no longer qualify as capital 30.0 % 20.0 % 10.0 % 0.0 % 0.0 % Capital conservation buffer 2.5 % 2.5 % 2.5 % 2.5 % 2.5 % Countercyclical capital buffer (1) 0.05 % 0.01 % 0.01 % 0.01 % 0.01 % Additional loss absorbency requirements for G-SIBs D-SIBs (2) 1.0 % 1.0 % 1.0 % 1.0 % 1.0 % Minimum Leverage Ratio 3.0 % 3.0 % 3.0 % 3.0 % 3.5 % (3) Notes: (1) Figures assume that the countercyclical capital buffer will continue to be 0.01% after March 2020. (2) Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB D-SIB (3) This figure includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB If the capital adequacy ratio and leverage ratio of a financial institution falls below the required level, the Financial Services Agency may, depending upon the extent of capital deterioration its total assets, restrict its business operations or other actions that could have a material effect on its financial condition and results of operations. Capital adequacy ratios and leverage ratios accordance 2019 2020 Amount Ratio Amount Ratio (in billions of yen, except percentages) Consolidated: MHFG: Common Equity Tier 1 capital: Required (Note) 4,661 8.05 4,978 8.01 Actual 7,390 12.76 7,245 11.65 Tier 1 capital: Required (Note) 5,529 9.55 5,910 9.51 Actual 9,232 15.94 9,024 14.52 Total risk-based capital: Required (Note) 6,687 11.55 7,152 11.51 Actual 10,918 18.85 10,722 17.25 Leverage Ratio: Required 6,257 3.00 6,629 3.00 Actual 9,232 4.42 9,024 4.08 MHBK: Common Equity Tier 1 capital: Required 2,388 4.50 2,567 4.50 Actual 6,690 12.60 6,501 11.39 Tier 1 capital: Required 3,184 6.00 3,422 6.00 Actual 8,527 16.06 8,275 14.50 Total risk-based capital: Required 4,246 8.00 4,563 8.00 Actual 10,098 19.02 9,865 17.29 Leverage Ratio: Required 5,758 3.00 6,160 3.00 Actual 8,527 4.44 8,275 4.02 MHTB: Common Equity Tier 1 capital: Required 95 4.50 93 4.50 Actual 500 23.67 489 23.64 Tier 1 capital: Required 127 6.00 124 6.00 Actual 501 23.70 489 23.66 Total risk-based capital: Required 169 8.00 165 8.00 Actual 505 23.87 491 23.74 Leverage Ratio: Required 229 3.00 216 3.00 Actual 501 6.55 489 6.79 Non-consolidated: MHBK: Common Equity Tier 1 capital: Required 2,272 4.50 2,403 4.50 Actual 6,363 12.60 6,130 11.47 Tier 1 capital: Required 3,029 6.00 3,204 6.00 Actual 8,199 16.23 7,905 14.80 2019 2020 Amount Ratio Amount Ratio (in billions of yen, except percentages) Total risk-based capital: Required 4,039 8.00 4,272 8.00 Actual 9,757 19.32 9,482 17.75 Leverage Ratio: Required 5,517 3.00 5,884 3.00 Actual 8,199 4.45 7,905 4.03 MHTB: Common Equity Tier 1 capital: Required 94 4.50 93 4.50 Actual 494 23.58 475 23.10 Tier 1 capital: Required 126 6.00 123 6.00 Actual 494 23.58 475 23.10 Total risk-based capital: Required 168 8.00 165 8.00 Actual 498 23.75 477 23.18 Leverage Ratio: Required 227 3.00 214 3.00 Actual 494 6.53 475 6.66 Note: The required ratios disclosed above, at March 31, 2019 and 2020, include the capital conservation buffer G-SIBs D-SIBs MHFG’s securities subsidiary in Japan is also subject to the capital adequacy requirement under Japan’s Financial Instruments and Exchange Act. Under this requirement, securities firms must maintain a minimum capital adequacy ratio of 120% calculated as a percentage of capital accounts less certain assets, as calculated using Japanese GAAP figures, against amounts equivalent to market, counterparty, and basic risks. Specific guidelines are issued as a ministerial ordinance that details the definition of essential components of the capital ratios, including capital, disallowed assets and risks, and related measures. Failure to maintain a minimum capital ratio will trigger mandatory regulatory actions. A capital ratio of less than 140% will call for regulatory reporting and a capital ratio of less than 100% may lead to a temporary suspension of all or part of the business operations and further, to the cancellation of the license to act as a securities broker and dealer. Management believes, as of each latest balance sheet date, that MHFG, MHBK, MHTB, and their securities subsidiary in Japan and foreign banking subsidiaries were in compliance with all capital adequacy requirements to which they were subject.

Earnings per common share

Earnings per common share	12 Months Ended
	Mar. 31, 2020
Earnings per common share	18. Earnings per common share The following table sets forth the computation of basic and diluted earnings per common share for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Net income: Net income attributable to MHFG common shareholders 577,608 84,471 150,195 Effect of dilutive securities — — — Net income attributable to common shareholders after assumed conversions 577,608 84,471 150,195 2018 2019 2020 (thousands of shares) Shares: Weighted average common shares outstanding 25,366,345 25,362,376 25,373,681 Effect of dilutive securities: Stock options and the common shares of MHFG under the stock compensation programs (Note) 7,586 4,522 1,583 Weighted average common shares after assumed conversions 25,373,931 25,366,898 25,375,264 2018 2019 2020 (in yen) Earnings per common share: Basic net income per common share 22.77 3.33 5.92 Diluted net income per common share (Note) 22.76 3.33 5.92 Note: For the fiscal year ended March 31, 2020, the performance-based plan under the stock compensation programs could potentially dilute earnings per common share but were not included in the computation of diluted earnings per common share due to their antidilutive effects.

Income taxes

Income taxes	12 Months Ended
	Mar. 31, 2020
Income taxes	19. Income taxes Income tax expense The following table presents the components of Income tax expense for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Current: Domestic 130,573 116,695 96,231 Foreign 47,020 49,871 52,885 Total current tax expense 177,593 166,566 149,116 Deferred: Domestic 58,078 (162,475 ) (111,341 ) Foreign 1,933 5,244 9,400 Total deferred tax expense (benefit) 60,011 (157,231 ) (101,941 ) Total income tax expense 237,604 9,335 47,175 The preceding table does not reflect the tax effects of items recorded directly in Equity for the fiscal years ended March 31, 2018, 2019 and 2020. The detailed amounts recorded directly in Equity are as follows: 2018 2019 2020 (in millions of yen) Net unrealized gains (losses) on available-for-sale Unrealized gains (losses) 123,186 (3,940 ) (10,012 ) Less: reclassification adjustments (82,828 ) 889 (8,410 ) Total 40,358 (3,051 ) (18,422 ) Pension liability adjustments: Unrealized gains (losses) 66,331 (6,558 ) (52,888 ) Less: reclassification adjustments 190 (2,370 ) (1,765 ) Total 66,521 (8,928 ) (54,653 ) Own credit risk adjustments (Note) Unrealized gains (losses) — 3,033 5,052 Less: reclassification adjustments — (47 ) 387 Total — 2,986 5,439 Total tax effect before allocation to noncontrolling interests 106,879 (8,993 ) (67,636 ) Note: The MHFG Group adopted ASU No.2016-01 Reconciliation of Income tax expense The following table shows a reconciliation of Income tax expense at the effective statutory tax rate to the actual income tax expense for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen, except tax rates) Income before income tax expense 839,298 85,060 153,490 Effective statutory tax rate 30.86 % 30.62 % 30.62 % Income tax calculated at the statutory tax rate 259,007 26,045 46,999 Income not subject to tax (9,312 ) (8,861 ) (7,758 ) Expenses not deductible for tax purposes 1,421 1,389 1,290 Tax rate differentials of subsidiaries (2,696 ) (3,522 ) (5,756 ) Change in valuation allowance (9,102 ) (2,444 ) 5,984 Noncontrolling interest income (loss) of consolidated VIEs (5,928 ) 3,475 14,796 Effect of enacted change in tax rates 6,863 (1) (11 ) (210 ) Change in unrecognized tax benefits — 9,420 — Other (2) (2,649 ) (16,156 ) (3) (8,170 ) Income tax expense 237,604 9,335 47,175 Notes: (1) On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act, which includes a reduction in the U.S. federal corporate income tax rate from 35% to 21%. The decrease in the Group’s balance of net deferred tax assets, reflecting such tax rate reductions, was recognized as an increase to Income tax expense in the fiscal year ended March 31, 2018. The MHFG Group has completed its analysis and accounting under Staff Accounting Bulletin No. 118 for the effects of the Act. (2) Change in undistributed earnings of subsidiaries of ¥(1,972) million and ¥(21,347) million have been reclassified to Other for the fiscal years ended March 31, 2018 and 2019, respectively, in order to conform to the current period’s presentation. (3) In the fiscal year ended March 31, 2019, the MHFG Group derecognized the majority of deferred tax liabilities for undistributed earnings of foreign subsidiaries because the Group has intent and ability to reinvest those earnings indefinitely in certain foreign subsidiaries. Deferred tax assets and liabilities The components of net deferred tax assets (liabilities) at March 31, 2019 and 2020 are as follows: 2019 2020 (in millions of yen) Deferred tax assets: Lease liabilities (1) — 191,873 Allowance for loan losses 122,585 165,665 Premises and equipment 73,944 77,513 Available-for-sale — 5,532 Derivative financial instruments 48,487 4,647 Investments — 3,563 Net operating loss carryforwards (2) 167,755 163,264 Other 216,568 203,004 629,339 815,061 Valuation allowance ( 2 ) (158,581 ) (165,278 ) Deferred tax assets, net of valuation allowance 470,758 649,783 Deferred tax liabilities: Prepaid pension cost and accrued pension liabilities 247,694 202,930 ROU assets (1) — 188,591 Trading securities 9,158 58,266 Investments 198,495 — Available-for-sale 12,426 — Other 61,330 89,157 Deferred tax liabilities 529,103 538,944 Net deferred tax assets (liabilities) (58,345 ) 110,839 Notes: (1) ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 (2) The amount includes ¥107,246 million and ¥101,498 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2019 and 2020, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥88,294 million and ¥86,591 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income. Deferred tax assets and deferred tax liabilities within the same tax jurisdiction have been netted for presentation purposes in the consolidated balance sheets. As of March 31, 2020, the accumulated amount of undistributed earnings that will be indefinitely reinvested and the unrecognized deferred tax liabilities related to such subsidiaries are approximately ¥220 billion and ¥21 billion, respectively. The following table and accompanying footnotes provide a breakdown of deferred tax assets and the valuation allowance recognized in respect of net operating loss carryforwards by tax jurisdiction and by year of expiration as of March 31, 2019 and 2020: Deferred tax assets Valuation allowance Deferred tax assets, net of valuation allowance (in billions of yen) 2019 Japan (1) 111 (92 ) 19 The United States 8 — 8 The United Kingdom (2) 46 (46 ) — Others 3 (2 ) 1 Total 168 (140 ) 28 2020 Japan (3) 110 (92 ) 18 The United States 3 — 3 The United Kingdom (2) 47 (47 ) — Others 3 (2 ) 1 Total 163 (141 ) 22 Notes: (1) ¥107 billion of the Japan deferred tax assets of ¥111 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. (2) The United Kingdom net operating loss carryforwards may be carried forward indefinitely for tax purposes. (3) ¥101 billion of the Japan deferred tax assets of ¥110 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. Determination of valuation allowance In accordance with ASC 740, when the MHFG Group determines whether and to what extent a valuation allowance is needed, the Group considers all available evidence, both positive and negative, to estimate future taxable income. In this regard, the Group considers reversals of existing taxable temporary differences, projected future taxable income (exclusive of reversals of existing temporary differences) and qualifying tax-planning available-for-sale tax-planning available-for-sale Positive evidence includes the Group’s results of operations for the current and preceding years on an overall consolidated basis and for most of the principal subsidiaries. In particular, the strong results of operations in recent years of MHFG’s principal banking subsidiaries in Japan represent positive evidence that can be objectively verified. Negative evidence includes the existence of significant amounts of net operating loss carryforwards or cumulative losses recorded at certain entities, and the expiration of unused net operating loss carryforwards in recent years. A valuation allowance is recorded against deferred tax assets as of the balance sheet date to the extent the Group estimates it is more likely than not that sufficient future taxable income is not available to realize such deferred tax assets. As the Group does not apply a consolidated taxation system, with a few exceptions of certain subsidiaries, deferred tax assets and liabilities are calculated separately for each legal entity. Therefore, changes in the valuation allowance are primarily due to changes in deductible temporary differences, net operating loss carryforwards and the estimated availability of future taxable income sources of each entity. In general, a valuation allowance is recognized against deferred tax assets related to entities that have accumulated significant net operating loss carryforwards. As of March 31, 2020, the Group’s valuation allowance was primarily related to entities in Japan, the United States and the United Kingdom. The valuation allowance was partially recognized in Japan and in the United States, while the valuation allowance was fully recognized in the United Kingdom. The Group determined whether cumulative losses were recognized by aggregating pretax results for the recent three years as part of the analysis of potential indicators of negative evidence. In each tax jurisdiction, certain entities recognized a cumulative loss on the basis of the most recent three years’ pretax results as of March 31, 2020. As it pertains to each entity with a cumulative loss, a valuation allowance was fully recognized against the deferred tax assets if the Group determined there was no positive evidence that overcame the negative evidence. As of March 31, 2020, MHFG’s securities subsidiary in the United Kingdom recorded cumulative losses on the basis of the recent three years’ pretax results and recognized a full valuation allowance, as there was no positive evidence to overcome the negative evidence. MHFG and its principal banking subsidiaries in Japan did not record cumulative losses in the periods presented. Change in valuation allowance The following table presents a roll-forward of the valuation allowance for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Balance at beginning of fiscal year 438,344 163,358 158,581 Changes that directly affected Income tax expense (9,102 ) (2,444 ) 5,984 Changes that did not affect Income tax expense: Expiration of net operating loss carryforwards (264,234 ) — — Others (1,650 ) (2,333 ) 713 Total (265,884 ) (2,333 ) 713 Balance at end of fiscal year 163,358 158,581 165,278 The decrease in the fiscal years ended March 31, 2018 and 2019 of ¥9,102 million and ¥2,444 million, respectively, in the valuation allowance that directly affected Income tax expense was primarily related to an increase of the realizability of deferred tax assets of MHFG’s subsidiaries. The increase in the fiscal year ended March 31, 2020 of ¥5,984 million in the valuation allowance that directly affected Income tax expense was primarily related to a decrease of the realizability of deferred tax assets of MHFG and its subsidiaries. Net operating loss carryforwards At March 31, 2020, the MHFG Group had net operating loss carryforwards totaling ¥637 billion. These carryforwards are scheduled to expire as follows: Net operating loss carryforwards (in billions of yen) Fiscal year ending March 31: 2021 — 2022 — 2023 6 2024 3 2025 — 2026 and thereafter (Note) 628 Total 637 Note: Including the net operating loss carryforwards which may be carried forward indefinitely in the United Kingdom. In addition, included in the net operating loss carryforwards in the above table are MHSC’s net operating loss carryforwards of ¥333 billion resulting mainly from the reversal of an outside basis difference related to certain foreign subsidiaries due to their organizational restructuring. The tax loss was recorded at MHSC in accordance with Japanese tax law. The net operating loss carryforwards due to this restructuring will expire during the fiscal year ending March 31, 2026. Uncertainty in income tax The following table is a roll-forward of unrecognized tax benefits for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Total unrecognized tax benefits at beginning of fiscal year 1,867 2,345 12,323 Gross amount of increases related to positions taken during prior years 224 9,550 199 Gross amount of increases related to positions taken during the current year 351 330 328 Amount of decreases related to settlements — — (9,420 ) Foreign exchange translation (97 ) 98 (56 ) Total unrecognized tax benefits at end of fiscal year 2,345 12,323 3,374 The total amount of unrecognized tax benefits including ¥888 million, ¥2,164 million and ¥1,477 million of interest and penalties was ¥2,345 million, ¥12,323 million and ¥3,374 million at March 31, 2018, 2019 and 2020, respectively, which would, if recognized, affect the Group’s effective tax rate. The Group classifies interest and penalties accrued relating to unrecognized tax benefits as Income tax expense. The MHFG Group is currently subject to ongoing tax audits in some jurisdictions. The oldest years open to tax audits in Japan, the United States and the United Kingdom are 2011, 2002 and 2016, respectively

Pension and other employee bene

Pension and other employee benefit plans	12 Months Ended
	Mar. 31, 2020
Pension and other employee benefit plans	20. Pension and other employee benefit plans Severance indemnities and pension plans MHFG and certain subsidiaries sponsor and offer their employees, other than directors and corporate auditors, contributory and non-contributory lump-sum lump-sum Certain foreign offices and subsidiaries have defined contribution plans and/or defined benefit plans, of which disclosures are combined with those for domestic benefit plans, as they are not significant and those plans don’t use significantly different assumptions. MHFG and certain subsidiaries have several defined contribution plans. The costs recognized in respect of contributions to the plans for the fiscal years ended March 31, 2018, 2019 and 2020 were ¥2,511 million, ¥3,217 million and ¥3,142 million, respectively. Pension plans are not fully integrated among subsidiaries of MHFG and plan assets are managed separately by each plan. Net periodic benefit cost and funded status The following table presents the components of net periodic cost of the severance indemnities and pension plans for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Service cost-benefits earned during the fiscal year 43,649 43,698 45,697 Interest costs on projected benefit obligations 7,471 6,933 5,590 Expected return on plan assets (34,916 ) (38,518 ) (40,551 ) Amortization of prior service cost (benefits) 214 152 121 Amortization of net actuarial loss (gain) 411 (7,886 ) (5,873 ) Special termination benefits 3,960 2,929 9,793 Net periodic benefit cost 20,789 7,308 14,777 Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before-tax 2019 2020 (in millions of yen) Net actuarial gain (loss) (21,300 ) (169,963 ) Amortization of net actuarial loss (gain) (7,886 ) (5,873 ) Prior service benefits (cost) (109 ) (2,734 ) Amortization of prior service cost (benefits) 152 121 Total recognized in other comprehensive income (loss) before-tax (29,143 ) (178,449 ) As of March 31, 2020, the amounts in Accumulated other comprehensive income (loss), which will be amortized as prior service costs and actuarial loss over the next fiscal year, are estimated to be ¥409 million and ¥1,642 million, respectively. Weighted-average assumptions used to determine benefit obligations and net periodic benefit cost are as follows: 2018 2019 2020 Weighted-average assumptions used to determine benefit obligations at fiscal year end: Discount rates 0.43 % 0.34 % 0.37 % Rates of increase in future compensation levels 1.80-4.80 % 1.80-4.80 % 1.80-4.80 % Weighted-average assumptions used to determine net periodic benefit cost during the year: Discount rates 0.47 % 0.43 % 0.34 % Rates of increase in future compensation levels 1.80-4.80 % 1.80-4.80 % 1.80-4.80 % Expected rates of return on plan assets 1.58 % 1.60 % 1.68 % In estimating the discount rates, the MHFG Group uses interest rates on high-quality fixed-income government and corporate bonds. The durations of these bonds closely match those of the benefit obligations. Assumed discount rates are reevaluated at each measurement date. The expected rate of return for each asset category is based primarily on various aspects of the long-term prospects for the economy that include historical performance and the market The following table sets forth the combined funded status and amounts recognized in the accompanying consolidated balance sheets at March 31, 2019 and 2020 for the plans of MHFG and its subsidiaries: 2019 2020 (in millions of yen) Change in benefit obligations: Benefit obligations at beginning of fiscal year 1,559,356 1,590,818 Service cost 43,698 45,697 Interest cost 6,933 5,590 Plan participants’ contributions 1,229 1,200 Amendments 109 2,734 Actuarial loss (gain) 49,085 4,507 Foreign exchange translation (817 ) (5,605 ) Benefits paid (52,618 ) (52,902 ) Lump-sum (16,157 ) (20,743 ) Benefit obligations at end of fiscal year 1,590,818 1,571,296 Change in plan assets: Fair value of plan assets at beginning of fiscal year 2,405,730 2,413,556 Actual return (negative return) on plan assets 66,652 (125,549 ) Foreign exchange translation (390 ) (4,268 ) Partial withdrawal of assets from employee retirement benefits trusts (Note) (27,534 ) — Employer contributions 20,487 20,587 Plan participants’ contributions 1,229 1,200 Benefits paid (52,618 ) (52,902 ) Fair value of plan assets at end of fiscal year 2,413,556 2,252,624 Funded status 822,738 681,328 Amounts recognized in the consolidated balance sheets consist of: Prepaid pension cost 850,472 711,981 Accrued pension liability (27,734 ) (30,653 ) Net amount recognized 822,738 681,328 Amounts recognized in Accumulated other comprehensive income (loss) before-tax Prior service benefits (cost) (1,309 ) (3,914 ) Net actuarial gain (loss) 262,044 86,200 Net amount recognized 260,735 82,286 Note: During the fiscal year ended March 31, 2019, a subsidiary of MHFG partially withdrew assets from employee retirement benefit trusts, which were established for the payment of employees’ severance pay and retirement pensions. Overall, the trusts remain in overfunded status as of March 31, 2019. No gains or losses have been recognized as a result of this transaction. The aggregated accumulated benefit obligations of these plans were ¥1,590,818 million and ¥1,571,296 million, as of March 31, 2019 and 2020, respectively. The defined benefit plans generally employ a multi-variable and non-linear The following table shows the projected benefit obligations and the fair value of plan assets for the plans of MHFG and its subsidiaries with projected benefit obligations in excess of plan assets, and the accumulated benefit obligations and the fair value of plan assets for the plans with accumulated benefit obligations in excess of plan assets at March 31, 2019 and 2020: 2019 2020 (in millions of yen) Plans with projected benefit obligations in excess of plan assets: Projected benefit obligations 61,579 63,619 Fair value of plan assets 33,845 32,966 Plans with accumulated benefit obligations in excess of plan assets: Accumulated benefit obligations 61,579 63,619 Fair value of plan assets 33,845 32,966 Note: The plans with projected benefit obligations in excess of plan assets include those with accumulated benefit obligations in excess of plan assets. Investment policies and asset allocation In managing plan assets, the MHFG Group determines the appropriate levels of risk that the Group can assume under the given circumstances to maximize the investment returns from a long-term perspective while ensuring that sufficient funds will be available to plan participants and beneficiaries. Generally, the investment returns are relative to the risks involved. In considering the maximum levels of risk that the MHFG Group can assume, it primarily considers the following factors: the employers’ burden of maintaining the benefit plans based on the design of the plans and future plan contributions, the age distribution of the plan participants and beneficiaries, the financial conditions of the employers, and the employers’ ability to absorb future variability in plan premiums. The long-term asset allocation to each asset category such as Japanese equity securities, Japanese debt securities, foreign equity securities and foreign debt securities is determined based upon the optimal portfolio, which is estimated to yield the maximum return within the range of an acceptable level of risk. Additionally, the asset allocation is reviewed whenever there are large fluctuations in pension plan liabilities caused by modifications of pension plans, or there are changes in the market environment. When selecting an investment in each asset category, the MHFG Group takes into consideration credit standing of an investee, concentration of credit risk to a certain investee and liquidity of a financial instrument among other things. The investments in each asset category are further diversified across funds, strategies and sectors along with other things. There is no significant investment in a single investee except Japanese government bonds. Certain subsidiaries of MHFG established employee retirement benefit trusts and transferred their assets to the trusts as plan assets. These assets are separated from the employer’s proprietary assets for the payment to the plan beneficiaries. The assets held in these trusts are primarily Japanese equity securities and have been entrusted directly to qualified trustees including trust banks. MHFG and certain subsidiaries’ target allocation for the plan assets, excluding those of the employee retirement benefit trusts, at March 31, 2020 is as follows: Asset category Asset ratio Japanese equity securities 5.00 % Japanese debt securities 34.00 % Foreign equity securities 25.00 % Foreign debt securities 23.00 % General account of life insurance companies 11.00 % Other 2.00 % Total 100.00 % Note: General account of life insurance companies is a contract with life insurance companies which guarantees payments of principal and predetermined interest payments. Fair value of plan assets The following table presents the fair value of plan assets of MHFG and its subsidiaries at March 31, 2019 and 2020, by asset class. For the detailed information on fair value measurements, including descriptions of Level 1, 2 and 3 of the fair value hierarchy and the valuation methodologies, see Note 27 “Fair value.” 2019 2020 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in billions of yen) Japanese equity securities: Common stocks (1) 1,317 — — 1,317 1,194 — — 1,194 Pooled funds (2) 11 4 — 15 10 4 — 14 Japanese debt securities: Government bonds 190 — — 190 196 — — 196 Pooled funds (2) — 10 — 10 — 9 — 9 Other — 24 — 24 — 23 — 23 Foreign equity securities: Common stocks 120 — — 120 101 — — 101 Pooled funds (2) — 5 — 5 — 4 — 4 Foreign debt securities: Government bonds 178 6 — 184 188 7 — 195 Pooled funds (2) — 10 — 10 — 11 — 11 Other — 18 — 18 — 20 — 20 General account of life insurance companies (3) — 111 — 111 — 111 — 111 Other 79 (4) 4 — 83 68 (4) 1 — 69 Plan assets measured at net asset value (5) 327 306 Total assets at fair value 1,895 192 — 2,414 1,757 190 — 2,253 Notes: (1) This class represents equity securities held in the employee retirement benefit trusts of ¥1,317 billion and ¥1,194 billion carried at fair value at March 31, 2019 and 2020, respectively, which are well-diversified across industries. (2) These classes primarily include pension investment fund trusts. Investments in these classes are generally measured at fair value and can be redeemed within a short-term period upon request. (3) Investments in this class are measured at conversion value, which is equivalent to fair value. (4) Amounts primarily include cash and short-term assets carried at fair value. (5) In accordance with ASC 820, certain plan assets that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. There were no returns on and purchases and sales of Level 3 assets during the fiscal years ended March 31, 2019 and 2020. Contributions The total contribution of approximately ¥50 billion is expected to be paid to the pension plans during the fiscal year ending March 31, 2021, based on the current funded status and expected asset return assumptions. Estimated future benefit payments The following table presents forecasted benefit payments including the effect of expected future service for the fiscal years indicated: (in millions of yen) Fiscal year ending March 31: 2021 70,325 2022 70,623 2023 71,165 2024 72,469 2025 73,118 2026-2030 346,908

Stock-based compensation

Stock-based compensation	12 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-based compensation	21. Stock-based compensation Stock options MHFG, MHBK, MHTB and MHSC have stock options, in the form of stock acquisition rights, for directors (excluding the outside directors) and executive officers of the respective companies (hereinafter referred to collectively as the “Directors”). In this plan (“MHFG Stock Plan”), 1,000 shares of MHFG common stock shall be issued or transferred upon exercise of each of the stock acquisition rights. The exercise price is 1 yen per share. The contractual term of the stock acquisition rights is 20 years. A holder may exercise the stock acquisition rights only after the date on which such holder loses the status as a Director of MHFG, MHBK, MHTB or MHSC. The following is a roll-forward of MHFG Stock Plan for the fiscal year ended March 31, 2020: Number of shares Weighted-average exercise price Weighted-average remaining contractual term Aggregate intrinsic value (in yen) (in years) (in millions of yen) Outstanding at beginning of fiscal year 4,245,000 1 Exercised during fiscal year 2,968,000 1 Outstanding at end of fiscal year 1,277,000 1 13.91 157 Exercisable at end of fiscal year — — — — There were no non-vested In May 2015, MHFG discontinued the stock option program. Thereafter, MHFG has not issued any new stock options. Stock compensation programs MHFG, MHBK, MHTB and MHSC introduced a position-based stock compensation program for Directors (“Stock Compensation I”) in July 2018 and a performance-based stock compensation program for Directors (“Stock Compensation II”) in May 2015. The stock compensation is paid in the form of shares of common stock of MHFG, acquired from the stock market through a trust, with the aim of aligning the Directors’ interests with those of the shareholders and increasing the incentive to enhance corporate value. Stock Compensation I, in principle, is paid at the time of retirement of the individual Directors in the form of common stock of MHFG and cash, calculated based on their position. Stock Compensation II is calculated and then paid to the Directors based on MHFG Group’s immediate, prior period-performance, the recent performance of organizations that the Directors are in charge of, and the performance of each Director. The payment in the form of common stock of MHFG and cash is deferred over a three-year, graded-vesting period. The amount of Stock Compensation I and II is subject to reduction or forfeiture. The following table presents activities related to the stock compensation programs for the fiscal years ended March 31, 2019 and 2020: Stock Compensation I Stock Compensation II 2019 Number of shares Weighted-average grant-date fair value Number of shares Weighted-average grant-date fair value (per share in yen) (per share in yen) Nonvested at the beginning of the year — — 13,319,406 182.04 Granted during fiscal year 3,770,065 189.24 6,906,635 189.24 Vested during fiscal year 3,770,065 189.24 5,068,949 187.48 Forfeited during fiscal year — — — — Nonvested at the end of the year — — 15,157,092 183.50 Stock Compensation I Stock Compensation II 2020 Number of shares Weighted-average grant-date fair value Number of shares Weighted-average grant-date fair value (per share in yen) (per share in yen) Nonvested at the beginning of the year — — 15,157,092 183.50 Granted during fiscal year 5,748,997 159.59 3,281,003 159.59 Vested during fiscal year 5,748,997 159.59 7,014,809 182.07 Forfeited during fiscal year — — — — Nonvested at the end of the year — — 11,423,286 177.51 The following table presents the total fair value of the stock compensation that vested and the total amount of the common stock acquired from the stock market by the trustee for the fiscal years ended March 31, 2019 and 2020: 2019 2020 Stock Compensation I Stock Compensation II Stock Compensation I Stock Compensation II (in millions of yen) Fair value of vested shares 713 930 917 1,090 Common stock shares acquired 713 1,307 917 524 For both programs, the stock-based compensation cost is determined based on the fair value of MHFG’s common stock as of grant date. For Stock Compensation I and II, the liability related to the cash-based compensation cost is remeasured at each reporting date based on the fair value of MHFG’s common stock. For Stock Compensation II, the stock-based compensation costs are recognized evenly over the graded-vesting period, which is three years. For Stock Compensation I, as the program is effectively vested on the grant date, the stock-based compensation cost is recognized on the grant date. The following table presents the compensation cost recognized in the stock compensation programs for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Stock Compensation I — 713 917 Stock Compensation II 868 1,287 1,247 With regard to Stock Compensation II, the total compensation cost related to non-vested

Derivative financial instrument

Derivative financial instruments	12 Months Ended
	Mar. 31, 2020
Derivative financial instruments	22. Derivative financial instruments The MHFG Group enters into derivative financial instruments in response to the diverse needs of customers, to manage the risk related to the assets and liabilities of the MHFG Group, as part of its asset and liability management, and for proprietary trading purposes. The MHFG Group is exposed primarily to market risk associated with interest rate, commodity, foreign currency, and equity products. Market risk arises from changes in market prices or indices, interest rates and foreign exchange rates that may result in an adverse change in the market value of the financial instrument or an increase in its funding costs. Exposure to market risk is managed by imposing position limits and monitoring procedures and by initiating hedging transactions. In addition to market risk, the MHFG Group is exposed to credit risk associated with counterparty default or nonperformance in respect of transactions. Counterparty credit risk arises when a counterparty fails to perform according to the terms and conditions of the contract and the value of the underlying collateral held, if applicable, is not sufficient to recover resulting losses. The exposure to counterparty credit risk is measured by the fair value of all derivatives and its potential exposure at the balance sheet dates. The exposure to counterparty credit risk is managed by entering into legally enforceable master netting agreements to mitigate the overall counterparty credit risk, requiring underlying collateral and guarantees based on an individual credit analysis of each obligor and evaluating the credit features of each instrument. In addition, credit approvals, limits and monitoring procedures are also imposed. Notional and fair value amounts of derivative instruments The following table summarizes the notional and fair value amounts of derivative instruments outstanding as of March 31, 2019 and 2020. The fair values of derivatives are presented on a gross basis ; Fair value Derivative receivables (2) Derivative payables (2) 2019 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,052,267 — 5,786 — 5,610 Foreign exchange contracts 166,383 — 1,959 — 1,758 Equity-related contracts 5,181 — 125 — 142 Credit-related contracts 2,939 — 18 — 17 Other contracts 438 — 16 — 14 Total 1,227,208 — 7,904 — 7,541 Fair value Derivative receivables (2) Derivative payables (2) 2020 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,123,546 — 7,232 — 6,788 Foreign exchange contracts 185,359 — 2,926 — 2,899 Equity-related contracts 6,684 — 310 — 266 Credit-related contracts 4,676 — 30 — 29 Other contracts 400 — 38 — 39 Total 1,320,665 — 10,536 — 10,021 Notes: (1) Notional amount includes the sum of gross long and gross short third-party contracts. (2) Derivative receivables and payables are recorded in Trading account assets and Trading account liabilities, respectively. The MHFG Group provided and/or accepted cash collateral for derivative transactions under master netting agreements. The cash collateral, which was not offset against derivative positions, was included in Other assets and Other liabilities, respectively, of which the amounts were ¥856 billion and ¥589 billion at March 31, 2019, and ¥1,246 billion and ¥846 billion at March 31, 2020, respectively. Hedging activities In order to qualify for hedge accounting, a derivative must be considered highly effective at reducing the risk associated with the exposure being hedged. Each derivative must be designated as a hedge, with documentation of the risk management objective and strategy, including identification of the hedging instrument, the hedged item and the risk exposure, and how effectiveness is to be assessed prospectively and retrospectively. The extent to which a hedging instrument is effective at achieving offsetting changes in fair value or cash flows must be assessed at least quarterly. The MHFG Group’s hedging activities include fair value and net investment hedges. Fair value hedges The MHFG Group primarily uses forward contracts to modify exposure to changes in the fair value of Equity securities. The Group adopted ASU No.2016-01 Before the adoption of the ASU, for qualifying fair value hedges, all changes in the fair value of the derivative and the corresponding hedged item relating to the risk being hedged were recognized in earnings in Investment gains (losses)—net. The change in fair value of the portion of the hedging instruments excluded from the assessment of hedge effectiveness was recorded in Trading account gains (losses)—net. No ineffectiveness existed because the MHFG Group chose to exclude changes in the differences between the spot and the forward prices from the effectiveness test. If the hedge relationship was terminated, the fair value adjustment to the hedged item continued to be reported as part of the basis of the item. The fair value adjustment was recognized in earnings upon the sale of the hedged item. The following table summarizes gains and losses information related to fair value hedges for the fiscal year ended March 31, 2018: Gains (losses) recorded in income 2018 Derivatives Hedged items Hedge ineffectiveness Net gain (loss) excluded from assessment of effectiveness (in millions of yen) Equity-related contracts (23,832 ) 19,631 — (4,201 ) Total (23,832 ) 19,631 — (4,201 ) Net investment hedges The MHFG Group uses forward foreign exchange contracts and foreign currency-denominated debt instruments to protect the value of net investments in non-Japanese The following table summarizes gains and losses information related to net investment hedges for the fiscal years ended March 31, 2018, 2019 and 2020: Gains (losses) recorded in other comprehensive income (“OCI”) 2018 2019 2020 (in millions of yen) Financial instruments hedging foreign exchange risk 60 7,512 418 Total 60 7,512 418 Note: Related to the net investment hedges, gains (losses) of ¥186 million and ¥(1,336) million were reclassified from Accumulated other comprehensive income to earnings for the fiscal years ended March 31, 2019 and 2020, respectively. No amount related to the net investment hedges was reclassified from Accumulated other comprehensive income to earnings for the fiscal year ended March 31, 2018. Derivative instruments not designated or qualifying as hedges The MHFG Group enters into the following derivative transactions that do not qualify for hedge accounting with a view to implementing risk management strategies: (1) interest-rate swap transactions for the purpose of economically managing the interest-rate risks in deposits, loans etc., (2) currency swap transactions for the purpose of economically managing the foreign exchange risk of these assets, and (3) credit derivatives for the purpose of economically managing the credit risk in loans, residential mortgage-backed securities (“RMBS”), commercial mortgage-backed securities (“CMBS”), collateralized loan obligations (“CLO”) and other similar assets. Such derivatives are accounted for as trading positions. The changes in fair value of these instruments are primarily recorded in Trading account gains (losses)—net, even though they are used to mitigate or transform the risk of exposures arising from banking activities. The net gains (losses) resulting from changes in the fair value of certain credit derivatives where the Group purchases protection to mitigate its credit risk exposure, related to its corporate loan portfolio, is recorded in Other noninterest income (expenses). The following table summarizes gains and losses on derivatives not designated or qualifying as hedges during the fiscal years ended March 31, 2018, 2019 and 2020: Gains (losses) recorded in income 2018 2019 2020 (in millions of yen) Interest rate contracts (63,260 ) 127,242 388,289 Foreign exchange contracts 61,046 6,748 (111,920 ) Equity-related contracts (1) (94,607 ) 37,875 217,744 Credit-related contracts (2) (2,830 ) (467 ) 8,046 Other contracts 6,330 (1,455 ) (21,143 ) Total (93,321 ) 169,943 481,016 Notes: (1) The net gains (losses) excluded from the assessment of the effectiveness of fair value hedges is not included in the above table. (2) Amounts include the net gains (losses) of ¥(754 ) ) Credit derivatives A credit derivative is a bilateral contract between a seller and a buyer of protection against the credit risk of a particular entity. Credit derivatives generally require that the seller of credit protection make payments to the buyer upon the occurrence of predefined credit events, which include bankruptcy, dissolution or insolvency of the referenced entity. The MHFG Group either purchases or writes protection on either a single name or a portfolio of reference credits. The Group enters into credit derivatives to help mitigate credit risk in its corporate loan portfolio and other cash positions, to take proprietary trading positions, and to facilitate client transactions. The notional amount of credit derivatives represents the maximum potential amount of future payments the seller could be required to make. If the predefined credit event occurs, the seller will generally have a right to collect on the underlying reference credit and the related cash flows, while being liable for the full notional amount of credit protection to the buyer. The Group manages credit risk associated with written protection by purchasing protection with identical or similar underlying reference credits, which substantially offsets its exposure. Thus, the notional amount is not necessarily a reliable indicator of the Group’s actual loss exposure. The following table summarizes the notional and fair value amounts of credit derivatives at March 31, 2019 and 2020: 2019 2020 Notional amount Fair value Notional amount Fair value (in billions of yen) Credit protection written: Investment grade 1,266 12 1,400 (5 ) Non-investment 199 3 416 — Total 1,465 15 1,816 (5 ) Credit protection purchased 1,628 (14 ) 3,028 6 Note: The rating scale is based upon either the external ratings or the internal ratings of the underlying reference credit. The lowest investment grade rating is considered to be BBB - non-investment Non-investment The following table shows the maximum potential amount of future payments for credit protection written by expiration period at March 31, 2019 and 2020: Maximum payout/Notional amount 2019 2020 (in billions of yen) One year or less 326 270 After one year through five years 1,057 1,368 After five years 82 178 Total 1,465 1,816 Note: The maximum potential amount of future payments is the aggregate notional amount of the credit derivatives where the Group wrote the credit protection, and it has not been reduced by the effect of any amounts that the Group may possibly collect on the underlying assets and the related cash flows, nor netted against that of credit protection purchased. Credit-related contingent features Certain of the MHFG Group’s derivative instruments contain provisions that require the Group’s debt to maintain an investment grade credit rating from the major credit rating agencies. If the Group’s debt credit rating were to fall below investment grade, the counterparties to the derivative instruments could request immediate payment or demand immediate and ongoing full overnight collateralization on derivative instruments which are in net liability positions for the Group. The following table shows the quantitative information about derivative instruments with credit-risk-related contingent features at March 31, 2019 and 2020: 2019 2020 (in billions of yen) Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions 511 888 Collateral provided to counterparties in the normal course of business 489 818 Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered 22 70

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Mar. 31, 2020
Commitments and contingencies	23. Commitments and contingencies Obligations under guarantees The MHFG Group provides guarantees or indemnifications to counterparties to enhance their credit standing and enable them to complete a variety of business transactions. A guarantee represents an obligation to make payments to third parties if the counterparty fails to fulfill its obligation under a borrowing arrangement or other contractual obligation. The types of guarantees under ASC 460, “Guarantees” (“ASC 460”) provided by the MHFG Group are described below. Performance guarantees Performance guarantees are issued to guarantee customers’ performance under contractual arrangements such as a tender bid on a construction project or the completion of a construction project. Guarantees on loans Guarantees on loans include obligations to guarantee the customers’ borrowing contracts. The MHFG Group is required to make payments to the guaranteed parties in the event that customers fail to fulfill obligations under the contracts. Guarantees on securities Guarantees on securities include obligations to guarantee securities, such as bonds issued by customers. Other guarantees Other guarantees include obligations to guarantee customers’ payments, such as tax payments. Guarantees for the repayment of trust principal The MHFG Group provides certain trust products trust assets to minimize exposures against losses from the guarantees for the repayment of trust principal, including writing-off Part of the trust account profits is set aside as a reserve in trust accounts to absorb losses in the trust asset portfolios in accordance with relevant Japanese laws concerning the trust business and/or trust agreements. Statutory reserves for loan trusts and reserves for jointly operated designated money trusts are calculated based on the trust principal or the balance of loans and other assets in the trust accounts. Since the probability of principal indemnification is considered to be remote, the MHFG Group had no related reserve for credit losses recorded in its consolidated financial statements. Liabilities of trust accounts The MHFG Group, as trustee, may enter into an agreement with a third party who is not the party to the relevant trust agreement to the extent necessary to handle the trust affairs for the purpose of fulfilling the objectives of the trust and, as such, the trustee shall be allowed to assume certain liabilities. Pursuant to Japanese trust-related laws, the trustee is ultimately liable to pay those liabilities out of its proprietary assets in the event that the trust assets are insufficient to cover those liabilities. The amount of trust liabilities rarely exceeds the amount of trust assets and, therefore, those liabilities are generally covered by the corresponding trust assets. To avoid the demand for payment out of the proprietary assets, the trustee can enter into a special covenant of limited liability under which the trust creditors agree to limit the trustee’s liability to the value of the trust assets and to waive the right for compulsory execution against the trustee’s proprietary assets. The MHFG Group regularly monitors the condition of trust accounts to minimize exposures against making payment. The amounts of such liabilities in the trust accounts, excluding those with the special covenant of limited liability, are presented in the tables below. Liabilities of trust accounts principally include obligations to return collateral under security lending transactions and other transactions. Derivative financial instruments Certain written options and credit default swaps are deemed guarantees pursuant to the definition of guarantees in ASC 460 if these contracts require the MHFG Group to make payments to counterparties based on changes in an underlying instrument or index that is related to an asset, a liability, or an equity security of the counterparties. The MHFG Group’s payments could involve a gross settlement or a net settlement. Because it is difficult in practice to determine whether the counterparty has the asset, the liability or the equity security relating to the underlying, the MHFG Group has decided to include all credit default swaps and written options, excluding written options outside the scope of ASC 460, in the guarantee disclosures. The MHFG Group records all guarantees and similar obligations subject to ASC 460 at fair value in the consolidated balance sheets at the inception of the guarantee. The total carrying amount of guarantees and similar obligations at March 31, 2019 and 2020 was ¥109 billion and ¥521 billion, respectively, and was included in Other liabilities and Trading account liabilities. The total includes the carrying amounts of derivatives that are deemed to be guarantees, which amounted to ¥90 billion and ¥502 billion at March 31, 2019 and 2020, respectively. The table below summarizes the remaining term and maximum The MHFG Group, when necessary, requires collateral such as cash, investment securities and real estate or third-party guarantees depending on the amount of credit risk involved, and employs means such as sub-participation 2019 Maximum potential/Contractual Amount by expiration period One year or less After one year After five years (in billions of yen) Performance guarantees 2,307 1,265 878 164 Guarantees on loans 289 164 46 79 Guarantees on securities 145 91 54 — Other guarantees 2,324 1,447 834 43 Guarantees for the repayment of trust principal 65 — 47 18 Liabilities of trust accounts 362 61 148 153 Derivative financial instruments 14,170 5,807 6,434 1,929 2020 Maximum potential/Contractual or Notional amount Amount by expiration period One year or less After one year through five years After five years (in billions of yen) Performance guarantees 2,456 1,511 735 210 Guarantees on loans 301 204 34 63 Guarantees on securities 110 22 88 — Other guarantees 2,314 1,925 319 70 Guarantees for the repayment of trust principal 59 — 42 17 Liabilities of trust accounts 446 80 201 165 Derivative financial instruments 21,756 11,045 7,951 2,760 The table below presents the maximum potential amount of future payments of performance guarantees, guarantees on loans, guarantees on securities and other guarantees classified based on internal ratings at March 31, 2019 and 2020: 2019 2020 (in billions of yen) Investment grade 4,124 4,233 Non-investment 941 948 Total 5,065 5,181 Note: Investment grade in the internal rating scale generally corresponds to BBB- Other off-balance-sheet In addition to guarantees, the MHFG Group issues other off-balance-sheet Commitments to extend credit Commitments to extend credit are legally binding agreements to lend to customers on demand. They usually have set maturity dates. These agreements differ from guarantees in that they are generally revocable or contain provisions that enable the MHFG Group to avoid payment or reduce the amount of credit extended under certain conditions, such as the deterioration of the borrower’s financial condition or other reasonable conditions. The MHFG Group monitors the financial condition of the potential borrowers throughout the commitment period to determine whether additional collateral or changes in the terms of the commitment are necessary. Since many of these commitments to extend credit expire without being drawn upon, the total commitment amounts do not necessarily represent future cash requirements. Commitments to invest in securities Commitments to invest in securities include legally binding contracts to make additional contributions to investment funds, such as private equity funds in accordance with the terms of investment agreements. Commercial letters of credit Commercial letters of credit are issued in connection with customers’ trade transactions. Normally, the customers cannot receive the goods until they make payment to a bank, and therefore these commercial letters of credit are collateralized by the underlying goods. Upon issuance of commercial letters of credit, the MHFG Group monitors the credit risk associated with these transactions to determine if additional collateral is required. The table below summarizes the contractual amounts with regard to these undrawn commitments at March 31, 2019 and 2020: 2019 2020 (in billions of yen) Commitments to extend credit (Note) 76,857 76,633 Commercial letters of credit 778 690 Total 77,635 77,323 Note: Commitments to extend credit include commitments to invest in securities. Allowance for losses on off-balance-sheet The amounts of allowance for losses on off-balance-sheet Legal proceedings and investigations The MHFG Group is involved in normal collection proceedings initiated by the Group, other legal proceedings and investigations in the ordinary course of business. In accordance with ASC 450, the Group recognizes a liability for loss contingencies arising from such proceedings and investigations when a loss is probable and the loss amount or the range of the loss can be reasonably estimated. If a loss does not meet this condition but is reasonably possible, the Group does not recognize a liability but discloses the detail of such proceedings and investigations. Based on the information available as of the date of the consolidated financial statements, the Group believes that the outcome of the collection, legal proceedings and investigations will not have a significant adverse effect on the consolidated financial statements. Leases The MHFG Group is obligated under a number of lease arrangements. The Group’s lessee arrangements mainly consist of operating leases for real estate, such as office space, including its head office, and branches. Finance leases are not significant. Some of the Group’s operating leases include variable lease payments. The following table presents the consolidated balance sheet information related to operating leases as of March 31, 2020: As of March 31, 2020 (in millions of yen, except for remaining ROU assets (Note) 613,068 Lease liabilities (Note) 627,250 Weighted average: Remaining lease term 15.7 years Discount rate 0.55 % Note: ROU assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets. The following table presents lease cost and supplemental information related to operating leases for the fiscal year ended March 31, 2020: Fiscal year ended March 31, 2020 (in millions of yen) Lease cost (Note) 126,840 ROU assets obtained in exchange for new lease liabilities 60,047 Operating cash flows 102,066 Note: Lease cost for operating leases are included in Occupancy expenses The following table shows future lease payments under operating leases as of March 31, 2020: As of March 31, 2020 (in millions of yen) Fiscal year ending March 31: 2021 93,997 2022 68,268 2023 54,377 2024 47,608 2025 41,539 2026 and thereafter 346,741 Total lease payments 652,530 Amount representing interest 25,280 Total lease liabilities for operating leases 627,250

Variable interest entities and

Variable interest entities and securitizations	12 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Variable interest entities and securitizations	24. Variable interest entities and securitizations Variable interest entities In the normal course of business, the MHFG Group is involved with VIEs primarily through the following types of transactions: asset-backed commercial paper/loan programs, asset-backed securitizations, investments in securitization products, investment funds, trust arrangements, structured finance, and funding vehicles. The Group consolidates certain of these VIEs, where the Group is deemed to be the primary beneficiary because it has both (1) the power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and (2) the obligation to absorb losses or the right to receive benefits that could potentially be significant to the VIE. The MHFG Group reassesses whether it is the primary beneficiary on an ongoing basis as long as the Group has any continuing involvement with the VIE. There are also other VIEs, where the Group has determined that it is not the primary beneficiary but has significant variable interests. In evaluating the significance of the variable interests, the Group takes into consideration the extent of its involvement with each VIE, such as the seniority of its investments, the share of its holding in each tranche and the variability it expects to absorb, as well as other relevant facts and circumstances. The likelihood of loss is not necessarily relevant to the determination of significance, and therefore, “significant” does not imply that there is high likelihood of loss. The maximum exposure to loss that is discussed in this section refers to the maximum loss that the Group could possibly be required to record in its consolidated statements of income as a result of its involvement with the VIEs. This represents exposures associated with both on-balance-sheet off-balance-sheet The table below shows the consolidated assets of the Group’s consolidated VIEs as well as total assets and maximum exposure to loss for its significant unconsolidated VIEs, in which the Group has determined that its maximum exposure to loss is greater than specific thresholds or meets certain other criteria as of March 31, 2019 and 2020: Consolidated VIEs Significant unconsolidated VIEs 2019 Consolidated assets Total assets Maximum exposure to loss (in billions of yen) Asset-backed commercial paper/loan programs 2,249 — — Asset-backed securitizations 571 70 8 Investments in securitization products 372 — — Investment funds 2,836 1,280 410 Trust arrangements and other 20 — — Total 6,048 1,350 418 Consolidated VIEs Significant unconsolidated VIEs 2020 Consolidated assets Total assets Maximum exposure to loss (in billions of yen) Asset-backed commercial paper/loan programs 2,160 — — Asset-backed securitizations 572 77 7 Investments in securitization products 370 — — Investment funds 2,694 2,299 514 Trust arrangements and other 19 — — Total 5,815 2,376 521 As of March 31, 2019 and 2020, the noncontrolling interests in consolidated VIEs amounted to ¥621 billion and ¥541 billion, respectively, and included in the Group’s equity-classified noncontrolling interests. The Group has not provided financial or other support to consolidated or unconsolidated VIEs that the Group was not previously contractually required to provide. The tables below present the carrying amounts and classification of assets and liabilities on the MHFG Group’s balance sheets that relate to its variable interests in significant unconsolidated VIEs, as of March 31, 2019 and 2020: Assets on balance sheets related to unconsolidated VIEs: 2019 2020 (in billions of yen) Trading account assets 104 108 Investments 168 267 Loans 71 55 Total 343 430 Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs: 2019 2020 (in billions of yen) Payables under securities lending transactions 47 47 Trading account liabilities 1 2 Total 48 49 Maximum exposure to loss (Note) 418 521 Note: This represents the maximum amount the Group could possibly be required to record in its consolidated statements of income associated with on-balance-sheet off-balance-sheet In the table above the nature of the Group’s variable interest can take different forms, as described further in the notes below. Additionally the Group’s exposure to the obligations of VIEs is generally limited to its interest in these entities. In certain instances the Group provides undrawn commitments to the VIEs. The Group’s maximum exposure to loss presented in the table above does not include the benefit of offsetting financial instruments that are held to mitigate the risks associated with these variable interests. Furthermore, the Group’s maximum exposure to loss presented in the table above is not reduced by the amount of collateral held as part of the transaction with the VIE or any party to the VIE directly against a specific exposure to loss. Asset-backed commercial paper/loan programs The MHFG Group manages several asset-backed commercial paper/loan programs that provide its clients with off-balance-sheet Asset-backed securitizations The MHFG Group acts as an arranger of various types of structured finance schemes to meet its clients’ needs for off-balance-sheet financial asset by the client is structured to be bankruptcy remote by use of a bankruptcy remote entity, which is deemed to be a VIE because its equity holder does not have decision making rights. The MHFG Group receives fees for structuring and/or distributing the securities sold to investors. In some cases, the MHFG Group itself purchases the securities issued by the entities and/or provides loans to the VIEs. In addition, the MHFG Group establishes several single-issue and multi-issue special purpose entities that issue collateralized debt obligations (“CDO”) or CLO, synthetic CDO/CLO or other repackaged instruments to meet clients’ and investors’ financial needs. The MHFG Group also arranges securitization transactions including CMBS, RMBS and others. In these transactions, the MHFG Group acts as an underwriter, placement agent, asset manager, derivatives counterparty, and/or investor in debt and equity instruments. In these cases above, the MHFG Group consider that these variable interests are not significant as the MHFG Group does not have material balance sheet or off-balance The MHFG Group established certain VIEs to securitize its own mortgage loans. The Group provides servicing for and holds retained subordinated beneficial interests in the securitized mortgage loans. In addition, the Group retains credit exposure in the form of guarantees on these loans. In its role as a servicer, the Group has the power to direct the entity’s activities that most significantly impact the entity’s economic performance by managing defaulted mortgage loans. In addition, through its retained interests and its aforementioned involvement as a guarantor, the Group has the obligation to absorb losses and the right to receive benefits that could potentially be significant to the entity. Therefore, the Group consolidates such VIEs. The MHFG Group has started Tender Option Bond (“TOB”) programs in the fiscal year ended March 31, 2020, which is associated with trusts that hold highly-rated, fixed-rate and tax-exempt Non-Customer Non-Customer Non-Customer Investments in securitization products The MHFG Group invests in, among other things, various types of CDO/CLO, synthetic CDO/CLO and repackaged instruments, CMBS and RMBS arranged by third parties for the purpose of generating current income or capital appreciation, which all utilize entities that are deemed Investment funds The MHFG Group invests in various investment funds, including securities investment trusts, which collectively invest in equity and debt securities that include listed Japanese securities and investment grade bonds. Investment advisory companies or fund management companies, including the Group’s subsidiaries and affiliates, administer and make investment decisions about such investment funds. The Group considers that it is a “significant” variable interest when the Group’s investment share is greater than threshold. The Group consolidates certain investment funds where it is deemed to be the primary beneficiary. The Group determines whether it is the primary beneficiary by evaluating whether it has both (1) the power to make investment decisions about the investment funds and (2) the obligation to absorb losses or the right to receive benefits that could potentially be significant to the investment funds. The Group consolidates certain investment funds where it is deemed to be the primary beneficiary. Trust arrangements The MHFG Group offers a variety of asset management and administration services under trust arrangements including security investment trusts, pension trusts and trusts used in the securitization of assets originated by and transferred to third parties. The Group receives trust fees for providing services as an agent or fiduciary on behalf of beneficiaries. In these cases, the MHFG Group consider that these variable interests are not significant other than specific involvements such as followings; With respect to guaranteed principal money trust products, the MHFG Group assumes certain risks by providing guarantees for the repayment of principal as required by the trust agreements or relevant Japanese legislation. The MHFG Group manages entrusted funds primarily through the origination of high quality loans and other credit-related products, investing in investment grade marketable securities such as Japanese government bonds and placing cash with the MHFG Group’s subsidiary trust banks. The Group has the power to determine which assets will be held by the VIEs or to manage these assets. In addition, through the principal guarantee agreements, the Group has the obligation to absorb losses that could potentially be significant to the VIEs. Therefore, the Group consolidates such VIEs. However, the MHFG Group does not consolidate certain guaranteed principal money trusts, which invest all the entrusted funds in the MHFG Group itself, as the Group has determined that it has no variable interests. See Note 23 “Commitments and contingencies” for the balances of guaranteed trust principal that are not consolidated at March 31, 2019 and 2020. With respect to non-guaranteed non-guaranteed Special purpose entities created for structured finance The MHFG Group is involved in real estate, commercial aircraft and other vessel and machinery and equipment financing to VIEs and financing in securitized receivable As the Group typically only provides senior financing with credit enhanced by subordinated interests and may sometimes act as an interest rate swap counterparty, the Group has determined that it does not have the power to direct the activities of the VIEs that most significantly impact the VIEs’ economic performance, or it does not have “significant” variable interests. Therefore the Group does not consolidate such VIEs. Funding Vehicles The MHFG Group has established several wholly-owned off-shore Securitization The MHFG Group engages in securitization activities and securitizes mortgage loans, other loans, government and corporate securities and other types of financial assets in the normal course of business. In these securitization transactions, the Group records the transfer of a financial asset as a sale when all the accounting criteria for a sale under ASC For the fiscal years ended March 31, 2018, 2019 and 2020, the MHFG Group neither made significant transfers of financial assets nor recognized significant gains or losses in securitization transactions accounted for as sales. The Group did not retain significant interests in securitization transactions accounted for as sales as of March 31, 2019 and 2020. There are certain transactions where transfers of financial assets do not qualify for the aforementioned sales criteria and are accounted for as secured borrowings. These transferred assets continue to be carried on the consolidated balance sheets of the MHFG Group. Such assets are associated with securitization transactions and loan participation transactions, which amounted to ¥207 billion and ¥143 billion as of March 31, 2019, and ¥176 billion and ¥153 billion as of March 31, 2020, respectively. Liabilities associated with securitization and loan participation transactions are presented as Payables under securities lending transactions and Other short-term borrowings or Long-term debt, respectively, on the consolidated balance sheets.

Noninterest income

Noninterest income	12 Months Ended
	Mar. 31, 2020
Noninterest income	25. Noninterest income Details of Noninterest income for the fiscal years ended March 31, 2018, 2019 and 2020 are as follows: 2018 2019 2020 (in millions of yen) Fee and commission income: Securities-related business (1) 180,122 145,270 139,124 Deposits and lending business (2) 156,426 152,283 157,420 Remittance business (1) 110,054 110,382 112,275 Asset management business (1) 100,765 97,852 98,720 Trust related business (1) 121,808 124,843 129,298 Agency business (1) 37,397 36,466 31,879 Guarantee related business (3) 28,258 28,582 28,974 Fees for other customer services (1) 130,881 157,612 170,195 Total Fee and commission income 865,711 853,290 867,885 Foreign exchange gains (losses)—net (3) 91,793 93,577 44,345 Trading account gains (losses)—net (2) 236,982 328,841 745,692 Investment gains (losses)—net: Debt securities (3) 7,757 (3,842 ) 31,032 Equity securities (3) 289,400 (155,947 ) (557,391 ) Equity in earnings (losses) of equity method investees—net (3) 24,342 29,172 34,012 Gains on disposal of premises and equipment (3) 8,225 5,145 2,583 Other noninterest income (2) (4) 80,453 72,135 139,582 Total 1,604,663 1,222,371 1,307,740 Notes: (1) These amounts are revenues from contracts within the scope of ASC 606, “Revenue from contracts with customers ” (“ASC 606”). (2) Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606. (3) These amounts are revenues from contracts that do not meet the scope of ASC 606. (4) These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 27 “Fair value” for further details. Certain Fee and commission income, Trading account gains (losses)—net and Other noninterest income outlined in the table above are considered to be revenues from contracts that are within the scope of ASC 606. The MHFG Group disaggregates Fee and commission income, which is the main part of revenues within the scope of ASC 606, by type of business or service in the table above. Fee and commission income For the MHFG Group’s accounting policy for the recognition of Fee and commission income, see Note 1 “Basis of presentation and summary of significant accounting policies.” Deposits and lending business fees consist of deposit-related fees and lending-related fees. Deposit-related fees, which amounted to ¥14 billion for the fiscal year ended March 31, 2020, are within the scope of ASC Trust related business fees consist of trust fees earned primarily through fiduciary asset management and administrative service and other trust-related fees, which amounted to ¥51 billion and ¥74 billion for the fiscal year ended March 31, 2019, respectively, and ¥54 billion and ¥75 billion for the fiscal year ended March 31, 2020, respectively. Trading account gains (losses)—net and Other noninterest income In addition to Fee and commission income, Trading account gains (losses)—net and Other noninterest income include certain revenues within the scope of ASC 606. Underwriting fees from trading securities, which amounted to ¥68 billion and ¥60 billion for the fiscal years ended March 31, 2019 and 2020, respectively, are within the scope of ASC 606 and accounted for in Trading account gains (losses)—net. Underwriting fees are primarily recognized at the point in time and all considerations of the transaction are fixed on trade date or pricing date . For the fiscal years ended March 31, 2019 and 2020, approximately ¥26 billion and ¥24 billion, respectively, of Other noninterest income were within the scope of ASC 606. Credit card interchange fees are within the scope of ASC 606 and accounted for in Other noninterest income. Credit card interchange fees are earned on credit card transactions conducted through payment networks and recognized upon settlement of the credit card payment transactions. Contract balances relating to revenues from contracts with customers subject to ASC 606 Contract assets and receivables from contracts with customers subject to ASC 606 are recognized in Accrued income or accounts receivable of Other assets. As of March 31, 2019 and 2020, the balance of contract assets was not material. Contract liabilities are recognized in unearned income of Other liabilities. As of March 31, 2019 and 2020, the balance of contract liabilities was not material. Remaining performance obligations relating to revenues from contracts with customers subject to ASC 606 Remaining performance obligations are services that the MHFG Group has committed to provide in the future in connection with its contracts with customers. As of March 31, 2019 and 2020, the amount of expected revenues from current obligations to provide services in the future is not material. It excludes revenues from contracts less than one year or contracts that have provisions that allow the Group to recognize revenue at the amount it has the right to invoice.

Trading account gains and losse

Trading account gains and losses	12 Months Ended
	Mar. 31, 2020
Trading Account Gains And Losses [Abstract]
Trading account gains and losses	26. Trading account gains and losses The MHFG Group performs trading activities through market making, sales, and arbitrage. Accordingly, Trading account gains (losses)—net include gains and losses from transactions undertaken for trading purposes, including both market making for customers and proprietary trading, or transactions through which the Group seeks to capture gains arising from short-term changes in market value. Trading account gains (losses)—net also include gains and losses related to changes in the fair value of derivatives and other financial instruments not eligible for hedge accounting under U.S. GAAP that are utilized to offset mainly interest rate risk related to the Group’s various assets and liabilities, as well as gains and losses related to changes in the fair value of foreign currency-denominated debt securities reported as Trading securities. Net trading gains (losses) for the fiscal years ended March 31, 2018, 2019 and 2020 are comprised of the following: 2018 2019 2020 (in millions of yen) Trading account gains (losses)—net: Trading securities 333,749 158,162 267,514 Derivative contracts: Interest rate contracts (63,260 ) 127,242 388,289 Foreign exchange contracts (1) 61,046 6,748 (111,920 ) Equity-related contracts (2) (98,807 ) 37,875 217,744 Credit-related contracts (3) (2,076 ) 269 5,208 Other contracts 6,330 (1,455 ) (21,143 ) Total 236,982 328,841 745,692 Foreign exchange gains (losses)—net (4) 91,793 93,577 44,345 Net trading gains (losses) 328,775 422,418 790,037 Notes: (1) Amounts include gains and losses on currency swaps. (2) The net gains (losses) excluded from the assessment of the effectiveness of fair value hedges is included in the above table. (3) Amounts do not include the net gains (losses) of ¥(754) million, ¥(736) million and ¥2,838 million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2018, 2019 and 2020, respectively. The net gains (losses) is recorded in Other noninterest income (expenses). (4) Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.

Fair value

Fair value	12 Months Ended
	Mar. 31, 2020
Fair value	27. Fair value Fair value measurements ASC 820 defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820 also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. In addition, ASC 820 precludes (1) the deferral of gains and losses at inception of certain derivative contracts whose fair value was not evidenced by market-observable data, and (2) the use of block discounts when measuring the fair value of instruments traded in an active market, which Fair value hierarchy ASC 820 specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. The standard describes three levels of inputs that may be used to measure fair value: Level 1 Quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities include debt and equity securities and derivative contracts that are traded in an active exchange market. Level 2 Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 2 assets and liabilities include debt securities with quoted prices that are traded less frequently than exchange-traded instruments. If no quoted market prices are available, the fair values of debt securities and over-the-counter Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Level 3 assets and liabilities include financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. Valuation process The MHFG Group has established valuation policies which govern the principles of fair value measurements and the authority and duty of each department. The Group has also established procedure manuals which describe valuation techniques and related inputs for determining the fair values of various financial instruments. The policies require that the measurement of fair values be carried out in accordance with the procedures performed by the risk management departments or the back offices which are independent from the front offices. The policies also require the risk management departments to check and verify whether the valuation methodologies defined in the procedure manuals are fair and proper and the internal audit departments to periodically review the compliance with the procedures throughout the Group. Although the valuation methodologies and related inputs are consistently used from period to period, a change in the market environment sometimes leads to a change in the valuation methodologies and the inputs. For instance, a change in market liquidity due to a delisting or a new listing is one of the key drivers of revisions to the valuation methodologies and the inputs. The key drivers also include the availability or the lack of market observable inputs and the development of new valuation methodologies. Price verification performed through the Group’s internal valuation process has an important role in identifying whether the valuation methodologies and the inputs need to be changed. The internal valuation process over the prices broker-dealers provide, primarily for Japanese securitization products, is described in more detail below in Available-for-sale securities. valuation The following is a description of valuation methodologies and inputs used for assets and liabilities measured at fair value on a recurring basis, including the general classification of such instruments pursuant to the fair value hierarchy and the MHFG Group’s valuation techniques used to measure fair values. During the fiscal year ended March 31, 2020, there were no significant changes made to the Group’s valuation techniques and related inputs. Trading securities and trading securities sold, not yet purchased When quoted prices for identical securities are available in an active market, the Group uses the quoted prices to measure the fair values of securities and such securities are classified in Level 1 of the fair value hierarchy. Level 1 securities include highly liquid government bonds and equity securities. When quoted prices for identical securities are available, but not actively traded, such securities are classified in Level 2 of the fair value hierarchy. When no quoted market prices are available, the Group estimates fair values by using pricing models with inputs that are observable in the market and such securities are classified in Level 2 of the fair value hierarchy. Level 2 securities include Japanese local government bonds, corporate bonds, and commercial paper. When less liquid market conditions exist for securities, the quoted prices are stale or the prices from independent sources vary significantly, such securities are generally classified in Level 3 of the fair value hierarchy. The fair values of securitization products such as RMBS, CMBS, ABS, and CLO are determined primarily by using a discounted cash flow model. The key inputs used for the model include default rates, recovery rates, prepayment rates, and discount rates. In the event that certain key inputs are unobservable or cannot be corroborated by observable market data, these financial instruments are classified in Level 3. Hedge funds the Group invests in are primarily multi strategy funds that employ a fundamental bottom-up start-up Derivative financial instruments Exchange-traded derivatives are valued using quoted market prices and consequently are classified in Level 1 of the fair value hierarchy. However, the majority of derivatives entered into by the Group are executed over-the-counter exchange over-the-counter Group implemented funding valuation adjustments in the fourth quarter to reflect the impact of funding on uncollateralized over-the-counter over-the-counter market Available-for-sale The fair values of available-for-sale non-binding Equity securities Equity securities mainly consist of marketable equity securities. The fair values of the marketable equity securities are based upon quoted market prices for identical equity securities trading as securities in an active market. Equity securities also include investments in certain investment funds measured using the NAV per share practical expedient including private equity funds and real estates funds. These securities are determined primarily using the same procedures described under Trading securities and trading securities sold, not yet purchased Other investments Other investments consist of investments held by consolidated investment companies. These companies typically hold investments in marketable and non non-marketable such securities, the Group firstly considers recent market transactions of identical securities, if applicable. Thereafter, the Group uses commonly accepted valuation techniques such as earnings multiples based on comparable public securities. Non-marketable Long-term debt Fair value accounting is elected for certain long-term debt instruments with embedded derivatives. The fair values are determined using a discounted cash flow model that considers the embedded derivatives and the terms and payment structures of the notes. The fair values of the derivatives embedded in such notes are primarily derived by using the same procedures described in Derivative financial instruments Items measured at fair value on a recurring basis Assets and liabilities measured at fair value on a recurring basis at March 31, 2019 and 2020, including those for which the MHFG Group has elected the fair value option, are summarized below: 2019 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,829 33 — 1,862 Japanese local government bonds — 134 — 134 U.S. Treasury bonds and federal agency securities 1,069 138 — 1,207 Other foreign government bonds 2,417 553 — 2,970 Agency mortgage-backed securities — 1,041 — 1,041 Residential mortgage-backed securities — — 11 11 Certificates of deposit and commercial paper — 1,047 — 1,047 Corporate bonds and other (2) 36 1,806 1,044 2,886 Equity securities 1,297 — 28 1,325 Trading securities measured at net asset value (3) 631 Derivative financial instruments: Interest rate contracts 36 5,729 21 5,786 Foreign exchange contracts 9 1,927 23 1,959 Equity-related contracts 58 63 4 125 Credit-related contracts — 16 2 18 Other contracts 2 4 10 16 Available-for-sale Japanese government bonds 10,902 995 — 11,897 Japanese local government bonds — 210 — 210 U.S. Treasury bonds and federal agency securities 1,009 — — 1,009 Other foreign government bonds 456 886 — 1,342 Agency mortgage-backed securities — 544 — 544 Residential mortgage-backed securities — 61 40 101 Commercial mortgage-backed securities — — 500 500 Japanese corporate bonds and other debt securities — 1,629 120 1,749 Foreign corporate bonds and other debt securities — 678 103 781 Equity securities Equity securities with readily determinable fair values 3,633 135 — 3,768 Equity securities measured at net asset value (3) 53 Other investments — — 35 35 Total assets measured at fair value on a recurring basis 22,753 17,629 1,941 43,007 Liabilities: Trading securities sold, not yet purchased 2,380 199 1 2,580 Derivative financial instruments: Interest rate contracts 38 5,564 8 5,610 Foreign exchange contracts 11 1,746 1 1,758 Equity-related contracts 82 51 9 142 Credit-related contracts — 16 1 17 Other contracts 1 4 9 14 Long-term debt (4) — 1,778 655 2,433 Total liabilities measured at fair value on a recurring basis 2,512 9,358 684 12,554 2020 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,516 22 — 1,538 Japanese local government bonds — 170 — 170 U.S. Treasury bonds and federal agency securities 4,580 461 — 5,041 Other foreign government bonds 1,128 547 — 1,675 Agency mortgage-backed securities — 3,390 — 3,390 Residential mortgage-backed securities — — 10 10 Certificates of deposit and commercial paper — 1,036 — 1,036 Corporate bonds and other (2) 41 1,398 1,115 2,554 Equity securities 1,000 650 30 1,680 Trading securities measured at net asset value (3) 462 Derivative financial instruments: Interest rate contracts 153 7,070 9 7,232 Foreign exchange contracts 9 2,900 17 2,926 Equity-related contracts 169 125 16 310 Credit-related contracts — 22 8 30 Other contracts 3 11 24 38 Available-for-sale Japanese government bonds 11,950 653 — 12,603 Japanese local government bonds — 273 — 273 U.S. Treasury bonds and federal agency securities 935 — — 935 Other foreign government bonds 436 975 — 1,411 Agency mortgage-backed securities — 505 — 505 Residential mortgage-backed securities — 53 31 84 Commercial mortgage-backed securities — — 615 615 Japanese corporate bonds and other debt securities — 1,678 157 1,835 Foreign corporate bonds and other debt securities — 678 174 852 Equity securities Equity securities with readily determinable fair values 2,670 95 — 2,765 Equity securities measured at net asset value (3) 72 Other investments — — 39 39 Total assets measured at fair value on a recurring basis 24,590 22,712 2,245 50,081 Liabilities: Trading securities sold, not yet purchased 1,880 515 — 2,395 Derivative financial instruments: Interest rate contracts 163 6,611 14 6,788 Foreign exchange contracts 8 2,890 1 2,899 Equity-related contracts 186 47 33 266 Credit-related contracts — 19 10 29 Other contracts 6 10 23 39 Long-term debt (4) — 1,916 621 2,537 Total liabilities measured at fair value on a recurring basis 2,243 12,008 702 14,953 Notes: (1) Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option. (2) The amount includes CLO and convertible bonds, which are classified in Level 3 . (3) In accordance with ASC 820, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented for these classes of assets are intended to permit the reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position. The amounts of unfunded commitments related to these investments at March 31, 2019 and 2020 were ¥37 billion and ¥47 billion, respectively. (4) Amounts represent items for which the Group elected the fair value option or for which it applied the practicability exception. Items measured at fair value on a recurring basis using significant unobservable inputs (Level 3) The following table presents a reconciliation for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the fiscal years ended March 31, 2019 and 2020: 2019 April 1, 2018 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments March 31, 2019 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 12 — (2) — — — — — — (1 ) 11 — Corporate bonds and other 1,013 1 (2) — — — 762 (378 ) — (354 ) 1,044 8 Equity securities 23 1 (2) — — — 7 (3 ) — — 28 (1 ) Derivative financial instruments, net (1) Interest rate contracts 21 (11 ) (2) — — — — — — 3 13 (5 ) Foreign exchange contracts 12 15 (2) — — — — — — (5 ) 22 14 Equity-related contracts 4 (15 ) (2) — — — — — — 6 (5 ) 3 Credit-related contracts 1 (2 ) (2) — — — — — — 2 1 1 Other contracts — 1 (2) — — — — — — — 1 1 Available-for-sale Residential mortgage-backed securities 54 — (3) — (4) — — — — — (14 ) 40 — Commercial mortgage-backed securities 441 — (3) 1 (4) — — 144 (72 ) — (14 ) 500 — Japanese corporate bonds and other debt securities 163 37 (3) (33 ) (4) — — 29 (7 ) — (69 ) 120 19 Foreign corporate bonds and other debt securities 80 — (3) (1 ) (4) 61 (42 ) 27 — — (22 ) 103 — Other investments 38 5 (3) — — — 13 (6 ) — (15 ) 35 (2 ) Liabilities: Trading securities sold, not yet purchased 4 1 (2) — — — (35 ) 33 — — 1 — Long-term debt 561 (6 ) (5) 10 (4) 7 — — — 192 (101 ) 655 5 2020 April 1, 2019 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments March 31, 2020 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 11 — (2) — — — — — — (1 ) 10 — Corporate bonds and other 1,044 (52 ) (2) — — — 802 (297 ) — (382 ) 1,115 (52 ) Equity securities 28 (1 ) (2) — — — 6 (2 ) — (1 ) 30 (1 ) Derivative financial instruments, net (1) Interest rate contracts 13 (6 ) (2) — 1 — — — — (13 ) (5 ) (16 ) Foreign exchange contracts 22 (4 ) (2) — — — — — — (2 ) 16 (3 ) Equity-related contracts (5 ) (8 ) (2) — — — — — — (4 ) (17 ) (10 ) Credit-related contracts 1 (2 ) (2) — (1 ) (1 ) — — — 1 (2 ) (1 ) Other contracts 1 2 (2) — — — — — — (2 ) 1 1 Available-for-sale Residential mortgage-backed securities 40 — (3) — (4) — — 3 — — (12 ) 31 — Commercial mortgage-backed securities 500 — (3) 1 (4) — — 201 (77 ) — (10 ) 615 — Japanese corporate bonds and other debt securities 120 2 (3) — (4) — — 106 — — (71 ) 157 — Foreign corporate bonds and other debt securities 103 — (3) (11 ) (4) — — 94 — — (12 ) 174 — Other investments 35 3 (3) — — — 15 — — (14 ) 39 3 Liabilities: Trading securities sold, not yet purchased 1 — (2) — — — (18 ) 17 — — — — Long-term debt 655 53 (5) 17 (4) 77 (8 ) — — 312 (345 ) 621 79 Notes: (1) Total Level 3 derivative exposures have been netted on the table for presentation purposes only. (2) Gains (losses) in Earnings are reported in Trading account gains (losses)—net, Foreign exchange gains (losses)—net or Other noninterest income (expenses). (3) Gains (losses) in Earnings are reported in Investment gains (losses)—net. (4) Gains (losses) in OCI are reported in Other comprehensive income (loss). (5) Gains (losses) in Earnings are reported in Other noninterest income (expenses). (6) Amounts represent total gains or losses recognized in earnings during the period. These gains or losses were attributable to the change in fair value relating to assets and liabilities classified as Level 3 that were still held at March 31, 2019 and 2020. Transfers of assets or liabilities between levels of the fair value hierarchy are assumed to occur at the beginning of the period. During the fiscal year ended March 31, 2019, the transfers into Level 3 included ¥61 billion of Available-for-sale Available-for-sale Available-for-sale Available-for-sale During the fiscal year ended March 31, 2020, the transfers into Level 3 included ¥1 billion of net Derivative assets, ¥1 billion of net Derivative liabilities and billion of Long-term debt. Transfers into Level 3 for net Derivative assets and liabilities were primarily due to changes in the observability of the inputs used to measure fair value of certain interest rate derivatives and credit-related derivatives. Transfers into Level 3 for Long-term debt were primarily due to changes in the observability of the default rate ¥1 billion of net Derivative assets and ¥8 billion of Long-term debt. Transfers out of Level 3 for net Derivative assets were primarily due to changes in the observability of the inputs used to measure fair value of certain credit-related derivatives. Transfers out of Level 3 for Long-term debt were primarily due to changes in the observability of the default rate when valuing certain structured notes. Quantitative information about Level 3 fair value measurements The following table presents information about significant unobservable inputs related to the MHFG Group’s material classes of Level 3 assets and liabilities at March 31, 2019 and 2020: 2019 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Weighted average (5) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage-backed securities 51 Discounted cash flow Price-based Prepayment rate Default rate Recovery rate Discount margin 4%–19% 0%–1% 100%–100% 18bps–170bps 8% 0% 100% 51bps Commercial mortgage-backed securities 500 Discounted cash flow Price-based Discount margin 9bps–161bps 24bps Corporate bonds and other debt securities 1,267 Discounted cash flow Price-based Prepayment rate (1) Default rate (1) Recovery rate (1) Discount margin (1) Discount margin (2) 22%–22% 2%–2% 69%–69% 48bps–1,173bps 4bps–1,063bps 22% 2% 69% 134bps 295bps Derivative financial instruments, net: Interest rate contracts 13 Internal valuation model (3) IR – IR correlation Default rate (4) 23%–100% 0%–63% Foreign exchange contracts 22 Internal valuation model (3) FX – IR correlation FX – FX correlation Default rate (4) 9%–55% 63%–63% 0%–63% Equity-related contracts (5 ) Internal valuation model (3) Equity – IR correlation Equity correlation Equity volatility 25%–25% 40%–100% 5%–36% Credit-related contracts 1 Internal valuation model (3) Default rate Credit correlation 0%–5% 29%–100% Long-term debt 655 Internal valuation model (3) IR – IR correlation 23%–100% FX – IR correlation 9%–55% FX – FX correlation 63%–63% Equity – IR correlation 25%–25% Equity – FX correlation 55%–88% Equity correlation 12%–100% Equity volatility 5%–49% Default rate 0%–4% Credit correlation 20%–100% 2020 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Weighted average (5) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage- 41 Discounted cash flow Price-based Prepayment rate Default rate Recovery rate Discount margin 4%–16% 0%–1% 100%–100% 5bps–170bps 7% 0% 100% 52bps Commercial mortgage-backed securities 615 Discounted cash flow Price-based Discount margin 7bps–185bps 22bps Corporate bonds and other debt securities 1,446 Discounted cash flow Price-based Prepayment rate (1) Default rate (1) Recovery rate (1) Discount margin (1) Discount margin (2) 13%–21% 0%–2% 10%–70% 61bps–1,160bps 5bps–1,528bps 21% 2% 67% 256bps 58bps Derivative financial instruments, net: Interest rate contracts (5 ) Internal valuation model (3) IR – IR correlation Default rate (4) 23%–100% 0%–63% Foreign exchange contracts 16 Internal valuation model (3) FX – IR correlation FX – FX correlation Default rate (4) -37%–49% 56%–65% 0%–63% Equity-related contracts (17 ) Internal valuation model (3) Equity – IR correlation Equity correlation Equity volatility 25%–25% 0%–100% 13%–157% Credit-related contracts (2 ) Internal valuation model (3) Default rate Credit correlation 0%–15% 30%–100% Long-term debt 621 Internal valuation model (3) IR – IR correlation 23%–100% FX – IR correlation -37%–50% FX – FX correlation 56%–65% Equity – IR correlation 25%–25% Equity – FX correlation -33%–100% Equity correlation 0%–100% Equity volatility 15%–157% Default rate 0%–12% Credit correlation 15%–100% Notes: (1) These inputs are mainly used for determining the fair values of securitization products such as CDO, CLO and ABS, other than RMBS and CMBS. (2) This input is mainly used for determining the fair values of Japanese corporate bonds and foreign corporate bonds. (3) Internal valuation model includes discounted cash flow models and the Black-Scholes option pricing model. (4) This input represents the counterparty default rate derived from the MHFG Group’s own internal credit analyses. (5) Weighted averages are calculated by weighting each input by the relative fair value of the respective financial instruments. IR = Interest rate FX = Foreign exchange Sensitivities to unobservable inputs and interrelationships between unobservable inputs The following is a description of the sensitivities and interrelationships of the significant unobservable inputs used to measure the fair values of Level 3 assets and liabilities. (1) Prepayment rate The prepayment rate is the estimated rate at which voluntary unscheduled repayments of the principal of the underlying assets are expected to occur. The movement of the prepayment rate is generally negatively correlated with borrower delinquency. A change in prepayment rate would impact the valuation of the fair values of financial instruments either positively or negatively, depending on the structure of financial instruments. (2) Default rate The default rate is an estimate of the likelihood of not collecting contractual payments. An increase in the default rate would generally be accompanied by a decrease in the recovery rate and an increase in the discount margin. It would also generally impact the valuation of the fair values of financial instruments negatively. (3) Recovery rate The recovery rate is an estimate of the percentage of contractual payments that would be collected in the event of a default. An increase in recovery rate would generally be accompanied by a decrease in the default rate. It would also generally impact the valuation of the fair values of financial instruments positively. (4) Discount margin The discount margin is the portion of the interest rate over a benchmark market interest rate such as LIBOR or swap rates. It primarily consists of a risk premium component which is the amount of compensation that market participants require due to the uncertainty inherent in the financial instruments’ cash flows resulting from credit risk. An increase in discount margin would generally impact the valuation of the fair values of financial instruments negatively. (5) Correlation Correlation is the likelihood of the movement of one input relative to another based on an established relationship. The change in correlation would impact the valuation of derivatives either positively or negatively, depending on the nature of the underlying assets. (6) Volatility Volatility is a measure of the expected change in variables over a fixed period of time. Some financial instruments benefit from an increase in volatility and others benefit from a decrease in volatility. Generally, for a long position in an option, an increase in volatility would result in an increase in the fair values of financial instruments. Items measured at fair value on a nonrecurring basis Certain assets and liabilities are measured at fair value on a nonrecurring basis. These assets and liabilities primarily include items that are measured at the lower of cost or fair value, and items that were initially measured at cost and have been written down to fair value as a result of impairment. The following table shows the fair value hierarchy for these items as of March 31, 2019 and 2020: 2019 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 125 — 41 84 177 Loans held-for-sale 3 — 3 — 3 Equity securities (without readily determinable fair values) 1 — — 1 1 Other investments 98 98 — — 104 Premises and equipment—net 9 — 4 5 34 Intangible assets — — — — 1 Total assets measured at fair value on a nonrecurring basis 236 98 48 90 320 2020 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 90 — — 90 136 Loans held-for-sale 26 — 20 6 26 Equity securities (without readily determinable fair values) 2 — — 2 2 Premises and equipment—net 1 — 1 — 12 Other — — — — 3 Good ill — — — — 2 Total assets measured at fair value on a nonrecurring basis 119 — 21 98 181 Note: The fair values may not be current as of the dates indicated, but rather as of the date the fair value change occurred. Accordingly, the carrying values may not equal current fair value. Loans in the table above have been impaired and measured based upon the observable market price of the loan or the fair value of the underlying collateral. Loans held-for-sale Equity securities (without readily determinable fair values) in the table above consist of non-marketable non-marketable fair value as a result of impairment or (2) adjusted upward or downward to fair value as a result of transactions observed for the identical or similar securities of the same issuer. The fair values of the impaired non-marketable non-marketable Other investments in the table above include certain equity method investments which have been impaired and written down to fair value. The fair values of the impaired marketable equity method investments are determined by their quoted market prices. As the securities are traded on an active exchange market, they are classified as Level 1. Premises and equipment—net , Intangible assets and Other assets in the table above have been impaired and written down to fair value. Goodwill in the table above is due to the decline in the fair value Fair value option The MHFG Group elected the fair value option for certain eligible financial instruments described below. Foreign currency denominated debt securities The MHFG Group elected the fair value option for foreign currency denominated debt securities to mitigate the volatility in earnings due to the difference in the recognition of foreign exchange risk between foreign currency denominated debt securities and financial liabilities. Following the election of the fair value option, these debt securities are reported as trading securities in Trading account assets. On April 1, 2018, the Group adopted ASU No.2016-01. Certain hybrid financial instruments The MHFG Group issues structured notes as part of its client-driven activities. Structured notes are debt instruments that contain embedded derivatives. The Group elected the fair value option for certain structured notes to mitigate accounting mismatches and to achieve operational simplifications. In addition, the Group measures certain notes that contain embedded derivatives at fair value under the practicability exception. These notes continue to be reported in Long-term debt and interest on these notes continues to be reported in Interest expense on long-term debt based on the contractual rates. The differences between the aggregate fair value of these notes and the aggregate unpaid principal balance of such instruments were ¥21 billion and ¥112 billion at March 31, 2019 and 2020, respectively. The net unrealized gains (losses) resulting from changes in fair values of these notes recorded in Other noninterest income (expenses) were of ¥(17) billion and ¥56 billion for the fiscal years ended March 31, 2019 and 2020, respectively. The Group records changes in fair value on these notes attributable to the instrument-specific credit risk in AOCI in accordance with ASU No.2016-01, Fair value of financial instruments ASC 825 requires the disclosure of the estimated fair value of financial instruments. The fair value of financial instruments is the amount that would be exchanged between willing parties, other than in a forced sale or liquidation. Quoted market prices, if available, are best utilized as estimates of the fair values of financial instruments. However, since no quoted market prices are available for certain financial instruments, fair values for such financial instruments have been estimated based on management’s assumptions, discounted cash flow models or other valuation techniques. Such estimation methods are described in more detail below. These estimates could be significantly affected by different sets of assumptions. There are certain limitations to management’s best judgment in estimating fair values of financial instruments and inherent subjectivity involved in estimation methodologies and assumptions used to estimate The following is a description of the valuation methodologies used for estimating the fair value of financial assets and liabilities not carried at fair value on the MHFG Group’s consolidated balance sheets. Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions The carrying value of short-term financial assets, such as cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions approximates the fair value of these assets since they generally involve limited losses from credit risk or have short-term maturities with interest rates that approximate market rates. Investments The fair value of held-to-maturity available-for-sale non-marketable Loans Loans have been fair valued based on the type of loan, credit quality, prepayment assumptions and remaining maturity. The fair value of loans is determined based on discounted cash flows using interest rates approximating the MHFG Group’s current rates for similar loans. The fair value of collateral dependent impaired loans is determined based on the fair value of the underlying collateral. Other financial assets The carrying value of other financial assets, which primarily consist of accounts receivable from brokers, dealers, and customers for securities transactions, accrued income and collateral provided for derivative transactions, approximates the fair value of these assets since they generally involve limited losses from credit risk or have short-term maturities with interest rates that approximate market rates. The majority of other financial assets is classified as Level 2, and included in the table in Note 12 “Other assets and liabilities.” Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions The carrying value of short-term financial liabilities, such as noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions approximates the fair value of these liabilities since they generally have short-term maturities with interest rates that approximate market rates. Interest-bearing deposits The carrying value of demand deposits approximates the fair value since it represents the amount payable on demand at the balance sheet date. The fair value of time d

Offsetting of financial assets

Offsetting of financial assets and financial liabilities	12 Months Ended
	Mar. 31, 2020
Offsetting of financial assets and financial liabilities	28. Offsetting of financial assets and financial liabilities Derivatives The MHFG Group enters into master netting arrangements such as International Swaps and Derivatives Association, Inc. (“ISDA”) or similar agreements with counterparties to manage mainly credit risks associated with counterparty default. If the predetermined events including counterparty default occur, these enforceable master netting arrangements or similar agreements give the Group the right to offset derivative receivables and derivative payables and related financial collateral such as cash and securities with the same counterparty. Repurchase and resale agreements and securities lending and borrowing transactions Repurchase and resale agreements and securities lending and borrowing transactions are generally covered by industry standard master repurchase agreements and industry standard master securities lending agreements with netting terms to manage mainly credit risks associated with counterparty default. In the event of default by the counterparty, these agreements with netting terms provide the Group with the right to offset receivables and payables related to such transactions with the same counterparty, and to liquidate the collateral held. The following table provides information about the offsetting of financial assets and financial liabilities at March 31, 2019 and 2020. The table includes derivatives, repurchase and resale agreements, and securities lending and borrowing transactions that are subject to enforceable master netting arrangements or similar agreements irrespective of whether or not they are offset on the Group’s consolidated balance sheets. Amounts not offset on the balance sheet (3) Gross amounts recognized Gross amounts offset on the balance sheet Net amounts presented on the balance sheet (2) Financial instruments (4) Cash collateral Net amounts (in billions of yen) 2019 Assets (1) Derivatives 7,403 — 7,403 (5,903 ) (528 ) 972 Receivables under resale agreements 12,589 — 12,589 (12,579 ) — 10 Receivables under securities borrowing transactions 1,921 — 1,921 (1,894 ) — 27 Total 21,913 — 21,913 (20,376 ) (528 ) 1,009 Liabilities (1) Derivatives 6,978 — 6,978 (5,766 ) (769 ) 443 Payables under repurchase agreements 14,312 — 14,312 (14,309 ) — 3 Payables under securities lending transactions 932 — 932 (931 ) — 1 Total 22,222 — 22,222 (21,006 ) (769 ) 447 2020 Assets (1) Derivatives 9,819 — 9,819 (7,723 ) (629 ) 1,467 Receivables under resale agreements 17,347 — 17,347 (17,197 ) — 150 Receivables under securities borrowing transactions 1,753 — 1,753 (1,709 ) — 44 Total 28,919 — 28,919 (26,629 ) (629 ) 1,661 Liabilities (1) Derivatives 9,220 — 9,220 (7,519 ) (1,215 ) 486 Payables under repurchase agreements 17,542 — 17,542 (17,191 ) — 351 Payables under securities lending transactions 626 — 626 (623 ) — 3 Total 27,388 — 27,388 (25,333 ) (1,215 ) 840 Notes: (1) Amounts relating to master netting arrangements or similar agreements where the MHFG Group does not have the legal right of set-off over-the-counter OTC-cleared (2) Derivative assets and liabilities are recorded in Trading account assets and Trading account liabilities, respectively. (3) Amounts do not exceed the net amounts presented on the balance sheet and do not include the effect of overcollateralization, where it exists. (4) For derivatives, amounts include derivative assets or liabilities and securities collateral that are eligible for offsetting under enforceable master netting arrangements or similar agreements.

Repurchase agreements and secur

Repurchase agreements and securities lending transactions accounted for as secured borrowings	12 Months Ended
	Mar. 31, 2020
Repurchase agreements and securities lending transactions accounted for as secured borrowings	29. Repurchase agreements and securities lending transactions accounted for as secured borrowings The following table shows the gross amounts of liabilities associated with repurchase agreements and securities lending transactions, by remaining contractual maturity at March 31, 2019 and 2020: Overnight and continuous Up to 30 days 31-90 Greater than 90 days Total (in billions of yen) 2019 Repurchase agreements 2,596 8,537 2,403 1,104 14,640 Securities lending transactions 1,012 473 — 313 1,798 Total 3,608 9,010 2,403 1,417 16,438 2020 Repurchase agreements 6,357 5,467 4,867 1,280 17,971 Securities lending transactions 877 231 — 316 1,424 Total 7,234 5,698 4,867 1,596 19,395 The following table shows the gross amounts of liabilities associated with repurchase agreements and securities lending transactions, by class of underlying collateral at March 31, 2019 and 2020: Repurchase agreements Securities lending transactions (in billions of yen) 2019 Japanese government bonds and Japanese local government bonds 2,118 430 Foreign government bonds and foreign agency mortgage-backed securities 11,613 396 Commercial paper and corporate bonds 223 52 Equity securities 492 902 Other 194 18 Total (Note) 14,640 1,798 2020 Japanese government bonds and Japanese local government bonds 1,790 269 Foreign government bonds and foreign agency mortgage-backed securities 15,218 359 Commercial paper and corporate bonds 273 50 Equity securities 542 730 Other 148 16 Total (Note) 17,971 1,424 Note: Amounts exceeded the gross amounts recognized in Note 28 “Offsetting of financial assets and financial liabilities” by ¥1,194 billion and ¥1,227 billion, at March 31, 2019 and 2020, respectively, which excluded the amounts relating to master netting agreements or similar agreements where the MHFG Group did not have the legal right of set-off The MHFG Group is required to post securities as collateral with a fair value equal to or in excess of the principal amount of the cash borrowed under repurchase agreements. For securities lending transactions, the Group receives collateral in the form of cash. These contracts involve risks, including (1) the counterparty may fail to return the securities at maturity and (2) the fair value of the securities posted may decline below the amount of the Group’s obligation and therefore the counterparty may require additional amounts. The Group attempts to mitigate these risks by entering into transactions mainly with central counterparty clearing houses which revalue assets and perform margin maintenance

Related Party Transactions

Related Party Transactions	12 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Related Party Transactions	30. Related party transactions The banking subsidiaries of MHFG make loans to the MHFG Group’s directors, executive officers, and other related parties. At March 31, 2019 and 2020, the aggregate loans to the Group’s equity method investees amounted to ¥473 billion and ¥497 billion, respectively, and outstanding loans to MHFG Group’s directors, executive officers, and other related parties were not considered significant. There were no loans to related parties that were considered impaired. Summarized Financial Information of the MHFG Group’s Equity Method Investees Summarized financial information of the MHFG Group’s equity method investees as of March 31, 2019 and 2020, and for each of the three years ended March 31, 2020, is as follows: 2019 2020 (in billions of yen) L 7,954 7,268 Total assets 28,674 27,036 Deposits 10,167 8,665 Total liabilities 26,387 25,014 Total equity 2,287 2,022 Noncontrolling interests 615 11 2018 2019 2020 (in billions of yen) Total interest and dividend income 458 503 586 Total interest expense 153 165 198 Provision (credit) for loan losses 66 84 81 Net interest income after provision (credit) for loan losses 239 254 307 Income before income tax expense 149 229 196 Net income 132 201 150

Business segment information

Business segment information	12 Months Ended
	Mar. 31, 2020
Business segment information	31. Business segment information The MHFG Group consists of the following five in-house The services that each in-house Retail & Business Banking Company This company provides financial services for individual customers, small and medium-sized Corporate & Institutional Company This company provides financial services for large corporations, financial institutions and public corporations in Japan. Global Corporate Company This company provides financial services for Japanese overseas affiliated corporate customers and non-Japanese Global Markets Company This company invests in financial products with market risk, such as interest rate risk, equity risk, and credit risk. Asset Management Company This company develops financial products and provides financial services that match the asset management needs of its wide range of customers from individuals to institutional investors. The reportable segment information, set forth below, is derived from the internal management reporting systems used by management to measure the performance of the Group’s operating segments. Management measures the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. In addition, the format and information are presented primarily on the basis of Japanese GAAP. Therefore, they are not consistent with the consolidated financial statements prepared in accordance with U.S. GAAP. A reconciliation is provided for the total amount of all business segments’ “Net business profits (losses) + Net gains (losses) related to ETFs and others” with income before income tax expense under U.S. GAAP, and the total amount of all business segments’ “Fixed assets” with the total amount of Premises and equipment-net, MHFG (Consolidated) 2018 (5) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (4) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (1) 725.7 431.0 327.3 387.2 50.0 74.4 1,995.6 General and administrative (2) 724.3 208.4 239.6 204.7 27.6 39.6 1,444.2 Equity in earnings (losses) of equity method investees—net 12.7 1.0 2.3 — 2.9 2.6 21.5 Amortization of goodwill and others 0.4 0.4 0.4 2.3 8.0 2.4 13.9 Others — — — — — (21.0 ) (21.0 ) Net business profits (losses) (3) 13.7 223.2 89.6 180.2 17.3 14.0 538.0 MHFG (Consolidated) 2019 (5) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (4) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (1) 705.9 473.4 400.3 192.4 49.6 6.1 1,827.7 General and administrative (2) 713.5 205.7 237.9 207.5 27.3 48.7 1,440.6 Equity in earnings (losses) of equity method investees—net 18.1 0.9 7.2 — 1.3 23.7 51.2 Amortization of goodwill and others 0.4 0.4 0.4 2.3 8.0 2.1 13.6 Others — — — — — (16.3 ) (16.3 ) Net business profits (losses) (3) 10.1 268.2 169.2 (17.4 ) 15.6 (37.3 ) 408.4 Fixed assets (6) 499.3 225.8 176.9 92.6 0.1 662.5 1,657.2 MHFG (Consolidated) 2020 Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (4) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (1) 673.6 462.4 417.8 410.1 48.4 60.5 2,072.8 General and administrative expenses (2) 668.5 215.1 249.0 208.9 29.0 41.0 1,411.5 Equity in earnings (losses) of equity method investees—net 11.8 2.0 10.3 — 1.3 5.0 30.4 Amortization of goodwill and others 0.4 0.4 0.4 2.3 7.8 1.9 13.2 Others — — — — — (5.9 ) (5.9 ) Net business profits (losses) (3) 16.5 248.9 178.7 198.9 12.9 16.7 672.6 Fixed assets (6) 503.7 204.1 173.0 91.5 0.1 767.4 1,739.8 Notes: (1) “Gross profits + Net gains (losses) related to ETFs and others” is reported instead of sales reported by general corporations. Gross profits is defined as the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income. Net gains (losses) related to ETFs and others consist of net gains (losses) on ETFs held by MHBK and MHTB on their non-consolidated (2) “General and administrative expenses” excludes non-allocated (3) Net business profits (losses) is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (as defined above) less general and administrative expenses plus equity in earnings (losses) of equity method investees—net and others. Measurement of net business profits (losses) is required for regulatory reporting to the Financial Services Agency of Japan. (4) “Others” includes the following items: • profits and expenses pertaining to consolidated subsidiaries that are not subject to allocation; • consolidating adjustments, including eliminating internal transaction between each segment; • equity in earnings (losses) of equity method investees-net • profits and losses pertaining to derivative transactions that reflect the counterparty risk of the individual parties and other factors in determining fair market value. (5) Beginning on April 1, 2018, new allocation methods for income and expense transactions between each segment and “Others” have been applied. In connection with the use of the new allocation methods, the presentation of “Net business profits” has changed to “Net business profits (losses) + Net gains (losses) related to ETFs and others.” Before the change, “Net gains (losses) related to ETFs and others” were included in “Gross profits” of each segment and eliminated in “Others.” In addition, “Amortization of goodwill and others” has been presented as a new item. Figures for the fiscal year ended March 31, 2018 have been restated for the new allocation methods. These changes more appropriately reflect the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates. (6) “Fixed assets” is presented based on Japanese GAAP and corresponds to the total amount of the following U.S. GAAP accounts: Premises and equipment-net; Reconciliation As explained above, the measurement bases of the internal management reporting systems and the income and expenses items included are different from the accompanying consolidated statements of income. Therefore, it is impracticable to present reconciliations of all the business segment’s information, other than net business profits (losses), to the corresponding items in the accompanying consolidated statements of income. A reconciliation of “Net business profits (losses) + Net gains (losses) related to ETFs and others” for the fiscal years ended March 31, 2018, 2019 and 2020 presented above to income before income tax expense shown on the consolidated statements of income and a reconciliation of “Fixed assets” at March 31, 2019 and 2020 to the total amount of Premises and equipment-net, 2018 2019 2020 (in billions of yen) Net business profits (losses) + Net gains (losses) related to ETFs and others 538.0 408.4 672.6 Adjustment to reconcile management reporting to Japanese GAAP: General and administrative expenses: non-allocated (30.9 ) 23.3 46.3 Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans) (17.0 ) (30.7 ) (183.3 ) Gains on reversal of reserves for possible losses on loans, and others 173.3 11.2 11.6 Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others 191.9 259.9 126.6 Net extraordinary gains (losses) 17.5 (497.9 ) (19.2 ) Others (72.8 ) (57.9 ) (35.9 ) Income before income tax expense under Japanese GAAP 800.0 116.3 618.7 Adjustment to reconcile Japanese GAAP to U.S. GAAP: Derivative financial instruments and hedging activities (110.2 ) 45.3 111.2 Investments 98.1 (273.3 ) (480.9 ) Loans (2.4 ) (11.9 ) (3.0 ) Allowances for loan losses and off-balance-sheet 6.8 (5.8 ) 0.7 Premises and equipment 35.4 303.6 (96.1 ) Land revaluation 3.4 10.2 2.1 Business combinations 15.6 (12.8 ) 6.0 Pension liabilities (4.4 ) (32.2 ) (56.7 ) Consolidation of variable interest entities 2.7 (39.0 ) 39.3 Foreign currency translation 12.1 1.7 17.3 Others (17.8 ) (17.0 ) (5.1 ) Income before income tax expense under U.S. GAAP 839.3 85.1 153.5 2019 2020 (in billions of yen) Fixed assets 1,657.2 1,739.8 U.S. GAAP adjustments (Note) 413.1 887.2 Premises and equipment-net, 2,070.3 2,627.0 Note: The U.S. GAAP adjustments are primarily comprised of GAAP differences mainly from ROU assets related to operating leases not recognized under Japanese GAAP; internally developed software, which was impaired under Japanese GAAP; land, which was revalued under Japanese GAAP; and the consolidation of certain variable interest entities, which are not consolidated under Japanese GAAP. ROU assets are recognized on balance sheets in connection with the adoption of ASU No.2016-02

Foreign activities

Foreign activities	12 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Foreign activities	32. Foreign activities The following table presents consolidated income statement and total assets information by major geographic area. Foreign activities are defined as business transactions that involve customers residing outside of Japan. However, as the MHFG Group’s operations are highly integrated globally, estimates and assumptions have been made for an allocation among the geographic areas. Americas Japan United States of America Others Europe Asia/Oceania excluding Japan, and others Total (in billions of yen) Fiscal year ended March 31, 2018: Total revenue (1) 2,002.4 654.9 64.0 197.4 447.8 3,366.5 Total expenses (2) 1,582.5 478.8 38.5 172.6 254.8 2,527.2 Income before income tax expense 419.9 176.1 25.5 24.8 193.0 839.3 Net income 231.3 152.7 23.7 21.3 172.7 601.7 Total assets at end of fiscal year 142,587.8 28,135.9 4,380.4 11,677.8 17,473.7 204,255.6 Fiscal year ended March 31, 2019: Total revenue (1) 1,705.5 792.1 66.0 249.7 616.5 3,429.8 Total expenses (2) 2,082.6 696.5 46.1 203.2 316.3 3,344.7 Income (loss) before income tax expense (377.1 ) 95.6 19.9 46.5 300.2 85.1 Net income (loss) (331.4 ) 85.3 17.0 34.6 270.2 75.7 Total assets at end of fiscal year 133,443.5 25,913.5 4,824.7 15,322.5 18,107.0 197,611.2 Fiscal year ended March 31, 2020: Total revenue (1) 1,681.0 801.5 95.1 270.4 610.9 3,458.9 Total expenses (2) 2,008.9 679.2 41.5 239.1 336.7 3,305.4 Income (loss) before income tax expense (327.9 ) 122.3 53.6 31.3 274.2 153.5 Net income (loss) (312.8 ) 100.4 51.5 23.6 243.6 106.3 Total assets at end of fiscal year 137,470.4 34,650.4 4,137.3 15,487.0 19,473.7 211,218.8 Notes: (1) Total revenue is comprised of Interest and dividend income and Noninterest income. (2) Total expenses are comprised of Interest expense, Provision (credit) for loan losses and Noninterest expenses.

Mizuho Financial Group, Inc., p

Mizuho Financial Group, Inc., parent company	12 Months Ended
	Mar. 31, 2020
Condensed Financial Information Disclosure [Abstract]
Mizuho Financial Group, Inc., parent company	33. Mizuho Financial Group, Inc., parent company The following tables present the parent company only financial information of MHFG: Condensed balance sheets 2019 2020 (in millions of yen) Assets: Cash and due from banking subsidiaries 99,209 43,016 Interest-bearing deposits in banking subsidiaries 1,158 218 Investments in subsidiaries and affiliated companies: Banking subsidiaries 7,905,018 8,104,662 Non-banking subsidiaries and affiliated companies 1,412,369 1,139,694 Long-term loans receivable from a banking subsidiary 5,110,248 6,539,819 Other 351,951 471,225 Total 14,879,953 16,298,634 Liabilities and shareholders’ equity: Short-term borrowings from a banking subsidiary 945,505 860,000 Long-term debt 5,145,286 6,555,053 Other liabilities 62,643 371,216 Shareholders’ equity 8,726,519 8,512,365 Total 14,879,953 16,298,634 Condensed statements of income 2018 2019 2020 (in millions of yen) Income: Dividends from subsidiaries and affiliated companies: Banking subsidiaries 227,057 267,724 23,824 Non-banking 28,987 23,392 12,850 Management fees from subsidiaries 47,945 39,292 38,004 Interest income on loans and discounts 68,869 106,920 123,354 Gains on disposal of premises and equipment — — 10,866 Other income 52,672 9,575 7,088 Total 425,530 446,903 215,986 Expenses: Operating expenses 38,661 40,680 38,951 Interest expense 74,227 110,861 126,516 Other expense 28,123 59,049 25,313 Total 141,011 210,590 190,780 Equity in undistributed net income (loss) of subsidiaries 309,210 (173,142 ) 130,930 Income before income tax expense 593,729 63,171 156,136 Income tax expense (benefit) 16,121 (21,300 ) 5,941 Net income 577,608 84,471 150,195 Condensed statements of cash flows 2018 2019 2020 (in millions of yen) Cash flows from operating activities: Net income 577,608 84,471 150,195 Adjustments and other (302,109 ) 197,193 (92,059 ) Net cash provided by operating activities 275,499 281,664 58,136 Cash flows from investing activities: Proceeds from sales of Equity securities — 139,719 — Net change in loans (1,344,323 ) (1,075,059 ) (1,496,047 ) Purchases of premises and equipment (6,649 ) (11,640 ) (43,406 ) Proceeds from sales of premises and equipment — — 209,657 Net change in other investing activities (4,114 ) (1,310 ) (5,150 ) Net cash used in investing activities (1,355,086 ) (948,290 ) (1,334,946 ) Cash flows from financing activities: Net change in short-term borrowings (70,000 ) (140,000 ) (85,505 ) Proceeds from issuance of long-term debt 1,344,323 1,075,059 1,531,047 Repayment of long-term debt — — (35,000 ) Proceeds from issuance of common stock 3 3 — Purchases of treasury stock (1,611 ) (2,124 ) (1,441 ) Dividends paid (190,382 ) (190,413 ) (190,386 ) Net change in other financing activities 555 437 962 Net cash provided by financing activities 1,082,888 742,962 1,219,677 Effect of exchange rate changes on cash and cash equivalents — 540 — Net increase (decrease) in cash and cash equivalents 3,301 76,876 (57,133 ) Cash and cash equivalents at beginning of fiscal year 20,190 23,491 100,367 Cash and cash equivalents at end of fiscal year 23,491 100,367 43,234

Subsequent events

Subsequent events	12 Months Ended
	Mar. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	34. Subsequent events Share consolidation of MHFG’s common stock On June 25, 2020, a 1-for-10 share consolidation was approved at the Ordinary General Meeting of Shareholders. It will become effective on October 1, 2020 based on the shares owned by the shareholders recorded in the shareholder register as of September 30, 2020.

Basis of presentation and sum_2

Basis of presentation and summary of significant accounting policies (Policies)	12 Months Ended
	Mar. 31, 2020
Basis of presentation	Basis of presentation Mizuho Financial Group, Inc. (“MHFG”) is a joint stock corporation with limited liability under the laws of Japan. MHFG is a holding company for Mizuho Bank, Ltd. (“MHBK”), Mizuho Trust & Banking Co., Ltd. (“MHTB”), Mizuho Securities Co., Ltd. (“MHSC”), Asset Management One Co., Ltd. (“Asset Management One”), and other subsidiaries. MHFG, through its subsidiaries (“the MHFG Group,” or “the Group”), provides domestic and international financial services in Japan and other countries. For a discussion of the Group’s segment information, see Note 31 “Business segment information.” MHFG and its domestic subsidiaries as well as its foreign subsidiaries maintain their accounting records in accordance with the accounting standards of Japan and those standards of the countries in which they are domiciled. Certain adjustments and reclassifications have been incorporated in the accompanying consolidated financial statements to conform them to the accounting principles generally accepted in the United States of America (“U.S. GAAP”). The consolidated financial statements are stated in Japanese yen, the currency of the country in which MHFG is incorporated and principally operates. The accompanying consolidated financial statements include the accounts of MHFG and its subsidiaries. MHFG’s fiscal year ends on March 31. MHFG’s subsidiaries fiscal year end is determined by each subsidiary. If the fiscal year end of a subsidiary has more than three months discrepancy from the MHFG’s fiscal year end, the subsidiary executes provisional financial closing. For those subsidiaries where the fiscal year end is not on March 31 and where the subsidiaries do not execute provisional financial close, the effect on the MHFG Group’s consolidated financial statements of all material events through the date of each of the periods presented in the consolidated financial statements has been considered for adjustment and/or disclosure. When determining whether to consolidate investee entities, the MHFG Group performs an analysis of the facts and circumstances of the particular relationships between the MHFG Group and the investee entities as well as the ownership of voting shares. The consolidated financial statements also include the accounts of VIEs for which MHFG or its subsidiaries have been determined to be the primary beneficiary in accordance with the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 810, “Consolidation” (“ASC 810”). All significant intercompany transactions and balances have been eliminated upon consolidation. The MHFG Group accounts for investments in entities over which it has significant influence by using the equity method of accounting. These investments are included in Other investments and the Group’s proportionate share of income or loss is included in Equity in earnings (losses) of equity method investees—net. Certain comparative amounts for the prior period have been reclassified in order to conform to the current period’s presentation.
Use of estimates	Use of estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect reported amounts and related disclosures. Specific areas, among others, requiring the application of management’s estimates and judgment include assumptions pertaining to the allowance for loan losses, allowance for losses on off-balance-sheet .
Definition of cash and cash equivalents	Definition of cash and cash equivalents For purposes of the consolidated statements of cash flows, Cash and cash equivalents consists of Cash and due from banks and Interest-bearing deposits in other banks. Cash deposited with central banks that must be maintained to meet minimum regulatory requirements is classified as restricted cash and included in Cash and cash equivalents. See Note 8 “Pledged assets and collateral” for more information on restricted cash.
Translation of foreign currency financial statements and foreign currency transactions	Translation of foreign currency financial statements and foreign currency transactions Financial statements of overseas entities are prepared using the functional currency of each entity and translated into Japanese yen for consolidation purposes. Assets and liabilities are translated using the fiscal-year-end Foreign currency translation gains and losses related to the financial statements of overseas entities of the MHFG Group, net of related income tax effects, are credited or charged directly to Foreign currency translation adjustments, a component of Accumulated other comprehensive income (loss), net of tax (“AOCI”). The tax effects of gains and losses related to the foreign currency translation of financial statements of overseas entities are not recognized unless it is apparent that the temporary differences will reverse in the foreseeable future. Assets and liabilities of domestic and overseas entities denominated in foreign currencies are remeasured into the functional currency of the respective entity at the fiscal year-end
Call loans and call money	Call loans and call money Call loans and call money represent lending/borrowing, primarily through the Japanese short-term money market, to/from other financial institutions such as banks, insurance companies, and securities brokerage houses.
Repurchase and resale agreements, securities lending and borrowing and other secured financing transactions	Repurchase and resale agreements, securities lending and borrowing and other secured financing transactions Securities sold under agreements to repurchase (“repurchase agreements”), securities purchased under agreements to resell (“resale agreements”) and securities lending and borrowing transactions are accounted for as secured financing or lending transactions when control over the underlying securities is not deemed to be surrendered by the transferor. Otherwise, they are recorded as sales of securities with related forward repurchase commitments or purchases of securities with related forward resale commitments in accordance with ASC 860, “Transfers and Servicing” (“ASC 860”). Under resale agreements, securities borrowing and certain derivatives transactions, the MHFG Group receives collateral in the form of securities. In many cases, the MHFG Group is permitted to sell or repledge the securities obtained as collateral. Disclosures in respect of such collateral are presented in Note 8 “Pledged assets and collateral.” With respect to repurchase agreements, securities lending, and certain derivative transactions, counterparties may have the right to sell or repledge securities that the MHFG Group has pledged as collateral. The MHFG Group separately discloses these pledged securities in the consolidated balance sheets. The MHFG Group monitors credit exposure arising from resale agreements, repurchase agreements, securities borrowing and securities lending transactions on a regular basis, and additional collateral is obtained from or returned to counterparties, as appropriate.
Trading securities and trading securities sold, not yet purchased	Trading securities and trading securities sold, not yet purchased Trading securities consist of securities and money market instruments that are bought and held principally for the purpose of reselling in the near term with the objective of generating profits on short-term fluctuations in price. Trading securities sold, not yet purchased, are securities and money market instruments sold to third parties that the MHFG Group does not own and is obligated to purchase at a later date to cover the short position. Trading securities and trading securities sold, not yet purchased, are recorded on the trade date. Trading securities and trading securities sold, not yet purchased, are recorded at fair value in the consolidated balance sheets in Trading account assets and Trading account liabilities with realized and unrealized gains and losses recorded on a trade date basis in Trading account gains (losses)—net in the consolidated statements of income. Interest and dividends on trading securities, including securities sold, not yet purchased, are recorded in Interest and dividend income or Interest expense on an accrual basis.
Investments	Investments Debt securities that the MHFG Group has both the positive intent and ability to hold to maturity are classified as Held-to-maturity Available-for-sale The credit component of an other-than-temporary impairment of a debt security is reported in Investment gains (losses)—net, and the noncredit component is reported in Other comprehensive income (loss). See Note 3 “Investments” for further discussion of impairment. Interest and dividends, as well as amortization of premiums and accretion of discounts, are reported in Interest and dividend income. Amortization of premiums and accretion of discounts on debt securities are recognized over their remaining maturities under the interest method. Gains and losses on disposition of investments are computed using the first-in first-out Other investments include marketable and non-marketable non-marketable
Derivative financial instruments	Derivative financial instruments Derivative financial instruments are bought and held principally for the purpose of market making for customers, proprietary trading in order to generate trading revenues and fee income, and also to manage the MHFG Group’s exposure to interest rate, credit and market risks related to asset and liability management. Such derivative financial instruments include interest rate, foreign currency, equity, commodity and credit default swap agreements, options, caps and floors, and financial futures and forward contracts. Derivatives bought and held for trading purposes are recorded in the consolidated balance sheets at fair value in Trading account assets and Trading account liabilities. The fair values of derivatives in a gain position and a loss position are reported as Trading account assets and Trading account liabilities, respectively. Derivatives used for asset and liability management include contracts that qualify for hedge accounting under ASC 815, “Derivatives and Hedging” (“ASC 815”). To be eligible for hedge accounting, derivative instruments must be highly effective in achieving offsetting changes in fair values or variable cash flows of the hedged items attributable to the particular risk being hedged. All qualifying hedging derivatives are valued at fair value and included in Trading account assets or Trading account liabilities. Derivatives that do not qualify for hedge accounting under ASC 815 are treated as trading positions and are accounted for as such. The fair value amounts recognized for all derivatives are presented on a gross basis and not offset against the amounts recognized for the right to reclaim cash collateral or the obligation to return cash collateral under the master netting agreement with the same counterparty. The fair values of derivative financial instruments are determined based on quoted market prices or broker-dealer quotes, if available. If not available, the fair values are estimated using quoted market prices for similar instruments, option or binomial pricing models or a present value cash flow analysis, utilizing current observable market information, where available. In determining the fair values, the Group considers various factors such as exchange or over-the-counter Changes in the fair values of all derivatives are recorded in earnings, except for derivatives qualifying as net investment hedges under ASC 815 which are recorded in AOCI. The changes in the fair values of all derivatives relating to foreign currency exchange rates are included in Foreign exchange gains (losses)—net and Trading account gains (losses)—net. Other elements of the changes in the fair values, including interest rate, equity and credit related components, except these of certain credit derivatives hedging the credit risk in the corporate loan portfolio, are recognized in Trading account gains (losses)—net. The net gain (loss) resulting from changes in the fair values of certain credit derivatives where the Group purchases protection to mitigate its credit risk exposure related to its corporate loan portfolio is recorded in Other noninterest income (expenses). Certain financial and hybrid instruments often contain embedded derivative instruments that possess implicit or explicit contract terms similar to those of a derivative instrument. Such derivative instruments are required to be fair-valued separately from the host contracts if they meet the bifurcation criteria of an embedded derivative. Such criteria include that the entire instrument is not marked to market through earnings, the economic characteristics and risks of the embedded contract terms are not clearly and closely related to those of the host contract and the embedded contract terms would meet the definition of a derivative on a stand-alone basis.
Loans	Loans Loans are generally carried at the principal amount adjusted for unearned income and deferred net nonrefundable loan fees and costs. Loan origination fees, net of certain direct origination costs, are deferred and recognized over the contractual life of the loan as an adjustment of yield using a method that approximates the interest method. Interest income on performing loans is accrued and credited to income as it is earned. Unearned income and discounts or premiums on purchased loans are deferred and recognized over the life of the loan using a method that approximates the interest method. Loans are considered impaired when, based on current information and events, it is probable that the MHFG Group will be unable to collect all the scheduled payments of principal and interest when due according to the contractual terms of the loans. Factors considered by management in determining if a loan is impaired include delinquency status and the ability of the debtor to make payments of the principal and interest when due. Impaired loans include loans past due for 90 days or more and restructured loans that meet the definition of a troubled debt restructuring (“TDR”) in accordance with ASC 310, “Receivables” (“ASC 310”). The majority of impaired loans have no contractual delinquency due to interest reductions and/or postponement of principal and interest. In March 2020 , approved accounting for certain TDRs. The temporary TDR relief is available to banks for loan modifications , All of the MHFG Group’s impaired loans are designated as nonaccrual loans and thus interest accruals and the amortization of net origination fees are suspended and capitalized interest is written off. Cash received on nonaccrual loans is accounted for as a reduction of the loan principal if the ultimate collectability of the principal amount is in doubt, otherwise, as interest income. Loans are not restored to accrual status until interest and principal payments are current and future payments are reasonably assured. Impaired loans are restored to non-impaired non-impaired Loans that have been identified for sale are classified as loans held for sale within Other assets and are accounted for at the lower of cost or fair value on an individual loan basis. If management decides to retain certain loans held for sale for the foreseeable future or until maturity or payoff, such items are transferred to Loans at the lower of cost or fair value.
Allowance and provision (credit) for loan losses	Allowance and provision (credit) for loan losses The MHFG Group maintains an appropriate allowance for loan losses to absorb probable losses inherent in the loan portfolio and makes adjustments to such allowance through Provision (credit) for loan losses in the consolidated statements of income. Loan principal that management judges to be uncollectible, based on detailed loan reviews and a credit quality assessment, is charged off against the allowance for loan losses. In general, the MHFG Group charges off loans when the Group determines that the obligor should be classified as substantially bankrupt or bankrupt. See Note 4 “Loans” for the definitions of obligor categories. Obligors in the retail portfolio segment are generally determined to be substantially bankrupt when they are past due for more than six months, and as for obligors in the corporate and other portfolio segments, the Group separately monitors the credit quality of each obligor without using time-based triggers. Subsequent recoveries of previously charged-off For the corporate portfolio segment, the credit quality review process and the credit rating process serve as the basis for determining the allowance for loan losses. Through such processes loans are categorized into groups to reflect the probability of default, whereby the MHFG Group’s management assesses the ability of borrowers to service their debt, taking into consideration current financial information, ability to generate cash, historical payment experience, analysis of relevant industry segments and current trends. For the retail portfolio segment, the different categories of past due status of loans are primarily utilized in the credit quality review and the credit rating processes as the basis for determining the allowance for loan losses. The other portfolio segment consists of loans of subsidiaries other than MHBK and MHTB, such as consolidated VIEs and overseas subsidiaries. MHFG Group’s accounting policies and the methodology used to estimate the allowance for loan losses for the other portfolio segment are equivalent to the policies and methodology used for the corporate portfolio segment. The allowance for loan losses is determined in accordance with ASC 310 and ASC 450, “Contingencies” (“ASC 450”). The MHFG Group measures the impairment of a loan when it is probable that the Group will be unable to collect all amounts due according to the contractual terms of the loan agreement, based on (1) the present value of expected future cash flows, after considering the restructuring effect and subsequent payment default with respect to TDRs, discounted at the loan’s initial effective interest rate, or (2) the loan’s observable market price, or (3) the fair value of the collateral if the loan is collateral dependent. The collateral that the Group obtains for loans consists primarily of real estate. In obtaining the collateral, the Group evaluates the fair value of the collateral and its legal enforceability. The Group also performs subsequent re-evaluations The formula allowance is applied to groups of loans that are collectively evaluated for impairment. The evaluation of the inherent loss in respect of these loans involves a high degree of uncertainty, subjectivity and judgment because probable loan losses are not easily identifiable or measurable. In determining the formula allowance, the MHFG Group therefore relies on a statistical analysis that incorporates loss rates based on its own historical loss experience and third-party data such as the number of corporate default cases which is updated once a year. In determining the allowance amount, the Group analyzes (1) the probability of default: (a) by using the most recently available data from April 2008 for the corporate portfolio segment, and the most recently available data for the past six years for the retail portfolio segment, in the case of normal obligors; and (b) by using the most recently available data from April 2002 for the corporate and retail portfolio segments, in the case of watch obligors; and (2) the loss given default by using the most recently available data for the past six years for the corporate and retail portfolio segments. As it pertains to TDR loans in the retail portfolio segment, which are subject to collective evaluation for impairment, the restructuring itself, as well as subsequent payment defaults, if any, are considered in determining obligor categories. The historical loss rate is adjusted, where appropriate, to reflect current factors, such as general economic and business conditions affecting the key lending areas of the MHFG Group, credit quality trends, specific industry conditions by portfolio segments, and recent loss experience in particular segments of the portfolio. When determining the length of the period to calculate the probability of default, the Group considers the uncertainty in the economic and business conditions. The estimation of the formula allowance is analyzed on a periodic basis by comparing the allowance with the actual results subsequent to the balance sheet date. Additionally, the allowance for loan losses is adjusted, where appropriate, to reflect significant uncertain economic and business conditions, such as COVID-19 pandemic. For March 31, 2020, the Group has incorporated the estimated impact of COVID-19 pandemic by adjusting its ASC 450 collective allowance; specifically by identifying impacted industries and obligors and adjusted its historical loss formula-based allowance for these loan groups, using assumptions such as anticipated business recovery period and current forecast for the growth rate of gross domestic product.
Allowance and provision (credit) for losses on off-balance-sheet instruments	Allowance and provision (credit) for losses on off-balance-sheet The MHFG Group maintains an allowance for losses on off-balance-sheet off-balance-sheet off-balance-sheet
Premises and equipment	Premises and equipment Premises and equipment are stated at historical cost, and depreciation and amortization are recorded over the estimated useful lives of the assets, except for leasehold improvements, which are amortized over the shorter of the estimated useful lives of the assets or the lease term. Depreciation and amortization are principally computed in accordance with the straight-line method with respect to buildings and leasehold improvements and in accordance with the declining-balance method with respect to other premises and equipment. The useful lives of premises and equipment are as follows: Years Buildings 3 to 50 Equipment and furniture 2 to 20 Regular repairs and maintenance costs that do not extend the estimated useful life of an asset are charged to expense as incurred. Upon sale or disposition of premises and equipment, the cost and related accumulated depreciation or amortization are removed from disposal
Impairment of long-lived assets	The MHFG Group’s long-lived assets that are held for use are reviewed periodically for events or changes in circumstances that indicate possible impairment. The Group’s impairment review is based on an undiscounted cash flow analysis of a group of assets, combined with associated liabilities, at the lowest level for which identifiable cash flows exist. Impairment occurs when the carrying value of the asset group exceeds the future undiscounted cash flows that the asset group is expected to generate. When impairment is identified, the future cash flows are then discounted to determine the estimated fair value of the asset group and an impairment charge is recorded for the difference between the carrying value and the estimated fair value of the asset group. The long-lived assets to be disposed of by sale are carried at the lower of the carrying amount or fair value, less estimated cost to sell.
Software	Software Internal and external costs incurred in connection with developing and obtaining software for internal use during the application development stage are capitalized. Such costs include salaries and benefits for employees directly involved with and who devote time to the project, to the extent such time is incurred directly on the internal use software project. The capitalization of software ceases when the software project has been substantially completed. The capitalized software is amortized on a straight-line basis over the estimated useful life, generally 5 to 10 years. Internal use software is reviewed for impairment whenever events or changes in circumstances indicate that its carrying amount may not be recoverable.
Goodwill	Goodwill Goodwill represents the excess of the total fair value of the acquired company, which consists of the consideration transferred, the fair value of any interest in the acquiree already held by the acquirer and the fair value of any noncontrolling interest in the acquiree over the fair value of net identifiable assets acquired at the date of acquisition in a business combination. The MHFG Group accounts for goodwill in accordance with ASC 350, “Intangibles—Goodwill and Other” (“ASC 350”). Goodwill is recorded at a designated reporting unit level for the purpose of assessing impairment. Goodwill is not amortized but is tested for impairment at least annually or more often if events or circumstances indicate there may be impairment. For both the annual and interim tests, the Group has the option to either (a) perform a quantitative impairment test or (b) first perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, in which case the Group would perform the quantitative test. An impairment loss is recorded to the extent the carrying amount of goodwill exceeds its estimated fair value. The estimated fair value of the reporting units is derived based on valuation techniques that the Group believes market participants would use for each of the reporting units. The price-to-book
Intangible assets	Group generally determines the estimated fair value by utilizing a discounted cash flow methodology or methodologies that incorporate price-to-book Intangible assets Intangible assets having definite useful lives are amortized over their estimated useful lives on either a straight-line basis or the method that reflects the pattern in which the economic benefits of the intangible assets are consumed. Intangible assets acquired in connection with the merger of MHSC and Shinko Securities Co., Ltd. (“Shinko”) and the integration of asset management functions of DIAM Co., Ltd. (“DIAM”), MHTB, Mizuho Asset Management Co., Ltd. (“MHAM”) and Shinko Asset Management Co., Ltd. (“Shinko Asset Management”) consist primarily of customer relationship intangibles, and are amortized over weighted-average amortization periods of 16 years and 16.9 years, respectively. Intangible assets having indefinite useful lives are not amortized and are subject to impairment tests. An impairment loss is recorded to the extent that the carrying amount of the indefinite-lived intangible asset exceeds its estimated fair value. For intangible assets subject to amortization, an impairment loss is recorded if the carrying amount is not recoverable and exceeds its estimated fair value.
Leases	Leases The MHFG Group, as a lessee, recognizes liabilities to make lease payments and right-of-use non-lease
Pension and other employee benefits	Pension and other employee benefits MHFG and certain subsidiaries sponsor pension plans which provide defined benefits to retired employees and other postretirement benefit plans, including severance indemnities. Severance indemnities are amounts payable to eligible employees upon termination of employment and are payable as a
Stock-based compensation	Stock-based compensation MHFG, MHBK, MHTB and MHSC have a position-based stock compensation program for Directors (“Stock Compensation I”) and a performance-based stock compensation program for Directors (“Stock Compensation II”). For both programs, the stock-based compensation cost is determined based on the fair value of MHFG’s common stock as of grant date. For Stock Compensation I and II, the liability related to the cash-based compensation cost is remeasured at each reporting date based on the fair value of MHFG’s common stock. For Stock Compensation II, the stock-based compensation costs are recognized evenly over the graded-vesting period, which is three years. For Stock Compensation I, as the program is effectively vested on the grant date, the stock-based compensation cost is recognized on the grant date. See Note 21 “Stock-based compensation” for further details of the stock options and the stock compensation programs.
Long-term debt	Long-term debt Premiums, discounts and issuance costs of long-term debt are amortized based on a method that approximates the interest method over the respective terms of the long-term debt.
Obligations under guarantees	Obligations under guarantees The MHFG Group provides customers with a variety of guarantees and similar arrangements, including standby letters of credit, financial and performance guarantees, credit protection, and liquidity facilities. The MHFG Group recognizes guarantee fee income over the guarantee period. The MHFG Group receives such a guarantee fee at the inception of the guarantee or in installments and, in either case, the present value of the total fees approximates the fair value of the guarantee.
Fair Value Measurements	Fair Value Measurements The MHFG Group carries certain of its financial assets and liabilities at fair value on a recurring basis. These financial assets and liabilities are primarily composed of trading account assets, trading account liabilities and available-for-sale non-recurring Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. In accordance with ASC 820, “Fair Value Measurement” (“ASC 820”), the Group classifies its financial assets and liabilities into the fair value hierarchy (Level 1, 2, and 3). See Note 27 “Fair value” for the detailed definition of each level. When determining fair value, the MHFG Group considers the principal or most advantageous market in which the Group would transact and considers assumptions that market participants would use when pricing the asset or liability. The Group maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. See Note 27 “Fair value” for descriptions of valuation methodologies used for its assets and liabilities by product.
Fee and commission income	Fee and commission income The MHFG Group recognizes revenue from contracts with customers in an amount that reflects the consideration to which the Group expects to be entitled in exchange for transferring control of a promised service. The timing of revenue recognition is dependent on whether the Group satisfies a performance obligation by transferring control of the service to a customer over time or at a point in time. Fee and commission income is presented exclusive of consumption taxes. The major components of fee and commission income are as follows. Securities-related business fees mainly consist of brokerage fees and commissions, and asset-based revenues. Brokerage fees and commissions mainly include fees earned from the execution of customer transactions and sales commissions of investment trusts. Brokerage fees and commissions are recognized at the point in time on transaction date. Asset-based revenues mainly include fees received from investment trust management companies in return for administration services, such as record keeping services, of investment trusts. The amounts of asset-based revenues are calculated based on customer’s net asset value and recognized over time in the period when the related service is provided. Deposit-related fees include service charges on consumer and commercial deposit accounts such as account transfer charges. Deposit-related fees are recognized at the point in time when the transactions occur or the related service is provided. Lending-related fees include fees for lending business such as commitment fees and arrangement fees. Remittance business fees include service charges for domestic and international funds transfers and collections. These fees are recognized at the point in time when the related service is provided. Asset management business fees consist of investment trust management fees and investment advisory fees for investment trusts. These fees are received from investment trusts in return for asset management services and/or investment advisory services on behalf of customers. The amounts of these fees are calculated based on a percentage of customer’s net asset value. These fees are recognized over time in the period when the management and/or advisory service is provided and the amount is fixed. Trust related business fees consist of trust fees earned primarily through fiduciary asset management and administrative service and other trust-related fees. Fees for fiduciary asset management and administration services for corporate pension plans and investment funds are recognized over time in the period when the related service is provided. Other trust-related fees mainly include brokerage commissions of real estate property, sales commissions of beneficial interest in real estate trust and charges for stock transfer agent services. These fees are mainly earned on a transaction basis and recognized at the point in time when the related service is provided. Agency business fees mainly include administration service fees related to the MHFG Group’s agency business such as Japan’s principal public lottery program and revenues from standing proxy services. These fees are recognized at the point in time when the related service is provided. Fees for other customer services include various revenues such as sales commissions of life insurance, service charges for electronic banking, financial advisory fees, and service charges for software development. Sales commissions from life insurance sales are received from insurance companies in return for selling insurance products and recognized when the insurance product is sold to customers. Service charges for electronic banking are mainly monthly basic usage fees and recognized over the related transaction period. Financial advisory fees are recognized over time in the period when the related advisory service based on the contract is rendered. Service charges for software development are recognized over time according to the progress of the development.
Fee and commission expenses	Fee and commission expenses The principal items included in fee and commission expenses are fee and commission
Income taxes	Deferred income tax benefit or expense is recognized for the changes in the net deferred tax asset or liability between periods.
Earnings per common share	Earnings per common share Basic earnings per common share are computed by dividing net income attributable to MHFG common shareholders by the weighted average number of common shares outstanding during the fiscal year. Diluted earnings per common share reflect all dilutive potential common shares such as stock options and the common shares of MHFG under the stock compensation programs. See Note 18 “Earnings per common share” for the computation of basic and diluted earnings per common share.

Basis of presentation and sum_3

Basis of presentation and summary of significant accounting policies (Tables)	12 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Useful Lives of Premises and Equipment	The useful lives of premises and equipment are as follows: Years Buildings 3 to 50 Equipment and furniture 2 to 20

Investments (Tables)

Investments (Tables)	12 Months Ended
	Mar. 31, 2020
Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale and Held-to-Maturity Securities	The amortized cost, gross unrealized gains and losses, and fair value of available-for-sale held-to-maturity Amortized cost Gross unrealized gains Gross unrealized losses Fair value (in millions of yen) 2019 Available-for-sale Debt securities: Japanese government bonds 11,888,510 11,259 2,998 11,896,771 Japanese local government bonds 208,308 1,671 87 209,892 U.S. Treasury bonds and federal agency securities 1,008,903 644 231 1,009,316 Other foreign government bonds 1,341,564 758 455 1,341,867 Agency mortgage-backed securities (1) 530,540 14,524 593 544,471 Residential mortgage-backed securities 99,904 1,420 191 101,133 Commercial mortgage-backed securities 495,313 4,914 104 500,123 Japanese corporate bonds and other debt securities 1,743,309 7,686 1,561 1,749,434 Foreign corporate bonds and other debt securities (2) 778,088 3,047 226 780,909 Total 18,094,439 45,923 6,446 18,133,916 Held-to-maturity Debt securities: Japanese government bonds 1,119,899 19,907 — 1,139,806 Agency mortgage-backed securities (3) 484,205 — 14,423 469,782 Total 1,604,104 19,907 14,423 1,609,588 Amortized cost Gross unrealized gains Gross unrealized losses Fair value (in millions of yen) 2020 Available-for-sale Debt securities: Japanese government bonds 12,651,677 1,319 50,224 12,602,772 Japanese local government bonds 272,412 649 494 272,567 U.S. Treasury bonds and federal agency securities 927,172 7,733 — 934,905 Other foreign government bonds 1,408,009 3,273 202 1,411,080 Agency mortgage-backed securities (1) 494,958 10,490 434 505,014 Residential mortgage-backed securities 83,077 1,405 151 84,331 Commercial mortgage-backed securities 609,559 5,551 106 615,004 Japanese corporate bonds and other debt securities 1,836,540 7,489 8,772 1,835,257 Foreign corporate bonds and other debt securities (2) 849,595 2,595 168 852,022 Total 19,132,999 40,504 60,551 19,112,952 Held-to-maturity Debt securities: Japanese government bonds 479,936 13,357 — 493,293 Agency mortgage-backed securities (3) 382,095 1,245 1,303 382,037 Total 862,031 14,602 1,303 875,330 Notes: (1) Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥517,330 million and ¥27,141 million, respectively, at March 31, 2019, and ¥504,953 million and ¥61 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government. (2) Other debt securities presented in this line primarily consist of Foreign negotiable certificates of deposit (“NCDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥246,503 million at March 31, 2019, and ¥271,387 million at March 31, 2020. (3) All Agency mortgage-backed securities presented in this line are Ginnie Mae securities.
Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities by Contractual Maturity	The amortized cost and fair value of available-for-sale held-to-maturity Amortized cost Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 5,872,058 4,980,539 1,753,300 45,780 12,651,677 Japanese local government bonds 11,530 171,825 84,528 4,529 272,412 U.S. Treasury bonds and federal agency securities 883,432 43,740 — — 927,172 Other foreign government bonds 1,029,641 378,368 — — 1,408,009 Agency mortgage-backed securities — — — 494,958 494,958 Residential mortgage-backed securities — — — 83,077 83,077 Commercial mortgage-backed securities 16,372 202,044 390,343 800 609,559 Japanese corporate bonds and other debt securities 98,532 868,704 545,320 323,984 1,836,540 Foreign corporate bonds and other debt securities 377,642 327,312 141,755 2,886 849,595 Total 8,289,207 6,972,532 2,915,246 956,014 19,132,999 Held-to-maturity Debt securities: Japanese government bonds — 479,936 — — 479,936 Agency mortgage-backed securities — — — 382,095 382,095 Total — 479,936 — 382,095 862,031 Fair value Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 5,872,485 4,963,282 1,722,090 44,915 12,602,772 Japanese local government bonds 11,537 172,052 84,443 4,535 272,567 U.S. Treasury bonds and federal agency securities 890,367 44,538 — — 934,905 Other foreign government bonds 1,031,189 379,891 — — 1,411,080 Agency mortgage-backed securities — — — 505,014 505,014 Residential mortgage-backed securities — — — 84,331 84,331 Commercial mortgage-backed securities 16,396 203,233 394,561 814 615,004 Japanese corporate bonds and other debt securities 98,589 868,675 544,559 323,434 1,835,257 Foreign corporate bonds and other debt securities 378,464 328,918 141,754 2,886 852,022 Total 8,299,027 6,960,589 2,887,407 965,929 19,112,952 Held-to-maturity Debt securities: Japanese government bonds — 493,293 — — 493,293 Agency mortgage-backed securities — — — 382,037 382,037 Total — 493,293 — 382,037 875,330
Gross Unrealized Losses and Fair Value of Available-for-Sale and Held-to-Maturity Securities, Aggregated by Length of Time that Individual Securities Have Been in a Continuous Unrealized Loss Position	The following table shows the gross unrealized losses and fair value of available-for-sale held-to-maturity Less than 12 months 12 months or more Total Fair value Gross unrealized losses Fair value Gross unrealized losses Fair value Gross unrealized losses (in millions of yen) 2019 Available-for-sale Debt securities: Japanese government bonds 2,296,536 1,441 1,332,688 1,557 3,629,224 2,998 Japanese local government bonds 9,752 32 38,873 55 48,625 87 U.S. Treasury bonds and federal agency securities 506,176 231 — — 506,176 231 Other foreign government bonds 438,771 321 26,782 134 465,553 455 Agency mortgage-backed securities (1) 466 2 37,706 591 38,172 593 Residential mortgage-backed securities — — 16,729 191 16,729 191 Commercial mortgage-backed securities 11,256 44 36,760 60 48,016 104 Japanese corporate bonds and other debt securities 417,825 924 440,937 637 858,762 1,561 Foreign corporate bonds and other debt securities 129,164 142 79,716 84 208,880 226 Total 3,809,946 3,137 2,010,191 3,309 5,820,137 6,446 Held-to-maturity Debt securities: Agency mortgage-backed securities (2) — — 469,782 14,423 469,782 14,423 Total — — 469,782 14,423 469,782 14,423 2020 Available-for-sale Debt securities: Japanese government bonds 10,339,320 43,204 283,561 7,020 10,622,881 50,224 Japanese local government bonds 162,665 418 34,114 76 196,779 494 U.S. Treasury bonds and federal agency securities — — — — — — Other foreign government bonds 196,990 202 — — 196,990 202 Agency mortgage-backed securities (1) 30,913 227 9,504 207 40,417 434 Residential mortgage-backed securities 9,524 62 5,450 89 14,974 151 Commercial mortgage-backed securities 15,115 85 7,478 21 22,593 106 Japanese corporate bonds and other debt securities 669,572 5,507 608,361 3,265 1,277,933 8,772 Foreign corporate bonds and other debt securities 152,058 165 5,564 3 157,622 168 Total 11,576,157 49,870 954,032 10,681 12,530,189 60,551 Held-to-maturity Debt securities: Agency mortgage-backed securities (2) — — 191,244 1,303 191,244 1,303 Total — — 191,244 1,303 191,244 1,303 Notes: (1) Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥11,107 million and ¥27,065 million, respectively, at March 31, 2019, and ¥40,417 million and ¥0 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government. (2) All Agency mortgage-backed securities presented in this line are Ginnie Mae securities.
Realized Gains and Losses on Sales of Available-for-Sale Securities	The following table shows the realized gains and losses on sales of available-for-sale 2018 2019 (Note) 2020 (Note) (in millions of yen) Gross realized gains 314,948 23,777 41,903 Gross realized losses (41,044 ) (26,299 ) (13,398 ) Net realized gains (losses) on sales of available-for-sale 273,904 (2,522 ) 28,505 Note: Effective April 1, 2018, the available-for-sale
Summary of Details of Net Gains and Losses on Equity Securities	The following table shows the details of the net gains and losses on Equity securities for the fiscal years ended March 31, 2019 and 2020: 2019 2020 (in millions of yen) Net gains (losses) recognized during the period on equity securities (155,947 ) (557,391 ) Less: Net gains (losses) recognized during the period on equity securities sold during the period 34,034 1,710 Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting period (189,981 ) (559,101 )
Summary of Downward Adjustments and Impairments and Upward Adjustments	The following table shows carrying amounts of equity securities without readily determinable fair values, for which the measurement alternative is used, and cumulative amounts due to downward adjustments and impairments and upward adjustments, at March 31, 2019 and 2020: 2019 2020 (in millions of yen) Carrying amounts at the end of the period 212,270 419,775 Downward adjustments and impairments 1,413 2,435 Upward adjustments 2,373 9,128
Summary of Composition of Other Investments	The following table summarizes the composition of Other investments at March 31, 2019 and 2020: 2019 2020 (in millions of yen) Equity method investments 354,268 404,513 Investments held by consolidated investment companies 35,472 39,438 Total 389,740 443,951
Summary of Equity Securities Without Readily Determinable Fair Values	The following table shows amounts recognized in earnings during the period due to downward adjustments and impairments and upward adjustments for equity securities without readily determinable fair values. 2019 2020 (in millions of yen) Downward adjustments and impairments 1,413 1,272 Upward adjustments 2,373 6,928

Loans (Tables)

Loans (Tables)	12 Months Ended
	Mar. 31, 2020
Loans Outstanding by Domicile and Industry of Borrower	The table below presents loans outstanding by domicile and industry of borrower at March 31, 2019 and 2020: 2019 2020 (in millions of yen) Domestic: Manufacturing 9,553,854 9,731,028 Construction and real estate 8,950,577 9,603,433 Services 5,016,971 5,992,511 Wholesale and retail 5,159,356 5,219,727 Transportation and communications 3,693,491 3,832,884 Banks and other financial institutions 4,345,589 4,634,442 Government and public institutions 2,358,904 2,198,805 Other industries (Note) 5,472,597 5,389,347 Individuals: Mortgage loans 8,950,216 8,567,099 Other 907,589 861,235 Total domestic 54,409,144 56,030,511 Foreign: Commercial and industrial 19,126,182 20,818,709 Banks and other financial institutions 9,086,721 10,475,277 Government and public institutions 296,872 317,284 Other 33,171 35,388 Total foreign 28,542,946 31,646,658 Total 82,952,090 87,677,169 Less: Unearned income and deferred loan fees—net 152,147 149,081 Total loans before allowance for loan losses 82,799,943 87,528,088 Note: Other industries of d
Credit Quality Information of Loans Based on MHFG Group's Internal Rating System	The table below presents credit quality information of loans based on the MHFG Group’s internal rating system at March 31, 2019 and 2020: Normal obligors Watch obligors excluding special attention obligors (1) Impaired loans Total Corporate Retail (2) Other (3) Corporate Retail (2) Other (3) (in millions of yen) 2019 Domestic: Manufacturing 9,205,542 69,080 19,805 141,202 8,278 1,303 108,644 9,553,854 Construction and real estate 8,182,062 505,142 15,920 186,753 14,490 25 46,185 8,950,577 Services 4,665,709 165,643 3,281 90,178 18,586 1 73,573 5,016,971 Wholesale and retail 4,682,630 161,392 26,881 127,695 25,553 591 134,614 5,159,356 Transportation and communications 3,543,952 71,934 934 37,993 7,472 — 31,206 3,693,491 Banks and other financial institutions 4,304,483 1,534 72 28,881 319 — 10,300 4,345,589 Government and public institutions 2,358,899 5 — — — — — 2,358,904 Other industries (4) 3,126,217 2,450 2,323,197 7,725 421 3,633 8,954 5,472,597 Individuals 233,986 9,384,955 64,974 21,127 70,427 1,168 81,168 9,857,805 Total domestic 40,303,480 10,362,135 2,455,064 641,554 145,546 6,721 494,644 54,409,144 Foreign: Commercial and industrial 16,101,326 182 2,488,800 347,060 — 38,404 150,410 19,126,182 Banks and other financial institutions 8,583,432 — 492,831 10,458 — — — 9,086,721 Government and public institutions 296,870 — — — — — 2 296,872 Other 1,480 9,713 19,690 333 — 879 1,076 33,171 Total foreign 24,983,108 9,895 3,001,321 357,851 — 39,283 151,488 28,542,946 Total 65,286,588 10,372,030 5,456,385 999,405 145,546 46,004 646,132 82,952,090 2020 Domestic: Manufacturing 9,007,095 62,921 17,445 475,983 7,474 684 159,426 9,731,028 Construction and real estate 8,849,784 473,339 12,710 201,384 10,928 — 55,288 9,603,433 Services 5,600,528 159,657 2,943 131,783 16,602 15 80,983 5,992,511 Wholesale and retail 4,766,460 145,568 17,156 119,778 22,363 873 147,529 5,219,727 Transportation and communications 3,692,025 65,535 395 44,250 7,664 303 22,712 3,832,884 Banks and other financial institutions 4,595,441 1,593 347 24,686 429 — 11,946 4,634,442 Government and public institutions 2,198,796 9 — — — — — 2,198,805 Other industries (4) 3,106,282 2,684 2,230,748 15,238 372 15,038 18,985 5,389,347 Individuals 208,832 8,989,113 63,185 20,990 60,128 2,279 83,807 9,428,334 Total domestic 42,025,243 9,900,419 2,344,929 1,034,092 125,960 19,192 580,676 56,030,511 Foreign: Commercial and industrial 17,806,263 284 2,526,317 314,273 — 36,593 134,979 20,818,709 Banks and other financial institutions 9,745,247 — 726,823 3,207 — — — 10,475,277 Government and public institutions 303,393 — 13,129 762 — — — 317,284 Other 1,333 10,406 20,558 1,684 15 843 549 35,388 Total foreign (5) 27,856,236 10,690 3,286,827 319,926 15 37,436 135,528 31,646,658 Total 69,881,479 9,911,109 5,631,756 1,354,018 125,975 56,628 716,204 87,677,169 Notes: (1) Special attention obligors are watch obligors with debt in TDR or 90 days or more delinquent debt. Loans to such obligors are considered impaired. (2) The primary component of the retail portfolio segment is mortgage loans to individuals which obligor category is classified based on past due status. The trigger to reclassify obligors from normal obligors to watch obligors excluding special attention obligors is when the past due status is more than 30 days. (3) Non-impaired (4) Other industries of domestic includes trade receivables and lease receivables of consolidated VIEs. (5) Impaired loans to foreign borrowers decreased by ¥15,960 million due mainly to the sale of certain loans, partly offset by deterioration of credit status of certain other borrowers.
Impaired Loans Information	The table below presents impaired loans information at March 31, 2019 and 2020: Recorded investment (1) Unpaid principal balance Related allowance (3) Average recorded investment Interest income recognized (4) Requiring an allowance for loan losses Not requiring an allowance for loan losses (2) Total (in millions of yen) 2019 Domestic: Manufacturing 103,039 5,605 108,644 111,533 39,301 122,764 1,404 Construction and real estate 36,873 9,312 46,185 51,158 4,661 42,224 487 Services 64,021 9,552 73,573 79,736 16,311 67,679 1,058 Wholesale and retail 124,911 9,703 134,614 147,665 38,763 130,860 1,814 Transportation and communications 28,297 2,909 31,206 32,139 13,146 29,864 412 Banks and other financial institutions 6,473 3,827 10,300 10,300 1,327 10,671 109 Other industries 8,867 87 8,954 9,149 5,761 6,042 29 Individuals 37,488 43,680 81,168 88,331 2,630 86,082 1,326 Total domestic 409,969 84,675 494,644 530,011 121,900 496,186 6,639 Foreign: Total foreign (5) 119,079 32,409 151,488 164,984 47,345 113,559 1,518 Total 529,048 117,084 646,132 694,995 169,245 609,745 8,157 2020 Domestic: Manufacturing 152,865 6,561 159,426 162,742 62,879 139,123 2,292 Construction and real estate 47,413 7,875 55,288 62,064 8,366 50,343 593 Services 71,358 9,625 80,983 85,565 20,117 78,583 973 Wholesale and retail 139,338 8,191 147,529 158,933 48,582 139,042 1,845 Transportation and communications 20,203 2,509 22,712 23,555 7,318 25,549 383 Banks and other financial institutions 8,193 3,753 11,946 11,946 1,541 10,565 129 Other industries 18,709 276 18,985 20,716 8,606 14,512 194 Individuals 42,632 41,175 83,807 88,315 6,382 82,456 1,253 Total domestic 500,711 79,965 580,676 613,836 163,791 540,173 7,662 Foreign: Total foreign (5) 95,289 40,239 135,528 151,212 67,235 123,313 3,032 Total 596,000 120,204 716,204 765,048 231,026 663,486 10,694 (1) Amounts represent the outstanding balances of nonaccrual loans. The MHFG Group’s policy for placing loans in nonaccrual status corresponds to the Group’s definition of impaired loans. (2) These impaired loans do not require an allowance for loan losses because the MHFG Group has sufficient collateral to cover probable loan losses. (3) The allowance for loan losses on impaired loans includes the allowance for groups of loans which were collectively evaluated for impairment, in addition to the allowance for those loans that were individually evaluated for impairment. The total carrying amount of the groups of loans which were collectively evaluated for impairment at March 31, 2019 and 2020 was ¥257,099 million and ¥260,596 million, respectively. (4) Amounts represent the amount of interest income on impaired loans recognized on a cash basis and included in Interest income on loans in the consolidated statements of income. (5) The majority of total foreign consist of commercial and industrial loans.
Troubled Debt Restructurings Entered Modified Periods by Type of Concession Granted	The following table presents modified loans that were determined to be TDRs during the fiscal years ended March 31, 2019 and 2020: Loan forgiveness or debt to equity swaps Interest rate reduction and/or postponement of principal and/or interest Recorded investment (1) Charge-offs (in millions of yen) 2019 Domestic: Manufacturing — — 134,544 Construction and real estate — — 39,254 Services — — 87,468 Wholesale and retail — — 167,299 Transportation and communications — — 33,991 Banks and other financial institutions — — 17,286 Other industries — — 120 Individuals — — 42,330 Total domestic — — 522,292 Foreign: Total foreign (2) 984 1,964 44,033 Total 984 1,964 566,325 2020 Domestic: Manufacturing 689 3,806 148,564 Construction and real estate — — 31,803 Services — — 78,211 Wholesale and retail — 196 169,224 Transportation and communications — — 18,700 Banks and other financial institutions — — 16,962 Other industries — — 1,366 Individuals — — 14,000 Total domestic 689 4,002 478,830 Foreign: Total foreign (2) 466 4,906 114,159 Total 1,155 8,908 592,989 Notes: (1) Amounts represent the book values of loans immediately after the restructurings. (2) The majority of total foreign consist of commercial and industrial loans.
Payment Defaults Occurred During Periods with Respect to Loans Modified as Troubled Debt Restructurings within Previous Twelve Months	Recorded investment 2019 2020 (in millions of yen) Domestic: Manufacturing 1,173 3,752 Construction and real estate 121 345 Services 1,335 3,822 Wholesale and retail 15,087 19,018 Transportation and communications 878 824 Banks and other financial institutions 66 66 Other industries 1,650 — Individuals 2,152 2,545 Total domestic 22,462 30,372 Foreign: Total foreign 5,418 11,442 Total 27,880 41,814
Age Analysis of Past Due Loans	The table below presents an analysis of the age of the recorded investment in loans that are past due at March 31, 2019 and 2020: 30-59 past due 60-89 past due 90 days or more past due Total past due Current Total (in millions of yen) 2019 Domestic: Manufacturing 2,210 513 7,036 9,759 9,544,095 9,553,854 Construction and real estate 1,010 1,054 31,092 33,156 8,917,421 8,950,577 Services 633 196 3,494 4,323 5,012,648 5,016,971 Wholesale and retail 1,614 1,415 7,868 10,897 5,148,459 5,159,356 Transportation and communications 363 256 2,119 2,738 3,690,753 3,693,491 Banks and other financial institutions 3 484 6 493 4,345,096 4,345,589 Government and public institutions — — — — 2,358,904 2,358,904 Other industries 2 — 57 59 5,472,538 5,472,597 Individuals 27,139 11,013 28,965 67,117 9,790,688 9,857,805 Total domestic 32,974 14,931 80,637 128,542 54,280,602 54,409,144 Foreign: Total foreign (Note) 668 211 26,316 27,195 28,515,751 28,542,946 Total 33,642 15,142 106,953 155,737 82,796,353 82,952,090 2020 Domestic: Manufacturing 1,109 386 10,997 12,492 9,718,536 9,731,028 Construction and real estate 1,266 687 21,518 23,471 9,579,962 9,603,433 Services 792 548 6,714 8,054 5,984,457 5,992,511 Wholesale and retail 1,748 2,446 11,972 16,166 5,203,561 5,219,727 Transportation and communications 56 35 2,051 2,142 3,830,742 3,832,884 Banks and other financial institutions — — 109 109 4,634,333 4,634,442 Government and public institutions — — — — 2,198,805 2,198,805 Other industries 28 20 1,326 1,374 5,387,973 5,389,347 Individuals 21,376 10,876 34,793 67,045 9,361,289 9,428,334 Total domestic 26,375 14,998 89,480 130,853 55,899,658 56,030,511 Foreign: Total foreign (Note) 1,214 181 28,722 30,117 31,616,541 31,646,658 Total 27,589 15,179 118,202 160,970 87,516,199 87,677,169 Note: The majority of total foreign consist of commercial and industrial loans.

Allowance for loan losses (Tabl

Allowance for loan losses (Tables)	12 Months Ended
	Mar. 31, 2020
Changes in Allowance for Loan Losses, Allowance for Loan Losses and Loans Outstanding Disaggregated on Basis of Impairment Method, by Portfolio Segment	Changes in Allowance for loan losses by portfolio segment for the fiscal years ended March 31, 2018, 2019 and 2020 are shown below: Corporate Retail Other Total (in millions of yen) 2018 Balance at beginning of fiscal year 407,327 36,923 35,423 479,673 Provision (credit) for loan losses (123,470 ) (7,427 ) 4,535 (126,362 ) Charge-offs (44,621 ) (2,118 ) (9,123 ) (55,862 ) Recoveries 12,924 814 1,482 15,220 Net charge-offs (31,697 ) (1,304 ) (7,641 ) (40,642 ) Others (Note) (3,088 ) — 321 (2,767 ) Balance at end of fiscal year 249,072 28,192 32,638 309,902 2019 Balance at beginning of fiscal year 249,072 28,192 32,638 309,902 Provision (credit) for loan losses 31,693 (2,658 ) 3,424 32,459 Charge-offs (39,728 ) (2,856 ) (4,940 ) (47,524 ) Recoveries 11,019 552 2,532 14,103 Net charge-offs (28,709 ) (2,304 ) (2,408 ) (33,421 ) Others (Note) 847 — (2,586 ) (1,739 ) Balance at end of fiscal year 252,903 23,230 31,068 307,201 2020 Balance at beginning of fiscal year 252,903 23,230 31,068 307,201 Provision (credit) for loan losses 155,576 760 (136 ) 156,200 Charge-offs (33,971 ) (3,840 ) (6,547 ) (44,358 ) Recoveries 26,155 700 1,061 27,916 Net charge-offs (7,816 ) (3,140 ) (5,486 ) (16,442 ) Others (Note) (5,454 ) — (650 ) (6,104 ) Balance at end of fiscal year 395,209 20,850 24,796 440,855 Note: Others includes primarily foreign exchange translation. The table below presents Allowance for loan losses and loans outstanding by portfolio segment disaggregated on the basis of impairment method at March 31, 2019 and 2020: Corporate Retail Other Total (in millions of yen) 2019 Allowance for loan losses 252,903 23,230 31,068 307,201 of which individually evaluated for impairment 139,472 2,122 8,933 150,527 of which collectively evaluated for impairment 113,431 21,108 22,135 156,674 Loans (Note) 66,804,088 10,596,994 5,551,008 82,952,090 of which individually evaluated for impairment 539,893 20,886 54,319 615,098 of which collectively evaluated for impairment 66,264,195 10,576,108 5,496,689 82,336,992 2020 Allowance for loan losses 395,209 20,850 24,796 440,855 of which individually evaluated for impairment 231,941 1,704 5,443 239,088 of which collectively evaluated for impairment 163,268 19,146 19,353 201,767 Loans (Note) 71,840,922 10,112,617 5,723,630 87,677,169 of which individually evaluated for impairment 971,153 19,279 44,244 1,034,676 of which collectively evaluated for impairment 70,869,769 10,093,338 5,679,386 86,642,493 Note: Amounts represent loan balances before deducting unearned income and deferred loan fees.

Premises and equipment (Tables)

Premises and equipment (Tables)	12 Months Ended
	Mar. 31, 2020
Summary of Premises and Equipment	Premises and equipment at March 31, 2019 and 2020 consist of the following: 2019 2020 (in millions of yen) Land 563,032 557,943 Buildings 826,781 657,774 Equipment and furniture 472,186 442,302 Leasehold improvements 97,508 228,383 Construction in progress 37,174 73,164 Software 1,366,481 1,359,120 Total 3,363,162 3,318,686 Less: Accumulated depreciation and amortization 1,462,210 1,462,438 Premises and equipment—net 1,900,952 1,856,248

Goodwill and intangible assets

Goodwill and intangible assets (Tables)	12 Months Ended
	Mar. 31, 2020
Changes in Goodwill	The changes in Goodwill during the fiscal years ended March 31, 2018, 2019 and 2020 are as follows: 2018 2019 2020 (in millions of yen) Balance at beginning of fiscal year 95,176 95,184 95,151 Impairment losses recognized — — (2,155 ) Foreign exchange translation 8 (33 ) 1 Balance at end of fiscal year 95,184 95,151 92,997 Gross amount of goodwill (Note) 170,926 169,489 169,313 Accumulated impairment losses 75,742 74,338 76,316 Note: Goodwill is recorded at a designated reporting unit level for the purpose of assessing impairment. Goodwill is not allocated to the reportable segments in Note 31 “Business segment information.”
Gross Carrying Amount, Accumulated Amortization and Net Carrying Amount of Intangible Assets	The table below presents the gross carrying amount, accumulated amortization and net carrying amount of intangible assets, at March 31, 2019 and 2020: 2019 2020 Gross carrying amount Accumulated amortization Net carrying amount Gross carrying amount Accumulated amortization Net carrying amount (in millions of yen) Intangible assets subject to amortization: Customer relationships (Note) 126,882 61,630 65,252 126,979 70,904 56,075 Other 1,698 1,412 286 1,693 1,460 233 Total 128,580 63,042 65,538 128,672 72,364 56,308 Intangible assets not subject to amortization: Total 8,702 — 8,702 8,381 — 8,381 Total 137,282 63,042 74,240 137,053 72,364 64,689
Estimated Aggregate Amortization Expense in Respect of Intangible Assets	The table below presents the estimated aggregate amortization expense in respect of intangible assets for the next five years: (in millions of yen) Fiscal year ending March 31: 2021 8,237 2022 7,702 2023 7,184 2024 6,666 2025 6,154

Pledged assets and collateral (

Pledged assets and collateral (Tables)	12 Months Ended
	Mar. 31, 2020
Amounts Pledged as Collateral for Borrowings and for Other Purposes	The following amounts, by balance sheet classification, have been pledged as collateral for borrowings and for other purposes at March 31, 2019 and 2020: 2019 2020 (in billions of yen) Interest-bearing deposits in other banks 68 69 Trading account assets 4,137 5,705 Investments 6,076 4,155 Loans 4,055 3,887 Other assets 1,886 2,786 Total 16,222 16,602
Associated Liabilities Collateralized by Pledged Assets	The associated liabilities collateralized by the above assets at March 31, 2019 and 2020 are summarized below: 2019 2020 (in billions of yen) Deposits 386 1,057 Payables under repurchase agreements 3,435 5,480 Payables under securities lending transactions 1,675 1,094 Other short-term borrowings 519 4,014 Long-term debt 1,431 213 Total 7,446 11,858

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Mar. 31, 2020
Balances of Time Deposits and Certificates of Deposit Issued by Domestic Offices in Amounts of JPY10 Million or More and by Foreign Offices in Amounts of USD100,000 or More	The balances of time deposits and certificates of deposit issued by domestic offices in amounts of ¥10 million (approximately US$93 thousand at the Federal Reserve Bank of New York’s noon buying rate on March 31, 2020) or more and the balances of these deposits issued by foreign offices in amounts of US$100,000 or more at March 31, 2019 and 2020 are as follows: 2019 2020 (in millions of yen) Domestic offices: Time deposits 16,578,642 14,684,619 Certificates of deposit 5,643,303 7,558,770 Total 22,221,945 22,243,389 Foreign offices: Time deposits 17,606,520 18,008,751 Certificates of deposit 7,695,240 5,723,792 Total 25,301,760 23,732,543
Balance and Remaining Maturities of Time Deposits and Certificates of Deposit Issued by Domestic and Foreign Offices	The balance and remaining maturities of time deposits and certificates of deposit issued by domestic and foreign offices at March 31, 2020 are shown in the following table: Time deposits Certificates of deposit Total (in millions of yen) Domestic offices: Due in one year or less 19,660,222 7,418,470 27,078,692 Due after one year through two years 1,676,056 140,300 1,816,356 Due after two years through three years 1,159,144 — 1,159,144 Due after three years through four years 335,659 — 335,659 Due after four years through five years 397,591 — 397,591 Due after five years 212,416 — 212,416 Total 23,441,088 7,558,770 30,999,858 Foreign offices: Due in one year or less 17,936,190 5,565,541 23,501,731 Due after one year through two years 59,530 80,747 140,277 Due after two years through three years 9,536 11,224 20,760 Due after three years through four years 6,624 — 6,624 Due after four years through five years 2,788 66,280 69,068 Due after five years 3,268 — 3,268 Total 18,017,936 5,723,792 23,741,728 Total 41,459,024 13,282,562 54,741,586

Short-term borrowings and lon_2

Short-term borrowings and long-term debt (Tables)	12 Months Ended
	Mar. 31, 2020
Details of Other Short-Term Borrowings	Details of Other short-term borrowings at March 31, 2019 and 2020 are as follows: 2019 2020 (in millions of yen) Short-term notes issued by consolidated VIEs of asset-backed commercial paper programs (1) 22,339 54,658 Commercial paper and short-term notes issued by MHFG’s subsidiaries (1)(2) 1,274,382 730,089 Borrowings from the Bank of Japan 508,627 4,002,781 Other 189,478 126,957 Total 1,994,826 4,914,485 Notes: (1) Short-term notes are issued under the laws of Japan in the form of commercial paper. (2) The amounts of commercial paper and short-term notes issued by MHFG’s subsidiaries were ¥941,182 million and ¥333,200 million, respectively, at March 31, 2019, and ¥411,089 million and ¥319,000 million, respectively, at March 31, 2020.
Long-Term Debt with Original Maturities of More than One Year	Long-term debt with original maturities of more than one year at March 31, 2019 and 2020 is comprised of the following: 2019 2020 (in millions of yen) Obligations under finance leases 25,020 16,250 Loan participation borrowings 142,838 149,398 Senior borrowings and bonds 7,503,032 6,402,157 Subordinated borrowings and bonds 3,858,510 3,778,347 Total 11,529,400 10,346,152
Interest Rates and Maturities of Senior Borrowings and Bonds, and Subordinated Borrowings and Bonds	The following table presents the interest rates and maturities of senior borrowings and bonds, and subordinated borrowings and bonds: Interest rates (1) Maturities (2) 2019 2020 (%) (in millions of yen) Senior borrowings and bonds: fixed rate denominated in Japanese yen 0.00-8.10 Apr.2020 Jan.2050 2,057,156 549,647 fixed rate denominated in U.S. dollars 0.00-8.25 Apr.2020 Mar.2048 2,765,247 2,744,713 fixed rate denominated in other currencies 0.02-12.40 Apr.2020 Sep.2039 324,162 609,346 floating rate denominated in Japanese yen 0.00-51.60 Apr.2020 Mar.2050 656,029 606,095 floating rate denominated in U.S. dollars 0.00-37.20 Apr.2020 Dec.2059 1,493,617 1,682,540 floating rate denominated in other currencies 0.00-25.00 Jun.2020 Oct.2030 206,821 209,816 Total 7,503,032 6,402,157 Subordinated borrowings and bonds: fixed rate denominated in Japanese yen 0.39-4.26 Aug.2020 3,442,438 3,370,234 fixed rate denominated in U.S. dollars 4.30-4.70 Jul.2022 Oct.2025 416,072 408,113 Total 3,858,510 3,778,347 Total 11,361,542 10,180,504 Notes: (1) The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2020. (2) Maturity information disclosed is the range of maturities at March 31, 2020. (3) None of the long-term debt issuances above are convertible to common stock. (4) Certain debt agreements permit the MHFG Group to redeem the related debt, in whole or in part, prior to maturity at the MHFG Group’s option on terms specified in the respective agreements.
Contractual Maturities of Long-Term Debt	The following is a summary of contractual maturities of long-term debt subsequent to March 31, 2020: (in millions of yen) Fiscal year ending March 31: 2021 559,447 2022 1,430,157 2023 1,234,962 2024 697,214 2025 1,023,243 2026 and thereafter 5,401,129 Total 10,346,152

Other assets and liabilities (T

Other assets and liabilities (Tables)	12 Months Ended
	Mar. 31, 2020
Details of Other Assets and Liabilities	The following table sets forth 2019 2020 (in millions of yen) Other assets: Accounts receivable: Receivables from brokers, dealers and customers for securities transactions (1) 1,517,235 783,439 Other 400,676 358,702 Collateral pledged: Collateral pledged for derivative transactions 856,439 1,246,026 Margins provided for futures contracts 159,747 602,039 Other 857,814 941,167 Prepaid pension cost 850,472 711,981 ROU assets (2) — 613,068 Security deposits 123,317 107,294 Loans held for sale 24,921 60,084 Other 485,383 542,079 Total 5,276,004 5,965,879 Other liabilities: Accounts payable: Payables to brokers, dealers and customers for securities transactions (1) 2,572,315 2,161,075 Other 442,776 375,127 Guaranteed trust principal (3) 809,450 824,431 Lease liabilities (2) — 627,250 Collateral accepted: Collateral accepted for derivative transactions 589,411 846,426 Margins accepted for futures contracts 339,863 797,317 Unearned income (4) 126,594 122,072 Other 1,052,297 1,244,697 Total 5,932,706 6,998,395 Notes: (1) Receivables from brokers, dealers and customers for securities transactions included ¥555,938 million and ¥3,136 million of such receivables of consolidated VIEs at March 31, 2019 and 2020, respectively. Payables to brokers, dealers and customers for securities transactions included ¥620,766 million and ¥3,225 million of such payables of consolidated VIEs at March 31, 2019 and 2020, respectively. (2) ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 (3) Guaranteed trust principal, included in All other liabilities in the disclosure about consolidated VIEs in the accompanying balance sheets, is a liability of certain consolidated trust arrangements that meet the definition of a VIE for which the MHFG Group provides guarantees for the repayment of principal. See Note 24 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts. (4) Unearned income is primarily comprised of loan fees received from consumer loan customers when loans are made. This income is deferred and recognized in earnings over the life of the loan.

Preferred stock (Tables)

Preferred stock (Tables)	12 Months Ended
	Mar. 31, 2020
Preferred stock
Schedule of Stock by Class	The composition of preferred stock at March 31, 2018, 2019 and 2020 is as follows: March 31, 2018 March 31, 2019 March 31, 2020 Class of stock Authorized Issued Authorized Issued Authorized Issued (number of shares) Class XIV preferred stock 900,000,000 — 900,000,000 — 900,000,000 — Class XV preferred stock 900,000,000 — 900,000,000 — 900,000,000 — Class XVI preferred stock 1,500,000,000 — 1,500,000,000 — 1,500,000,000 —

Common stock (Tables)

Common stock (Tables)	12 Months Ended
	Mar. 31, 2020
Common Stock
Schedule of Stock by Class	The following table shows the changes in the number of issued shares of common stock during the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (shares) Balance at beginning of fiscal year 25,386,307,945 25,389,644,945 25,392,498,945 Issuance of new shares of common stock due to exercise of stock acquisition rights 3,337,000 2,854,000 — Balance at end of fiscal year 25,389,644,945 25,392,498,945 25,392,498,945

Accumulated other comprehensi_2

Accumulated other comprehensive income (loss), net of tax (Tables)	12 Months Ended
	Mar. 31, 2020
Changes in Each Component of AOCI	Changes in each component of AOCI for the fiscal years ended March 31, 2018, 2019 and 2020 are as follows: 2018 2019 2020 (in millions of yen) AOCI, balance at beginning of fiscal year, previously reported 1,521,163 1,741,894 164,021 Cumulative effect of change in accounting principles (1) — (1,535,142 ) (1,052 ) AOCI, balance at beginning of fiscal year, adjusted 1,521,163 206,752 162,969 Net unrealized gains (losses) on available-for-sale Balance at beginning of fiscal year, previously reported 1,461,302 1,556,585 22,019 Cumulative effect of change in accounting principles (1) — (1,525,064 ) — Balance at beginning of fiscal year, adjusted 1,461,302 31,521 22,019 Unrealized holding gains (losses) during year 282,141 (11,358 ) (22,566 ) Less: reclassification adjustments for losses (gains) included in net income (186,858 ) 1,856 (19,045 ) Change during year 95,283 (9,502 ) (41,611 ) Balance at end of fiscal year 1,556,585 22,019 (19,592 ) Foreign currency translation adjustments: Balance at beginning of fiscal year, previously reported (5,535 ) (35,076 ) (58,558 ) Cumulative effect of change in accounting principles (1) — — (1,052 ) Balance at beginning of fiscal year, adjusted (5,535 ) (35,076 ) (59,610 ) Foreign currency translation adjustments during year (26,936 ) (22,737 ) (49,888 ) Less: reclassification adjustments for losses (gains) included in net income (2,605 ) (745 ) (374 ) Change during year (29,541 ) (23,482 ) (50,262 ) Balance at end of fiscal year (35,076 ) (58,558 ) (109,872 ) Pension liability adjustments: Balance at beginning of fiscal year 65,396 220,385 196,446 Unrealized gains (losses) during year 157,737 (17,243 ) (122,219 ) Less: reclassification adjustments for losses (gains) included in net income (2,748 ) (6,696 ) (4,772 ) Change during year 154,989 (23,939 ) (126,991 ) Balance at end of fiscal year 220,385 196,446 69,455 Own credit risk adjustments (2) Balance at beginning of fiscal year, previously reported — — 4,114 Cumulative effect of change in accounting principles (1) — (10,078 ) — Balance at beginning of fiscal year, adjusted — (10,078 ) 4,114 Unrealized gains (losses) during year — 14,293 45,560 Less: reclassification adjustments for losses (gains) included in net income — (101 ) 841 Change during year — 14,192 46,401 Balance at end of fiscal year — 4,114 50,515 Total other comprehensive income (loss), net of tax attributable to MHFG shareholders 220,731 (42,731 ) (172,463 ) AOCI, balance at end of fiscal year 1,741,894 164,021 (9,494 ) Notes: (1) See Note 2 “Issued accounting pronouncements” for further details of the cumulative-effect adjustment for AOCI. (2) The MHFG Group adopted ASU No.2016-01
Amounts Reclassified Out of Accumulated Other Comprehensive Income into Net Income	The following table shows the amounts reclassified out of AOCI into net income during the fiscal year ended March 31, 2020: Before tax (1) Tax effect (2) Net of tax before allocation to noncontrolling interests Net of tax attributable to noncontrolling interests (2) Net of tax attributable to MHFG shareholders (in millions of yen) Amounts reclassified out of AOCI into net income: Affected line items in the consolidated statements of income: Net unrealized gains (losses) on available-for-sale 27,449 (8,410 ) 19,039 6 19,045 Investment gains (losses)—net Foreign currency translation adjustments 374 — 374 — 374 Investment gains (losses)—net Pension liability adjustments 6,618 (1,765 ) 4,853 (81 ) 4,772 Salaries and employee benefits Own credit risk adjustments (1,265 ) 387 (878 ) 37 (841 ) Other noninterest income (expenses) Total 33,176 (9,788 ) 23,388 (38 ) 23,350 Notes: (1) The financial statement line item in which the amounts in the Before tax column are reported in the Consolidated statements of income is listed to the right of the table. (2) The financial statement line items in which the amounts in the Tax effect and the Net of tax attributable to noncontrolling interest columns are reported in the consolidated statements of income are Income tax expense and Net income, respectively.

Regulatory matters (Tables)

Regulatory matters (Tables)	12 Months Ended
	Mar. 31, 2020
Capital Requirements and Regulatory Adjustments Over Transitional Period	The capital requirements and regulatory adjustments are being phased in over a transitional period as follows (italicized percentages indicate those still in transition periods): March 2019 March 2020 March 2021 March 2022 March 2023 Minimum Common Equity Tier 1 capital 4.5 % 4.5 % 4.5 % 4.5 % 4.5 % Minimum Tier 1 capital 6.0 % 6.0 % 6.0 % 6.0 % 6.0 % Minimum total capital 8.0 % 8.0 % 8.0 % 8.0 % 8.0 % Phase out of recognition of capital instruments that no longer qualify as capital 30.0 % 20.0 % 10.0 % 0.0 % 0.0 % Capital conservation buffer 2.5 % 2.5 % 2.5 % 2.5 % 2.5 % Countercyclical capital buffer (1) 0.05 % 0.01 % 0.01 % 0.01 % 0.01 % Additional loss absorbency requirements for G-SIBs D-SIBs (2) 1.0 % 1.0 % 1.0 % 1.0 % 1.0 % Minimum Leverage Ratio 3.0 % 3.0 % 3.0 % 3.0 % 3.5 % (3) Notes: (1) Figures assume that the countercyclical capital buffer will continue to be 0.01% after March 2020. (2) Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB D-SIB (3) This figure includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB
Capital Adequacy Ratios of MHFG, MHBK, and MHTB Calculated in Accordance with Japanese GAAP and Guidelines Established by Financial Services Agency	Capital adequacy ratios and leverage ratios accordance 2019 2020 Amount Ratio Amount Ratio (in billions of yen, except percentages) Consolidated: MHFG: Common Equity Tier 1 capital: Required (Note) 4,661 8.05 4,978 8.01 Actual 7,390 12.76 7,245 11.65 Tier 1 capital: Required (Note) 5,529 9.55 5,910 9.51 Actual 9,232 15.94 9,024 14.52 Total risk-based capital: Required (Note) 6,687 11.55 7,152 11.51 Actual 10,918 18.85 10,722 17.25 Leverage Ratio: Required 6,257 3.00 6,629 3.00 Actual 9,232 4.42 9,024 4.08 MHBK: Common Equity Tier 1 capital: Required 2,388 4.50 2,567 4.50 Actual 6,690 12.60 6,501 11.39 Tier 1 capital: Required 3,184 6.00 3,422 6.00 Actual 8,527 16.06 8,275 14.50 Total risk-based capital: Required 4,246 8.00 4,563 8.00 Actual 10,098 19.02 9,865 17.29 Leverage Ratio: Required 5,758 3.00 6,160 3.00 Actual 8,527 4.44 8,275 4.02 MHTB: Common Equity Tier 1 capital: Required 95 4.50 93 4.50 Actual 500 23.67 489 23.64 Tier 1 capital: Required 127 6.00 124 6.00 Actual 501 23.70 489 23.66 Total risk-based capital: Required 169 8.00 165 8.00 Actual 505 23.87 491 23.74 Leverage Ratio: Required 229 3.00 216 3.00 Actual 501 6.55 489 6.79 Non-consolidated: MHBK: Common Equity Tier 1 capital: Required 2,272 4.50 2,403 4.50 Actual 6,363 12.60 6,130 11.47 Tier 1 capital: Required 3,029 6.00 3,204 6.00 Actual 8,199 16.23 7,905 14.80 2019 2020 Amount Ratio Amount Ratio (in billions of yen, except percentages) Total risk-based capital: Required 4,039 8.00 4,272 8.00 Actual 9,757 19.32 9,482 17.75 Leverage Ratio: Required 5,517 3.00 5,884 3.00 Actual 8,199 4.45 7,905 4.03 MHTB: Common Equity Tier 1 capital: Required 94 4.50 93 4.50 Actual 494 23.58 475 23.10 Tier 1 capital: Required 126 6.00 123 6.00 Actual 494 23.58 475 23.10 Total risk-based capital: Required 168 8.00 165 8.00 Actual 498 23.75 477 23.18 Leverage Ratio: Required 227 3.00 214 3.00 Actual 494 6.53 475 6.66 Note: The required ratios disclosed above, at March 31, 2019 and 2020, include the capital conservation buffer G-SIBs D-SIBs

Earnings per common share (Tabl

Earnings per common share (Tables)	12 Months Ended
	Mar. 31, 2020
Computation of Basic and Diluted Earnings Per Common Share	The following table sets forth the computation of basic and diluted earnings per common share for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Net income: Net income attributable to MHFG common shareholders 577,608 84,471 150,195 Effect of dilutive securities — — — Net income attributable to common shareholders after assumed conversions 577,608 84,471 150,195 2018 2019 2020 (thousands of shares) Shares: Weighted average common shares outstanding 25,366,345 25,362,376 25,373,681 Effect of dilutive securities: Stock options and the common shares of MHFG under the stock compensation programs (Note) 7,586 4,522 1,583 Weighted average common shares after assumed conversions 25,373,931 25,366,898 25,375,264 2018 2019 2020 (in yen) Earnings per common share: Basic net income per common share 22.77 3.33 5.92 Diluted net income per common share (Note) 22.76 3.33 5.92 Note: For the fiscal year ended March 31, 2020, the performance-based plan under the stock compensation programs could potentially dilute earnings per common share but were not included in the computation of diluted earnings per common share due to their antidilutive effects.

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Mar. 31, 2020
Components of Income Tax Expense	The following table presents the components of Income tax expense for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Current: Domestic 130,573 116,695 96,231 Foreign 47,020 49,871 52,885 Total current tax expense 177,593 166,566 149,116 Deferred: Domestic 58,078 (162,475 ) (111,341 ) Foreign 1,933 5,244 9,400 Total deferred tax expense (benefit) 60,011 (157,231 ) (101,941 ) Total income tax expense 237,604 9,335 47,175
Detailed Amounts of Tax Effects of Items Recorded Directly in Equity	The preceding table does not reflect the tax effects of items recorded directly in Equity for the fiscal years ended March 31, 2018, 2019 and 2020. The detailed amounts recorded directly in Equity are as follows: 2018 2019 2020 (in millions of yen) Net unrealized gains (losses) on available-for-sale Unrealized gains (losses) 123,186 (3,940 ) (10,012 ) Less: reclassification adjustments (82,828 ) 889 (8,410 ) Total 40,358 (3,051 ) (18,422 ) Pension liability adjustments: Unrealized gains (losses) 66,331 (6,558 ) (52,888 ) Less: reclassification adjustments 190 (2,370 ) (1,765 ) Total 66,521 (8,928 ) (54,653 ) Own credit risk adjustments (Note) Unrealized gains (losses) — 3,033 5,052 Less: reclassification adjustments — (47 ) 387 Total — 2,986 5,439 Total tax effect before allocation to noncontrolling interests 106,879 (8,993 ) (67,636 ) Note: The MHFG Group adopted ASU No.2016-01
Reconciliation of Income Tax Expense at Effective Statutory Tax Rate to Actual Income Tax Expense	The following table shows a reconciliation of Income tax expense at the effective statutory tax rate to the actual income tax expense for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen, except tax rates) Income before income tax expense 839,298 85,060 153,490 Effective statutory tax rate 30.86 % 30.62 % 30.62 % Income tax calculated at the statutory tax rate 259,007 26,045 46,999 Income not subject to tax (9,312 ) (8,861 ) (7,758 ) Expenses not deductible for tax purposes 1,421 1,389 1,290 Tax rate differentials of subsidiaries (2,696 ) (3,522 ) (5,756 ) Change in valuation allowance (9,102 ) (2,444 ) 5,984 Noncontrolling interest income (loss) of consolidated VIEs (5,928 ) 3,475 14,796 Effect of enacted change in tax rates 6,863 (1) (11 ) (210 ) Change in unrecognized tax benefits — 9,420 — Other (2) (2,649 ) (16,156 ) (3) (8,170 ) Income tax expense 237,604 9,335 47,175 Notes: (1) On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act, which includes a reduction in the U.S. federal corporate income tax rate from 35% to 21%. The decrease in the Group’s balance of net deferred tax assets, reflecting such tax rate reductions, was recognized as an increase to Income tax expense in the fiscal year ended March 31, 2018. The MHFG Group has completed its analysis and accounting under Staff Accounting Bulletin No. 118 for the effects of the Act. (2) Change in undistributed earnings of subsidiaries of ¥(1,972) million and ¥(21,347) million have been reclassified to Other for the fiscal years ended March 31, 2018 and 2019, respectively, in order to conform to the current period’s presentation. (3) In the fiscal year ended March 31, 2019, the MHFG Group derecognized the majority of deferred tax liabilities for undistributed earnings of foreign subsidiaries because the Group has intent and ability to reinvest those earnings indefinitely in certain foreign subsidiaries.
Components of Net Deferred Tax Assets (Liabilities)	The components of net deferred tax assets (liabilities) at March 31, 2019 and 2020 are as follows: 2019 2020 (in millions of yen) Deferred tax assets: Lease liabilities (1) — 191,873 Allowance for loan losses 122,585 165,665 Premises and equipment 73,944 77,513 Available-for-sale — 5,532 Derivative financial instruments 48,487 4,647 Investments — 3,563 Net operating loss carryforwards (2) 167,755 163,264 Other 216,568 203,004 629,339 815,061 Valuation allowance ( 2 ) (158,581 ) (165,278 ) Deferred tax assets, net of valuation allowance 470,758 649,783 Deferred tax liabilities: Prepaid pension cost and accrued pension liabilities 247,694 202,930 ROU assets (1) — 188,591 Trading securities 9,158 58,266 Investments 198,495 — Available-for-sale 12,426 — Other 61,330 89,157 Deferred tax liabilities 529,103 538,944 Net deferred tax assets (liabilities) (58,345 ) 110,839 Notes: (1) ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 (2) The amount includes ¥107,246 million and ¥101,498 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2019 and 2020, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥88,294 million and ¥86,591 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.
Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction	The following table and accompanying footnotes provide a breakdown of deferred tax assets and the valuation allowance recognized in respect of net operating loss carryforwards by tax jurisdiction and by year of expiration as of March 31, 2019 and 2020: Deferred tax assets Valuation allowance Deferred tax assets, net of valuation allowance (in billions of yen) 2019 Japan (1) 111 (92 ) 19 The United States 8 — 8 The United Kingdom (2) 46 (46 ) — Others 3 (2 ) 1 Total 168 (140 ) 28 2020 Japan (3) 110 (92 ) 18 The United States 3 — 3 The United Kingdom (2) 47 (47 ) — Others 3 (2 ) 1 Total 163 (141 ) 22 Notes: (1) ¥107 billion of the Japan deferred tax assets of ¥111 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026. (2) The United Kingdom net operating loss carryforwards may be carried forward indefinitely for tax purposes. (3) ¥101 billion of the Japan deferred tax assets of ¥110 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026.
Roll-forward Valuation Allowance	The following table presents a roll-forward of the valuation allowance for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Balance at beginning of fiscal year 438,344 163,358 158,581 Changes that directly affected Income tax expense (9,102 ) (2,444 ) 5,984 Changes that did not affect Income tax expense: Expiration of net operating loss carryforwards (264,234 ) — — Others (1,650 ) (2,333 ) 713 Total (265,884 ) (2,333 ) 713 Balance at end of fiscal year 163,358 158,581 165,278
Net Operating Losses Carryforwards by Expiration Date	These carryforwards are scheduled to expire as follows: Net operating loss carryforwards (in billions of yen) Fiscal year ending March 31: 2021 — 2022 — 2023 6 2024 3 2025 — 2026 and thereafter (Note) 628 Total 637 Note: Including the net operating loss carryforwards which may be carried forward indefinitely in the United Kingdom.
Roll-forward of Unrecognized Tax Benefits	The following table is a roll-forward of unrecognized tax benefits for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Total unrecognized tax benefits at beginning of fiscal year 1,867 2,345 12,323 Gross amount of increases related to positions taken during prior years 224 9,550 199 Gross amount of increases related to positions taken during the current year 351 330 328 Amount of decreases related to settlements — — (9,420 ) Foreign exchange translation (97 ) 98 (56 ) Total unrecognized tax benefits at end of fiscal year 2,345 12,323 3,374

Pension and other employee be_2

Pension and other employee benefit plans (Tables)	12 Months Ended
	Mar. 31, 2020
Components of Net Periodic Benefit Cost of Severance Indemnities and Pension Plans	The following table presents the components of net periodic cost of the severance indemnities and pension plans for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Service cost-benefits earned during the fiscal year 43,649 43,698 45,697 Interest costs on projected benefit obligations 7,471 6,933 5,590 Expected return on plan assets (34,916 ) (38,518 ) (40,551 ) Amortization of prior service cost (benefits) 214 152 121 Amortization of net actuarial loss (gain) 411 (7,886 ) (5,873 ) Special termination benefits 3,960 2,929 9,793 Net periodic benefit cost 20,789 7,308 14,777
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) Before-Tax	Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before-tax 2019 2020 (in millions of yen) Net actuarial gain (loss) (21,300 ) (169,963 ) Amortization of net actuarial loss (gain) (7,886 ) (5,873 ) Prior service benefits (cost) (109 ) (2,734 ) Amortization of prior service cost (benefits) 152 121 Total recognized in other comprehensive income (loss) before-tax (29,143 ) (178,449 )
Weighted-Average Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost	2018 2019 2020 Weighted-average assumptions used to determine benefit obligations at fiscal year end: Discount rates 0.43 % 0.34 % 0.37 % Rates of increase in future compensation levels 1.80-4.80 % 1.80-4.80 % 1.80-4.80 % Weighted-average assumptions used to determine net periodic benefit cost during the year: Discount rates 0.47 % 0.43 % 0.34 % Rates of increase in future compensation levels 1.80-4.80 % 1.80-4.80 % 1.80-4.80 % Expected rates of return on plan assets 1.58 % 1.60 % 1.68 %
Combined Funded Status and Amounts Recognized in Accompanying Consolidated Balance Sheets	The following table sets forth the combined funded status and amounts recognized in the accompanying consolidated balance sheets at March 31, 2019 and 2020 for the plans of MHFG and its subsidiaries: 2019 2020 (in millions of yen) Change in benefit obligations: Benefit obligations at beginning of fiscal year 1,559,356 1,590,818 Service cost 43,698 45,697 Interest cost 6,933 5,590 Plan participants’ contributions 1,229 1,200 Amendments 109 2,734 Actuarial loss (gain) 49,085 4,507 Foreign exchange translation (817 ) (5,605 ) Benefits paid (52,618 ) (52,902 ) Lump-sum (16,157 ) (20,743 ) Benefit obligations at end of fiscal year 1,590,818 1,571,296 Change in plan assets: Fair value of plan assets at beginning of fiscal year 2,405,730 2,413,556 Actual return (negative return) on plan assets 66,652 (125,549 ) Foreign exchange translation (390 ) (4,268 ) Partial withdrawal of assets from employee retirement benefits trusts (Note) (27,534 ) — Employer contributions 20,487 20,587 Plan participants’ contributions 1,229 1,200 Benefits paid (52,618 ) (52,902 ) Fair value of plan assets at end of fiscal year 2,413,556 2,252,624 Funded status 822,738 681,328 Amounts recognized in the consolidated balance sheets consist of: Prepaid pension cost 850,472 711,981 Accrued pension liability (27,734 ) (30,653 ) Net amount recognized 822,738 681,328 Amounts recognized in Accumulated other comprehensive income (loss) before-tax Prior service benefits (cost) (1,309 ) (3,914 ) Net actuarial gain (loss) 262,044 86,200 Net amount recognized 260,735 82,286 Note: During the fiscal year ended March 31, 2019, a subsidiary of MHFG partially withdrew assets from employee retirement benefit trusts, which were established for the payment of employees’ severance pay and retirement pensions. Overall, the trusts remain in overfunded status as of March 31, 2019. No gains or losses have been recognized as a result of this transaction.
Plans with Projected Benefit Obligations in Excess of Plan Assets and Plans with Accumulated Benefit Obligations in Excess of Plan Assets	The following table shows the projected benefit obligations and the fair value of plan assets for the plans of MHFG and its subsidiaries with projected benefit obligations in excess of plan assets, and the accumulated benefit obligations and the fair value of plan assets for the plans with accumulated benefit obligations in excess of plan assets at March 31, 2019 and 2020: 2019 2020 (in millions of yen) Plans with projected benefit obligations in excess of plan assets: Projected benefit obligations 61,579 63,619 Fair value of plan assets 33,845 32,966 Plans with accumulated benefit obligations in excess of plan assets: Accumulated benefit obligations 61,579 63,619 Fair value of plan assets 33,845 32,966 Note: The plans with projected benefit obligations in excess of plan assets include those with accumulated benefit obligations in excess of plan assets.
Target Allocation for Plan Assets Excluding those of Employee Retirement Benefit Trusts	MHFG and certain subsidiaries’ target allocation for the plan assets, excluding those of the employee retirement benefit trusts, at March 31, 2020 is as follows: Asset category Asset ratio Japanese equity securities 5.00 % Japanese debt securities 34.00 % Foreign equity securities 25.00 % Foreign debt securities 23.00 % General account of life insurance companies 11.00 % Other 2.00 % Total 100.00 % Note: General account of life insurance companies is a contract with life insurance companies which guarantees payments of principal and predetermined interest payments.
Fair Value of Plan Assets by Asset Category	The following table presents the fair value of plan assets of MHFG and its subsidiaries at March 31, 2019 and 2020, by asset class. For the detailed information on fair value measurements, including descriptions of Level 1, 2 and 3 of the fair value hierarchy and the valuation methodologies, see Note 27 “Fair value.” 2019 2020 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in billions of yen) Japanese equity securities: Common stocks (1) 1,317 — — 1,317 1,194 — — 1,194 Pooled funds (2) 11 4 — 15 10 4 — 14 Japanese debt securities: Government bonds 190 — — 190 196 — — 196 Pooled funds (2) — 10 — 10 — 9 — 9 Other — 24 — 24 — 23 — 23 Foreign equity securities: Common stocks 120 — — 120 101 — — 101 Pooled funds (2) — 5 — 5 — 4 — 4 Foreign debt securities: Government bonds 178 6 — 184 188 7 — 195 Pooled funds (2) — 10 — 10 — 11 — 11 Other — 18 — 18 — 20 — 20 General account of life insurance companies (3) — 111 — 111 — 111 — 111 Other 79 (4) 4 — 83 68 (4) 1 — 69 Plan assets measured at net asset value (5) 327 306 Total assets at fair value 1,895 192 — 2,414 1,757 190 — 2,253 Notes: (1) This class represents equity securities held in the employee retirement benefit trusts of ¥1,317 billion and ¥1,194 billion carried at fair value at March 31, 2019 and 2020, respectively, which are well-diversified across industries. (2) These classes primarily include pension investment fund trusts. Investments in these classes are generally measured at fair value and can be redeemed within a short-term period upon request. (3) Investments in this class are measured at conversion value, which is equivalent to fair value. (4) Amounts primarily include cash and short-term assets carried at fair value. (5) In accordance with ASC 820, certain plan assets that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy.
Forecasted Benefit Payments Including Effect of Expected Future Service	The following table presents forecasted benefit payments including the effect of expected future service for the fiscal years indicated: (in millions of yen) Fiscal year ending March 31: 2021 70,325 2022 70,623 2023 71,165 2024 72,469 2025 73,118 2026-2030 346,908

Stock-based compensation (Table

Stock-based compensation (Tables)	12 Months Ended
	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of Stock-Based Compensation Plan	The following is a roll-forward of MHFG Stock Plan for the fiscal year ended March 31, 2020: Number of shares Weighted-average exercise price Weighted-average remaining contractual term Aggregate intrinsic value (in yen) (in years) (in millions of yen) Outstanding at beginning of fiscal year 4,245,000 1 Exercised during fiscal year 2,968,000 1 Outstanding at end of fiscal year 1,277,000 1 13.91 157 Exercisable at end of fiscal year — — — —
Activities Related to Stock Compensation Program	The following table presents activities related to the stock compensation programs for the fiscal years ended March 31, 2019 and 2020: Stock Compensation I Stock Compensation II 2019 Number of shares Weighted-average grant-date fair value Number of shares Weighted-average grant-date fair value (per share in yen) (per share in yen) Nonvested at the beginning of the year — — 13,319,406 182.04 Granted during fiscal year 3,770,065 189.24 6,906,635 189.24 Vested during fiscal year 3,770,065 189.24 5,068,949 187.48 Forfeited during fiscal year — — — — Nonvested at the end of the year — — 15,157,092 183.50 Stock Compensation I Stock Compensation II 2020 Number of shares Weighted-average grant-date fair value Number of shares Weighted-average grant-date fair value (per share in yen) (per share in yen) Nonvested at the beginning of the year — — 15,157,092 183.50 Granted during fiscal year 5,748,997 159.59 3,281,003 159.59 Vested during fiscal year 5,748,997 159.59 7,014,809 182.07 Forfeited during fiscal year — — — — Nonvested at the end of the year — — 11,423,286 177.51
Total Fair Value of Stock Compensation that Vested and Common Stock Acquired	The following table presents the total fair value of the stock compensation that vested and the total amount of the common stock acquired from the stock market by the trustee for the fiscal years ended March 31, 2019 and 2020: 2019 2020 Stock Compensation I Stock Compensation II Stock Compensation I Stock Compensation II (in millions of yen) Fair value of vested shares 713 930 917 1,090 Common stock shares acquired 713 1,307 917 524
Schedule Of Stock-Based Compensation Expense	The following table presents the compensation cost recognized in the stock compensation programs for the fiscal years ended March 31, 2018, 2019 and 2020: 2018 2019 2020 (in millions of yen) Stock Compensation I — 713 917 Stock Compensation II 868 1,287 1,247

Derivative financial instrume_2

Derivative financial instruments (Tables)	12 Months Ended
	Mar. 31, 2020
Summary of Notional and Fair Value Amounts of Derivative Instruments Outstanding	The following table summarizes the notional and fair value amounts of derivative instruments outstanding as of March 31, 2019 and 2020. The fair values of derivatives are presented on a gross basis ; Fair value Derivative receivables (2) Derivative payables (2) 2019 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,052,267 — 5,786 — 5,610 Foreign exchange contracts 166,383 — 1,959 — 1,758 Equity-related contracts 5,181 — 125 — 142 Credit-related contracts 2,939 — 18 — 17 Other contracts 438 — 16 — 14 Total 1,227,208 — 7,904 — 7,541 Fair value Derivative receivables (2) Derivative payables (2) 2020 Notional amount (1) Designated as hedges Not designated as hedges Designated as hedges Not designated as hedges (in billions of yen) Interest rate contracts 1,123,546 — 7,232 — 6,788 Foreign exchange contracts 185,359 — 2,926 — 2,899 Equity-related contracts 6,684 — 310 — 266 Credit-related contracts 4,676 — 30 — 29 Other contracts 400 — 38 — 39 Total 1,320,665 — 10,536 — 10,021 Notes: (1) Notional amount includes the sum of gross long and gross short third-party contracts. (2) Derivative receivables and payables are recorded in Trading account assets and Trading account liabilities, respectively.
Summary of Notional and Fair Value Amounts of Credit Derivatives	The following table summarizes the notional and fair value amounts of credit derivatives at March 31, 2019 and 2020: 2019 2020 Notional amount Fair value Notional amount Fair value (in billions of yen) Credit protection written: Investment grade 1,266 12 1,400 (5 ) Non-investment 199 3 416 — Total 1,465 15 1,816 (5 ) Credit protection purchased 1,628 (14 ) 3,028 6 Note: The rating scale is based upon either the external ratings or the internal ratings of the underlying reference credit. The lowest investment grade rating is considered to be BBB - non-investment Non-investment
Maximum Potential Amount of Future Payments for Credit Protection Written by Expiration Period	The following table shows the maximum potential amount of future payments for credit protection written by expiration period at March 31, 2019 and 2020: Maximum payout/Notional amount 2019 2020 (in billions of yen) One year or less 326 270 After one year through five years 1,057 1,368 After five years 82 178 Total 1,465 1,816 Note: The maximum potential amount of future payments is the aggregate notional amount of the credit derivatives where the Group wrote the credit protection, and it has not been reduced by the effect of any amounts that the Group may possibly collect on the underlying assets and the related cash flows, nor netted against that of credit protection purchased.
Quantitative Information about Derivative Instruments with Credit-risk-related Contingent Features	The following table shows the quantitative information about derivative instruments with credit-risk-related contingent features at March 31, 2019 and 2020: 2019 2020 (in billions of yen) Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions 511 888 Collateral provided to counterparties in the normal course of business 489 818 Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered 22 70
Not Designated as Hedging Instrument
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table summarizes gains and losses on derivatives not designated or qualifying as hedges during the fiscal years ended March 31, 2018, 2019 and 2020: Gains (losses) recorded in income 2018 2019 2020 (in millions of yen) Interest rate contracts (63,260 ) 127,242 388,289 Foreign exchange contracts 61,046 6,748 (111,920 ) Equity-related contracts (1) (94,607 ) 37,875 217,744 Credit-related contracts (2) (2,830 ) (467 ) 8,046 Other contracts 6,330 (1,455 ) (21,143 ) Total (93,321 ) 169,943 481,016 Notes: (1) The net gains (losses) excluded from the assessment of the effectiveness of fair value hedges is not included in the above table. (2) Amounts include the net gains (losses) of ¥(754 ) )
Fair Value Hedging | Designated as Hedging Instrument
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table summarizes gains and losses information related to fair value hedges for the fiscal year ended March 31, 2018: Gains (losses) recorded in income 2018 Derivatives Hedged items Hedge ineffectiveness Net gain (loss) excluded from assessment of effectiveness (in millions of yen) Equity-related contracts (23,832 ) 19,631 — (4,201 ) Total (23,832 ) 19,631 — (4,201 )
Net Investment Hedging | Designated as Hedging Instrument
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table summarizes gains and losses information related to net investment hedges for the fiscal years ended March 31, 2018, 2019 and 2020: Gains (losses) recorded in other comprehensive income (“OCI”) 2018 2019 2020 (in millions of yen) Financial instruments hedging foreign exchange risk 60 7,512 418 Total 60 7,512 418 Note: Related to the net investment hedges, gains (losses) of ¥186 million and ¥(1,336) million were reclassified from Accumulated other comprehensive income to earnings for the fiscal years ended March 31, 2019 and 2020, respectively. No amount related to the net investment hedges was reclassified from Accumulated other comprehensive income to earnings for the fiscal year ended March 31, 2018.

Commitments and contingencies (

Commitments and contingencies (Tables)	12 Months Ended
	Mar. 31, 2020
Summary of Maximum Potential Amount of Future Payments under Guarantees	The MHFG Group, when necessary, requires collateral such as cash, investment securities and real estate or third-party guarantees depending on the amount of credit risk involved, and employs means such as sub-participation 2019 Maximum potential/Contractual Amount by expiration period One year or less After one year After five years (in billions of yen) Performance guarantees 2,307 1,265 878 164 Guarantees on loans 289 164 46 79 Guarantees on securities 145 91 54 — Other guarantees 2,324 1,447 834 43 Guarantees for the repayment of trust principal 65 — 47 18 Liabilities of trust accounts 362 61 148 153 Derivative financial instruments 14,170 5,807 6,434 1,929 2020 Maximum potential/Contractual or Notional amount Amount by expiration period One year or less After one year through five years After five years (in billions of yen) Performance guarantees 2,456 1,511 735 210 Guarantees on loans 301 204 34 63 Guarantees on securities 110 22 88 — Other guarantees 2,314 1,925 319 70 Guarantees for the repayment of trust principal 59 — 42 17 Liabilities of trust accounts 446 80 201 165 Derivative financial instruments 21,756 11,045 7,951 2,760
Summary of Contractual Amounts with Regard to Undrawn Commitments	The table below summarizes the contractual amounts with regard to these undrawn commitments at March 31, 2019 and 2020: 2019 2020 (in billions of yen) Commitments to extend credit (Note) 76,857 76,633 Commercial letters of credit 778 690 Total 77,635 77,323 Note: Commitments to extend credit include commitments to invest in securities.
Schedule of Balance Sheet Information Related to operating lease	The following table presents the consolidated balance sheet information related to operating leases as of March 31, 2020: As of March 31, 2020 (in millions of yen, except for remaining ROU assets (Note) 613,068 Lease liabilities (Note) 627,250 Weighted average: Remaining lease term 15.7 years Discount rate 0.55 % Note: ROU assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets.
Schedule of operating lease cost and supplemental cash flow information	The following table presents lease cost and supplemental information related to operating leases for the fiscal year ended March 31, 2020: Fiscal year ended March 31, 2020 (in millions of yen) Lease cost (Note) 126,840 ROU assets obtained in exchange for new lease liabilities 60,047 Operating cash flows 102,066 Note: Lease cost for operating leases are included in Occupancy expenses
Future Minimum Lease Payments for Capitalized Leases and Rental Payments for Operating Leases	The following table shows future lease payments under operating leases as of March 31, 2020: As of March 31, 2020 (in millions of yen) Fiscal year ending March 31: 2021 93,997 2022 68,268 2023 54,377 2024 47,608 2025 41,539 2026 and thereafter 346,741 Total lease payments 652,530 Amount representing interest 25,280 Total lease liabilities for operating leases 627,250
Performance guarantees, Guarantees on loans, Guarantees on securities and Other guarantees
Summary of Maximum Potential Amount of Future Payments under Guarantees	The table below presents the maximum potential amount of future payments of performance guarantees, guarantees on loans, guarantees on securities and other guarantees classified based on internal ratings at March 31, 2019 and 2020: 2019 2020 (in billions of yen) Investment grade 4,124 4,233 Non-investment 941 948 Total 5,065 5,181

Variable interest entities an_2

Variable interest entities and securitizations (Tables)	12 Months Ended
	Mar. 31, 2020
Schedule of Variable Interest Entities	The table below shows the consolidated assets of the Group’s consolidated VIEs as well as total assets and maximum exposure to loss for its significant unconsolidated VIEs, in which the Group has determined that its maximum exposure to loss is greater than specific thresholds or meets certain other criteria as of March 31, 2019 and 2020: Consolidated VIEs Significant unconsolidated VIEs 2019 Consolidated assets Total assets Maximum exposure to loss (in billions of yen) Asset-backed commercial paper/loan programs 2,249 — — Asset-backed securitizations 571 70 8 Investments in securitization products 372 — — Investment funds 2,836 1,280 410 Trust arrangements and other 20 — — Total 6,048 1,350 418 Consolidated VIEs Significant unconsolidated VIEs 2020 Consolidated assets Total assets Maximum exposure to loss (in billions of yen) Asset-backed commercial paper/loan programs 2,160 — — Asset-backed securitizations 572 77 7 Investments in securitization products 370 — — Investment funds 2,694 2,299 514 Trust arrangements and other 19 — — Total 5,815 2,376 521
Unconsolidated VIEs
Schedule of Variable Interest Entities	The tables below present the carrying amounts and classification of assets and liabilities on the MHFG Group’s balance sheets that relate to its variable interests in significant unconsolidated VIEs, as of March 31, 2019 and 2020: Assets on balance sheets related to unconsolidated VIEs: 2019 2020 (in billions of yen) Trading account assets 104 108 Investments 168 267 Loans 71 55 Total 343 430 Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs: 2019 2020 (in billions of yen) Payables under securities lending transactions 47 47 Trading account liabilities 1 2 Total 48 49 Maximum exposure to loss (Note) 418 521 Note: This represents the maximum amount the Group could possibly be required to record in its consolidated statements of income associated with on-balance-sheet off-balance-sheet

Noninterest income (Tables)

Noninterest income (Tables)	12 Months Ended
	Mar. 31, 2020
Summary of Noninterest Income	Details of Noninterest income for the fiscal years ended March 31, 2018, 2019 and 2020 are as follows: 2018 2019 2020 (in millions of yen) Fee and commission income: Securities-related business (1) 180,122 145,270 139,124 Deposits and lending business (2) 156,426 152,283 157,420 Remittance business (1) 110,054 110,382 112,275 Asset management business (1) 100,765 97,852 98,720 Trust related business (1) 121,808 124,843 129,298 Agency business (1) 37,397 36,466 31,879 Guarantee related business (3) 28,258 28,582 28,974 Fees for other customer services (1) 130,881 157,612 170,195 Total Fee and commission income 865,711 853,290 867,885 Foreign exchange gains (losses)—net (3) 91,793 93,577 44,345 Trading account gains (losses)—net (2) 236,982 328,841 745,692 Investment gains (losses)—net: Debt securities (3) 7,757 (3,842 ) 31,032 Equity securities (3) 289,400 (155,947 ) (557,391 ) Equity in earnings (losses) of equity method investees—net (3) 24,342 29,172 34,012 Gains on disposal of premises and equipment (3) 8,225 5,145 2,583 Other noninterest income (2) (4) 80,453 72,135 139,582 Total 1,604,663 1,222,371 1,307,740 Notes: (1) These amounts are revenues from contracts within the scope of ASC 606, “Revenue from contracts with customers ” (“ASC 606”). (2) Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606. (3) These amounts are revenues from contracts that do not meet the scope of ASC 606. (4) These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 27 “Fair value” for further details.

Trading account gains and los_2

Trading account gains and losses (Tables)	12 Months Ended
	Mar. 31, 2020
Trading Account Gains And Losses [Abstract]
Net Trading Gains and Losses	Net trading gains (losses) for the fiscal years ended March 31, 2018, 2019 and 2020 are comprised of the following: 2018 2019 2020 (in millions of yen) Trading account gains (losses)—net: Trading securities 333,749 158,162 267,514 Derivative contracts: Interest rate contracts (63,260 ) 127,242 388,289 Foreign exchange contracts (1) 61,046 6,748 (111,920 ) Equity-related contracts (2) (98,807 ) 37,875 217,744 Credit-related contracts (3) (2,076 ) 269 5,208 Other contracts 6,330 (1,455 ) (21,143 ) Total 236,982 328,841 745,692 Foreign exchange gains (losses)—net (4) 91,793 93,577 44,345 Net trading gains (losses) 328,775 422,418 790,037 Notes: (1) Amounts include gains and losses on currency swaps. (2) The net gains (losses) excluded from the assessment of the effectiveness of fair value hedges is included in the above table. (3) Amounts do not include the net gains (losses) of ¥(754) million, ¥(736) million and ¥2,838 million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2018, 2019 and 2020, respectively. The net gains (losses) is recorded in Other noninterest income (expenses). (4) Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.

Fair value (Tables)

Fair value (Tables)	12 Months Ended
	Mar. 31, 2020
Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis, Including Fair Value Option Elected	Assets and liabilities measured at fair value on a recurring basis at March 31, 2019 and 2020, including those for which the MHFG Group has elected the fair value option, are summarized below: 2019 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,829 33 — 1,862 Japanese local government bonds — 134 — 134 U.S. Treasury bonds and federal agency securities 1,069 138 — 1,207 Other foreign government bonds 2,417 553 — 2,970 Agency mortgage-backed securities — 1,041 — 1,041 Residential mortgage-backed securities — — 11 11 Certificates of deposit and commercial paper — 1,047 — 1,047 Corporate bonds and other (2) 36 1,806 1,044 2,886 Equity securities 1,297 — 28 1,325 Trading securities measured at net asset value (3) 631 Derivative financial instruments: Interest rate contracts 36 5,729 21 5,786 Foreign exchange contracts 9 1,927 23 1,959 Equity-related contracts 58 63 4 125 Credit-related contracts — 16 2 18 Other contracts 2 4 10 16 Available-for-sale Japanese government bonds 10,902 995 — 11,897 Japanese local government bonds — 210 — 210 U.S. Treasury bonds and federal agency securities 1,009 — — 1,009 Other foreign government bonds 456 886 — 1,342 Agency mortgage-backed securities — 544 — 544 Residential mortgage-backed securities — 61 40 101 Commercial mortgage-backed securities — — 500 500 Japanese corporate bonds and other debt securities — 1,629 120 1,749 Foreign corporate bonds and other debt securities — 678 103 781 Equity securities Equity securities with readily determinable fair values 3,633 135 — 3,768 Equity securities measured at net asset value (3) 53 Other investments — — 35 35 Total assets measured at fair value on a recurring basis 22,753 17,629 1,941 43,007 Liabilities: Trading securities sold, not yet purchased 2,380 199 1 2,580 Derivative financial instruments: Interest rate contracts 38 5,564 8 5,610 Foreign exchange contracts 11 1,746 1 1,758 Equity-related contracts 82 51 9 142 Credit-related contracts — 16 1 17 Other contracts 1 4 9 14 Long-term debt (4) — 1,778 655 2,433 Total liabilities measured at fair value on a recurring basis 2,512 9,358 684 12,554 2020 Level 1 Level 2 Level 3 Assets/ Liabilities measured at fair value (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,516 22 — 1,538 Japanese local government bonds — 170 — 170 U.S. Treasury bonds and federal agency securities 4,580 461 — 5,041 Other foreign government bonds 1,128 547 — 1,675 Agency mortgage-backed securities — 3,390 — 3,390 Residential mortgage-backed securities — — 10 10 Certificates of deposit and commercial paper — 1,036 — 1,036 Corporate bonds and other (2) 41 1,398 1,115 2,554 Equity securities 1,000 650 30 1,680 Trading securities measured at net asset value (3) 462 Derivative financial instruments: Interest rate contracts 153 7,070 9 7,232 Foreign exchange contracts 9 2,900 17 2,926 Equity-related contracts 169 125 16 310 Credit-related contracts — 22 8 30 Other contracts 3 11 24 38 Available-for-sale Japanese government bonds 11,950 653 — 12,603 Japanese local government bonds — 273 — 273 U.S. Treasury bonds and federal agency securities 935 — — 935 Other foreign government bonds 436 975 — 1,411 Agency mortgage-backed securities — 505 — 505 Residential mortgage-backed securities — 53 31 84 Commercial mortgage-backed securities — — 615 615 Japanese corporate bonds and other debt securities — 1,678 157 1,835 Foreign corporate bonds and other debt securities — 678 174 852 Equity securities Equity securities with readily determinable fair values 2,670 95 — 2,765 Equity securities measured at net asset value (3) 72 Other investments — — 39 39 Total assets measured at fair value on a recurring basis 24,590 22,712 2,245 50,081 Liabilities: Trading securities sold, not yet purchased 1,880 515 — 2,395 Derivative financial instruments: Interest rate contracts 163 6,611 14 6,788 Foreign exchange contracts 8 2,890 1 2,899 Equity-related contracts 186 47 33 266 Credit-related contracts — 19 10 29 Other contracts 6 10 23 39 Long-term debt (4) — 1,916 621 2,537 Total liabilities measured at fair value on a recurring basis 2,243 12,008 702 14,953 Notes: (1) Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option. (2) The amount includes CLO and convertible bonds, which are classified in Level 3 . (3) In accordance with ASC 820, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented for these classes of assets are intended to permit the reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position. The amounts of unfunded commitments related to these investments at March 31, 2019 and 2020 were ¥37 billion and ¥47 billion, respectively. (4) Amounts represent items for which the Group elected the fair value option or for which it applied the practicability exception.
Reconciliation for All Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3)	The following table presents a reconciliation for all assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the fiscal years ended March 31, 2019 and 2020: 2019 April 1, 2018 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments March 31, 2019 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 12 — (2) — — — — — — (1 ) 11 — Corporate bonds and other 1,013 1 (2) — — — 762 (378 ) — (354 ) 1,044 8 Equity securities 23 1 (2) — — — 7 (3 ) — — 28 (1 ) Derivative financial instruments, net (1) Interest rate contracts 21 (11 ) (2) — — — — — — 3 13 (5 ) Foreign exchange contracts 12 15 (2) — — — — — — (5 ) 22 14 Equity-related contracts 4 (15 ) (2) — — — — — — 6 (5 ) 3 Credit-related contracts 1 (2 ) (2) — — — — — — 2 1 1 Other contracts — 1 (2) — — — — — — — 1 1 Available-for-sale Residential mortgage-backed securities 54 — (3) — (4) — — — — — (14 ) 40 — Commercial mortgage-backed securities 441 — (3) 1 (4) — — 144 (72 ) — (14 ) 500 — Japanese corporate bonds and other debt securities 163 37 (3) (33 ) (4) — — 29 (7 ) — (69 ) 120 19 Foreign corporate bonds and other debt securities 80 — (3) (1 ) (4) 61 (42 ) 27 — — (22 ) 103 — Other investments 38 5 (3) — — — 13 (6 ) — (15 ) 35 (2 ) Liabilities: Trading securities sold, not yet purchased 4 1 (2) — — — (35 ) 33 — — 1 — Long-term debt 561 (6 ) (5) 10 (4) 7 — — — 192 (101 ) 655 5 2020 April 1, 2019 Gains (losses) in Earnings Gains (losses) in OCI Transfers into Level 3 Transfers out of Level 3 Purchases Sales Issuances Settle- ments March 31, 2020 Change in unrealized gains (losses) still held (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 11 — (2) — — — — — — (1 ) 10 — Corporate bonds and other 1,044 (52 ) (2) — — — 802 (297 ) — (382 ) 1,115 (52 ) Equity securities 28 (1 ) (2) — — — 6 (2 ) — (1 ) 30 (1 ) Derivative financial instruments, net (1) Interest rate contracts 13 (6 ) (2) — 1 — — — — (13 ) (5 ) (16 ) Foreign exchange contracts 22 (4 ) (2) — — — — — — (2 ) 16 (3 ) Equity-related contracts (5 ) (8 ) (2) — — — — — — (4 ) (17 ) (10 ) Credit-related contracts 1 (2 ) (2) — (1 ) (1 ) — — — 1 (2 ) (1 ) Other contracts 1 2 (2) — — — — — — (2 ) 1 1 Available-for-sale Residential mortgage-backed securities 40 — (3) — (4) — — 3 — — (12 ) 31 — Commercial mortgage-backed securities 500 — (3) 1 (4) — — 201 (77 ) — (10 ) 615 — Japanese corporate bonds and other debt securities 120 2 (3) — (4) — — 106 — — (71 ) 157 — Foreign corporate bonds and other debt securities 103 — (3) (11 ) (4) — — 94 — — (12 ) 174 — Other investments 35 3 (3) — — — 15 — — (14 ) 39 3 Liabilities: Trading securities sold, not yet purchased 1 — (2) — — — (18 ) 17 — — — — Long-term debt 655 53 (5) 17 (4) 77 (8 ) — — 312 (345 ) 621 79 Notes: (1) Total Level 3 derivative exposures have been netted on the table for presentation purposes only. (2) Gains (losses) in Earnings are reported in Trading account gains (losses)—net, Foreign exchange gains (losses)—net or Other noninterest income (expenses). (3) Gains (losses) in Earnings are reported in Investment gains (losses)—net. (4) Gains (losses) in OCI are reported in Other comprehensive income (loss). (5) Gains (losses) in Earnings are reported in Other noninterest income (expenses). (6) Amounts represent total gains or losses recognized in earnings during the period. These gains or losses were attributable to the change in fair value relating to assets and liabilities classified as Level 3 that were still held at March 31, 2019 and 2020.
Quantitative Information about Significant Unobservable Inputs Related to Material Classes of Level 3 Assets and Liabilities	The following table presents information about significant unobservable inputs related to the MHFG Group’s material classes of Level 3 assets and liabilities at March 31, 2019 and 2020: 2019 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Weighted average (5) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage-backed securities 51 Discounted cash flow Price-based Prepayment rate Default rate Recovery rate Discount margin 4%–19% 0%–1% 100%–100% 18bps–170bps 8% 0% 100% 51bps Commercial mortgage-backed securities 500 Discounted cash flow Price-based Discount margin 9bps–161bps 24bps Corporate bonds and other debt securities 1,267 Discounted cash flow Price-based Prepayment rate (1) Default rate (1) Recovery rate (1) Discount margin (1) Discount margin (2) 22%–22% 2%–2% 69%–69% 48bps–1,173bps 4bps–1,063bps 22% 2% 69% 134bps 295bps Derivative financial instruments, net: Interest rate contracts 13 Internal valuation model (3) IR – IR correlation Default rate (4) 23%–100% 0%–63% Foreign exchange contracts 22 Internal valuation model (3) FX – IR correlation FX – FX correlation Default rate (4) 9%–55% 63%–63% 0%–63% Equity-related contracts (5 ) Internal valuation model (3) Equity – IR correlation Equity correlation Equity volatility 25%–25% 40%–100% 5%–36% Credit-related contracts 1 Internal valuation model (3) Default rate Credit correlation 0%–5% 29%–100% Long-term debt 655 Internal valuation model (3) IR – IR correlation 23%–100% FX – IR correlation 9%–55% FX – FX correlation 63%–63% Equity – IR correlation 25%–25% Equity – FX correlation 55%–88% Equity correlation 12%–100% Equity volatility 5%–49% Default rate 0%–4% Credit correlation 20%–100% 2020 Products/Instruments Fair value Principal valuation technique Unobservable inputs Range of input values Weighted average (5) (in billions of yen, except for percentages and basis points) Trading securities and Available-for-sale Residential mortgage- 41 Discounted cash flow Price-based Prepayment rate Default rate Recovery rate Discount margin 4%–16% 0%–1% 100%–100% 5bps–170bps 7% 0% 100% 52bps Commercial mortgage-backed securities 615 Discounted cash flow Price-based Discount margin 7bps–185bps 22bps Corporate bonds and other debt securities 1,446 Discounted cash flow Price-based Prepayment rate (1) Default rate (1) Recovery rate (1) Discount margin (1) Discount margin (2) 13%–21% 0%–2% 10%–70% 61bps–1,160bps 5bps–1,528bps 21% 2% 67% 256bps 58bps Derivative financial instruments, net: Interest rate contracts (5 ) Internal valuation model (3) IR – IR correlation Default rate (4) 23%–100% 0%–63% Foreign exchange contracts 16 Internal valuation model (3) FX – IR correlation FX – FX correlation Default rate (4) -37%–49% 56%–65% 0%–63% Equity-related contracts (17 ) Internal valuation model (3) Equity – IR correlation Equity correlation Equity volatility 25%–25% 0%–100% 13%–157% Credit-related contracts (2 ) Internal valuation model (3) Default rate Credit correlation 0%–15% 30%–100% Long-term debt 621 Internal valuation model (3) IR – IR correlation 23%–100% FX – IR correlation -37%–50% FX – FX correlation 56%–65% Equity – IR correlation 25%–25% Equity – FX correlation -33%–100% Equity correlation 0%–100% Equity volatility 15%–157% Default rate 0%–12% Credit correlation 15%–100% (1) These inputs are mainly used for determining the fair values of securitization products such as CDO, CLO and ABS, other than RMBS and CMBS. (2) This input is mainly used for determining the fair values of Japanese corporate bonds and foreign corporate bonds. (3) Internal valuation model includes discounted cash flow models and the Black-Scholes option pricing model. (4) This input represents the counterparty default rate derived from the MHFG Group’s own internal credit analyses. (5) Weighted averages are calculated by weighting each input by the relative fair value of the respective financial instruments. IR = Interest rate FX = Foreign exchange
Summary of Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis	The following table shows the fair value hierarchy for these items as of March 31, 2019 and 2020: 2019 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 125 — 41 84 177 Loans held-for-sale 3 — 3 — 3 Equity securities (without readily determinable fair values) 1 — — 1 1 Other investments 98 98 — — 104 Premises and equipment—net 9 — 4 5 34 Intangible assets — — — — 1 Total assets measured at fair value on a nonrecurring basis 236 98 48 90 320 2020 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 90 — — 90 136 Loans held-for-sale 26 — 20 6 26 Equity securities (without readily determinable fair values) 2 — — 2 2 Premises and equipment—net 1 — 1 — 12 Other — — — — 3 Good ill — — — — 2 Total assets measured at fair value on a nonrecurring basis 119 — 21 98 181 Note: The fair values may not be current as of the dates indicated, but rather as of the date the fair value change occurred. Accordingly, the carrying values may not equal current fair value.
Carrying Amounts and Fair Values of Certain Financial Instruments, Excluding Financial Instruments Carried at Fair Value on a Recurring Basis and Those outside Scope of ASC 825	The following table shows the carrying amounts and fair values at March 31, 2019 and 2020, of certain financial instruments, excluding financial instruments which are carried at fair value on a recurring basis and those outside the scope of ASC 825 such as equity method investments as defined in ASC 323, “Investments—Equity Method and Joint Ventures” (“ASC 323”) and lease contracts as defined in ASC 842, “Leases” (“ASC 842”): 2019 Carrying amount Estimated fair value Total Level 1 Level 2 Level 3 (in billions of yen) Financial assets: Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions 62,012 62,012 873 61,139 — Investments 1,604 1,609 1,140 469 — Loans, net of allowance for loan losses (Note) 82,382 83,490 — — 83,490 Financial liabilities: Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions 44,918 44,918 24,983 19,935 — Interest-bearing deposits 112,658 112,655 55,542 57,113 — Due to trust accounts 312 312 — 312 — Other short-term borrowings 1,995 1,995 — 1,995 — Long-term debt 9,096 9,178 — 8,336 842 2020 Carrying Estimated fair value Total Level 1 Level 2 Level 3 (in billions of yen) Financial assets: Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions 63,755 63,755 1,318 62,437 — Investments 862 875 493 382 — Loans, net of allowance for loan losses (Note) 86,914 88,124 — — 88,124 Financial liabilities: Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions 51,954 51,954 29,812 22,142 — Interest-bearing deposits 114,653 114,659 58,935 55,724 — Due to trust accounts 250 250 — 250 — Other short-term borrowings 4,914 4,914 — 4,914 — Long-term debt 7,821 7,708 — 6,813 895 Note: Loans, net of allowance for loan losses include items measured at fair value on a nonrecurring basis.

Offsetting of financial asset_2

Offsetting of financial assets and financial liabilities (Tables)	12 Months Ended
	Mar. 31, 2020
Information of Offsetting of Financial Assets and Financial Liabilities	The following table provides information about the offsetting of financial assets and financial liabilities at March 31, 2019 and 2020. The table includes derivatives, repurchase and resale agreements, and securities lending and borrowing transactions that are subject to enforceable master netting arrangements or similar agreements irrespective of whether or not they are offset on the Group’s consolidated balance sheets. Amounts not offset on the balance sheet (3) Gross amounts recognized Gross amounts offset on the balance sheet Net amounts presented on the balance sheet (2) Financial instruments (4) Cash collateral Net amounts (in billions of yen) 2019 Assets (1) Derivatives 7,403 — 7,403 (5,903 ) (528 ) 972 Receivables under resale agreements 12,589 — 12,589 (12,579 ) — 10 Receivables under securities borrowing transactions 1,921 — 1,921 (1,894 ) — 27 Total 21,913 — 21,913 (20,376 ) (528 ) 1,009 Liabilities (1) Derivatives 6,978 — 6,978 (5,766 ) (769 ) 443 Payables under repurchase agreements 14,312 — 14,312 (14,309 ) — 3 Payables under securities lending transactions 932 — 932 (931 ) — 1 Total 22,222 — 22,222 (21,006 ) (769 ) 447 2020 Assets (1) Derivatives 9,819 — 9,819 (7,723 ) (629 ) 1,467 Receivables under resale agreements 17,347 — 17,347 (17,197 ) — 150 Receivables under securities borrowing transactions 1,753 — 1,753 (1,709 ) — 44 Total 28,919 — 28,919 (26,629 ) (629 ) 1,661 Liabilities (1) Derivatives 9,220 — 9,220 (7,519 ) (1,215 ) 486 Payables under repurchase agreements 17,542 — 17,542 (17,191 ) — 351 Payables under securities lending transactions 626 — 626 (623 ) — 3 Total 27,388 — 27,388 (25,333 ) (1,215 ) 840 Notes: (1) Amounts relating to master netting arrangements or similar agreements where the MHFG Group does not have the legal right of set-off over-the-counter OTC-cleared (2) Derivative assets and liabilities are recorded in Trading account assets and Trading account liabilities, respectively. (3) Amounts do not exceed the net amounts presented on the balance sheet and do not include the effect of overcollateralization, where it exists. (4) For derivatives, amounts include derivative assets or liabilities and securities collateral that are eligible for offsetting under enforceable master netting arrangements or similar agreements.

Repurchase agreements and sec_2

Repurchase agreements and securities lending transactions accounted for as secured borrowings (Tables)	12 Months Ended
	Mar. 31, 2020
Gross Amounts of Liabilities by Remaining Contractual Maturity	The following table shows the gross amounts of liabilities associated with repurchase agreements and securities lending transactions, by remaining contractual maturity at March 31, 2019 and 2020: Overnight and continuous Up to 30 days 31-90 Greater than 90 days Total (in billions of yen) 2019 Repurchase agreements 2,596 8,537 2,403 1,104 14,640 Securities lending transactions 1,012 473 — 313 1,798 Total 3,608 9,010 2,403 1,417 16,438 2020 Repurchase agreements 6,357 5,467 4,867 1,280 17,971 Securities lending transactions 877 231 — 316 1,424 Total 7,234 5,698 4,867 1,596 19,395
Gross Amounts of Liabilities by Class of Underlying Collateral	The following table shows the gross amounts of liabilities associated with repurchase agreements and securities lending transactions, by class of underlying collateral at March 31, 2019 and 2020: Repurchase agreements Securities lending transactions (in billions of yen) 2019 Japanese government bonds and Japanese local government bonds 2,118 430 Foreign government bonds and foreign agency mortgage-backed securities 11,613 396 Commercial paper and corporate bonds 223 52 Equity securities 492 902 Other 194 18 Total (Note) 14,640 1,798 2020 Japanese government bonds and Japanese local government bonds 1,790 269 Foreign government bonds and foreign agency mortgage-backed securities 15,218 359 Commercial paper and corporate bonds 273 50 Equity securities 542 730 Other 148 16 Total (Note) 17,971 1,424 Note: Amounts exceeded the gross amounts recognized in Note 28 “Offsetting of financial assets and financial liabilities” by ¥1,194 billion and ¥1,227 billion, at March 31, 2019 and 2020, respectively, which excluded the amounts relating to master netting agreements or similar agreements where the MHFG Group did not have the legal right of set-off

Related Party Transactions (Tab

Related Party Transactions (Table)	12 Months Ended
	Mar. 31, 2020
Related Party Transactions [Abstract]
Summary of financial information of groups equity method investees	Summarized financial information of the MHFG Group’s equity method investees as of March 31, 2019 and 2020, and for each of the three years ended March 31, 2020, is as follows: 2019 2020 (in billions of yen) L 7,954 7,268 Total assets 28,674 27,036 Deposits 10,167 8,665 Total liabilities 26,387 25,014 Total equity 2,287 2,022 Noncontrolling interests 615 11 2018 2019 2020 (in billions of yen) Total interest and dividend income 458 503 586 Total interest expense 153 165 198 Provision (credit) for loan losses 66 84 81 Net interest income after provision (credit) for loan losses 239 254 307 Income before income tax expense 149 229 196 Net income 132 201 150

Business segment information (T

Business segment information (Tables)	12 Months Ended
	Mar. 31, 2020
Reportable Segment Information Derived from Internal Management Reporting Systems, on Basis of Japanese GAAP	The reportable segment information, set forth below, is derived from the internal management reporting systems used by management to measure the performance of the Group’s operating segments. Management measures the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. In addition, the format and information are presented primarily on the basis of Japanese GAAP. Therefore, they are not consistent with the consolidated financial statements prepared in accordance with U.S. GAAP. A reconciliation is provided for the total amount of all business segments’ “Net business profits (losses) + Net gains (losses) related to ETFs and others” with income before income tax expense under U.S. GAAP, and the total amount of all business segments’ “Fixed assets” with the total amount of Premises and equipment-net, MHFG (Consolidated) 2018 (5) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (4) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (1) 725.7 431.0 327.3 387.2 50.0 74.4 1,995.6 General and administrative (2) 724.3 208.4 239.6 204.7 27.6 39.6 1,444.2 Equity in earnings (losses) of equity method investees—net 12.7 1.0 2.3 — 2.9 2.6 21.5 Amortization of goodwill and others 0.4 0.4 0.4 2.3 8.0 2.4 13.9 Others — — — — — (21.0 ) (21.0 ) Net business profits (losses) (3) 13.7 223.2 89.6 180.2 17.3 14.0 538.0 MHFG (Consolidated) 2019 (5) Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (4) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (1) 705.9 473.4 400.3 192.4 49.6 6.1 1,827.7 General and administrative (2) 713.5 205.7 237.9 207.5 27.3 48.7 1,440.6 Equity in earnings (losses) of equity method investees—net 18.1 0.9 7.2 — 1.3 23.7 51.2 Amortization of goodwill and others 0.4 0.4 0.4 2.3 8.0 2.1 13.6 Others — — — — — (16.3 ) (16.3 ) Net business profits (losses) (3) 10.1 268.2 169.2 (17.4 ) 15.6 (37.3 ) 408.4 Fixed assets (6) 499.3 225.8 176.9 92.6 0.1 662.5 1,657.2 MHFG (Consolidated) 2020 Retail & Business Banking Company Corporate & Institutional Company Global Corporate Company Global Markets Company Asset Management Company Others (4) Total (in billions of yen) Gross profits + Net gains (losses) related to ETFs and others (1) 673.6 462.4 417.8 410.1 48.4 60.5 2,072.8 General and administrative expenses (2) 668.5 215.1 249.0 208.9 29.0 41.0 1,411.5 Equity in earnings (losses) of equity method investees—net 11.8 2.0 10.3 — 1.3 5.0 30.4 Amortization of goodwill and others 0.4 0.4 0.4 2.3 7.8 1.9 13.2 Others — — — — — (5.9 ) (5.9 ) Net business profits (losses) (3) 16.5 248.9 178.7 198.9 12.9 16.7 672.6 Fixed assets (6) 503.7 204.1 173.0 91.5 0.1 767.4 1,739.8 Notes: (1) “Gross profits + Net gains (losses) related to ETFs and others” is reported instead of sales reported by general corporations. Gross profits is defined as the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income. Net gains (losses) related to ETFs and others consist of net gains (losses) on ETFs held by MHBK and MHTB on their non-consolidated (2) “General and administrative expenses” excludes non-allocated (3) Net business profits (losses) is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (as defined above) less general and administrative expenses plus equity in earnings (losses) of equity method investees—net and others. Measurement of net business profits (losses) is required for regulatory reporting to the Financial Services Agency of Japan. (4) “Others” includes the following items: • profits and expenses pertaining to consolidated subsidiaries that are not subject to allocation; • consolidating adjustments, including eliminating internal transaction between each segment; • equity in earnings (losses) of equity method investees-net • profits and losses pertaining to derivative transactions that reflect the counterparty risk of the individual parties and other factors in determining fair market value. (5) Beginning on April 1, 2018, new allocation methods for income and expense transactions between each segment and “Others” have been applied. In connection with the use of the new allocation methods, the presentation of “Net business profits” has changed to “Net business profits (losses) + Net gains (losses) related to ETFs and others.” Before the change, “Net gains (losses) related to ETFs and others” were included in “Gross profits” of each segment and eliminated in “Others.” In addition, “Amortization of goodwill and others” has been presented as a new item. Figures for the fiscal year ended March 31, 2018 have been restated for the new allocation methods. These changes more appropriately reflect the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates. (6) “Fixed assets” is presented based on Japanese GAAP and corresponds to the total amount of the following U.S. GAAP accounts: Premises and equipment-net;
Reconciliation of Total Net Business Profits under Internal Management Reporting Systems to Income Before Income Tax Expense on Consolidated Statements of Income	A reconciliation of “Net business profits (losses) + Net gains (losses) related to ETFs and others” for the fiscal years ended March 31, 2018, 2019 and 2020 presented above to income before income tax expense shown on the consolidated statements of income and a reconciliation of “Fixed assets” at March 31, 2019 and 2020 to the total amount of Premises and equipment-net, 2018 2019 2020 (in billions of yen) Net business profits (losses) + Net gains (losses) related to ETFs and others 538.0 408.4 672.6 Adjustment to reconcile management reporting to Japanese GAAP: General and administrative expenses: non-allocated (30.9 ) 23.3 46.3 Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans) (17.0 ) (30.7 ) (183.3 ) Gains on reversal of reserves for possible losses on loans, and others 173.3 11.2 11.6 Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others 191.9 259.9 126.6 Net extraordinary gains (losses) 17.5 (497.9 ) (19.2 ) Others (72.8 ) (57.9 ) (35.9 ) Income before income tax expense under Japanese GAAP 800.0 116.3 618.7 Adjustment to reconcile Japanese GAAP to U.S. GAAP: Derivative financial instruments and hedging activities (110.2 ) 45.3 111.2 Investments 98.1 (273.3 ) (480.9 ) Loans (2.4 ) (11.9 ) (3.0 ) Allowances for loan losses and off-balance-sheet 6.8 (5.8 ) 0.7 Premises and equipment 35.4 303.6 (96.1 ) Land revaluation 3.4 10.2 2.1 Business combinations 15.6 (12.8 ) 6.0 Pension liabilities (4.4 ) (32.2 ) (56.7 ) Consolidation of variable interest entities 2.7 (39.0 ) 39.3 Foreign currency translation 12.1 1.7 17.3 Others (17.8 ) (17.0 ) (5.1 ) Income before income tax expense under U.S. GAAP 839.3 85.1 153.5
Reconciliation of Assets from Segment to Consolidated	2019 2020 (in billions of yen) Fixed assets 1,657.2 1,739.8 U.S. GAAP adjustments (Note) 413.1 887.2 Premises and equipment-net, 2,070.3 2,627.0 Note: The U.S. GAAP adjustments are primarily comprised of GAAP differences mainly from ROU assets related to operating leases not recognized under Japanese GAAP; internally developed software, which was impaired under Japanese GAAP; land, which was revalued under Japanese GAAP; and the consolidation of certain variable interest entities, which are not consolidated under Japanese GAAP. ROU assets are recognized on balance sheets in connection with the adoption of ASU No.2016-02

Foreign activities (Tables)

Foreign activities (Tables)	12 Months Ended
	Mar. 31, 2020
Text Block [Abstract]
Consolidated Income Statement and Total Assets Information by Major Geographic Area	The following table presents consolidated income statement and total assets information by major geographic area. Foreign activities are defined as business transactions that involve customers residing outside of Japan. However, as the MHFG Group’s operations are highly integrated globally, estimates and assumptions have been made for an allocation among the geographic areas. Americas Japan United States of America Others Europe Asia/Oceania excluding Japan, and others Total (in billions of yen) Fiscal year ended March 31, 2018: Total revenue (1) 2,002.4 654.9 64.0 197.4 447.8 3,366.5 Total expenses (2) 1,582.5 478.8 38.5 172.6 254.8 2,527.2 Income before income tax expense 419.9 176.1 25.5 24.8 193.0 839.3 Net income 231.3 152.7 23.7 21.3 172.7 601.7 Total assets at end of fiscal year 142,587.8 28,135.9 4,380.4 11,677.8 17,473.7 204,255.6 Fiscal year ended March 31, 2019: Total revenue (1) 1,705.5 792.1 66.0 249.7 616.5 3,429.8 Total expenses (2) 2,082.6 696.5 46.1 203.2 316.3 3,344.7 Income (loss) before income tax expense (377.1 ) 95.6 19.9 46.5 300.2 85.1 Net income (loss) (331.4 ) 85.3 17.0 34.6 270.2 75.7 Total assets at end of fiscal year 133,443.5 25,913.5 4,824.7 15,322.5 18,107.0 197,611.2 Fiscal year ended March 31, 2020: Total revenue (1) 1,681.0 801.5 95.1 270.4 610.9 3,458.9 Total expenses (2) 2,008.9 679.2 41.5 239.1 336.7 3,305.4 Income (loss) before income tax expense (327.9 ) 122.3 53.6 31.3 274.2 153.5 Net income (loss) (312.8 ) 100.4 51.5 23.6 243.6 106.3 Total assets at end of fiscal year 137,470.4 34,650.4 4,137.3 15,487.0 19,473.7 211,218.8 Notes: (1) Total revenue is comprised of Interest and dividend income and Noninterest income. (2) Total expenses are comprised of Interest expense, Provision (credit) for loan losses and Noninterest expenses.

Mizuho Financial Group, Inc.,_2

Mizuho Financial Group, Inc., parent company (Tables)	12 Months Ended
	Mar. 31, 2020
Condensed Financial Information Disclosure [Abstract]
Condensed Balance Sheets	Condensed balance sheets 2019 2020 (in millions of yen) Assets: Cash and due from banking subsidiaries 99,209 43,016 Interest-bearing deposits in banking subsidiaries 1,158 218 Investments in subsidiaries and affiliated companies: Banking subsidiaries 7,905,018 8,104,662 Non-banking subsidiaries and affiliated companies 1,412,369 1,139,694 Long-term loans receivable from a banking subsidiary 5,110,248 6,539,819 Other 351,951 471,225 Total 14,879,953 16,298,634 Liabilities and shareholders’ equity: Short-term borrowings from a banking subsidiary 945,505 860,000 Long-term debt 5,145,286 6,555,053 Other liabilities 62,643 371,216 Shareholders’ equity 8,726,519 8,512,365 Total 14,879,953 16,298,634
Condensed Statements of Income	Condensed statements of income 2018 2019 2020 (in millions of yen) Income: Dividends from subsidiaries and affiliated companies: Banking subsidiaries 227,057 267,724 23,824 Non-banking 28,987 23,392 12,850 Management fees from subsidiaries 47,945 39,292 38,004 Interest income on loans and discounts 68,869 106,920 123,354 Gains on disposal of premises and equipment — — 10,866 Other income 52,672 9,575 7,088 Total 425,530 446,903 215,986 Expenses: Operating expenses 38,661 40,680 38,951 Interest expense 74,227 110,861 126,516 Other expense 28,123 59,049 25,313 Total 141,011 210,590 190,780 Equity in undistributed net income (loss) of subsidiaries 309,210 (173,142 ) 130,930 Income before income tax expense 593,729 63,171 156,136 Income tax expense (benefit) 16,121 (21,300 ) 5,941 Net income 577,608 84,471 150,195
Condensed Statements of Cash Flows	Condensed statements of cash flows 2018 2019 2020 (in millions of yen) Cash flows from operating activities: Net income 577,608 84,471 150,195 Adjustments and other (302,109 ) 197,193 (92,059 ) Net cash provided by operating activities 275,499 281,664 58,136 Cash flows from investing activities: Proceeds from sales of Equity securities — 139,719 — Net change in loans (1,344,323 ) (1,075,059 ) (1,496,047 ) Purchases of premises and equipment (6,649 ) (11,640 ) (43,406 ) Proceeds from sales of premises and equipment — — 209,657 Net change in other investing activities (4,114 ) (1,310 ) (5,150 ) Net cash used in investing activities (1,355,086 ) (948,290 ) (1,334,946 ) Cash flows from financing activities: Net change in short-term borrowings (70,000 ) (140,000 ) (85,505 ) Proceeds from issuance of long-term debt 1,344,323 1,075,059 1,531,047 Repayment of long-term debt — — (35,000 ) Proceeds from issuance of common stock 3 3 — Purchases of treasury stock (1,611 ) (2,124 ) (1,441 ) Dividends paid (190,382 ) (190,413 ) (190,386 ) Net change in other financing activities 555 437 962 Net cash provided by financing activities 1,082,888 742,962 1,219,677 Effect of exchange rate changes on cash and cash equivalents — 540 — Net increase (decrease) in cash and cash equivalents 3,301 76,876 (57,133 ) Cash and cash equivalents at beginning of fiscal year 20,190 23,491 100,367 Cash and cash equivalents at end of fiscal year 23,491 100,367 43,234

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2020
Minimum
Disclosure of Accounting Policies [Line Items]
Period in which obligors generally determined to be substantially bankrupt, past due (in months)	6 months
Minimum | Software and Software Development Costs
Disclosure of Accounting Policies [Line Items]
Estimated useful life	5 years
Maximum | Software and Software Development Costs
Disclosure of Accounting Policies [Line Items]
Estimated useful life	10 years
Impaired loans | Minimum
Disclosure of Accounting Policies [Line Items]
Number of days past due	90 days
Customer Relationships [Member] | Shinko Securities Company Limited
Disclosure of Accounting Policies [Line Items]
Weighted-average amortization period	16 years
Customer Relationships [Member] | Asset Management Company
Disclosure of Accounting Policies [Line Items]
Weighted-average amortization period	16 years 10 months 24 days

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies (Useful Lives of Premises and Equipment) (Detail)	12 Months Ended
	Mar. 31, 2020
Minimum | Buildings
Disclosure of Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Years	3 years
Minimum | Equipment and furniture
Disclosure of Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Years	2 years
Maximum | Buildings
Disclosure of Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Years	50 years
Maximum | Equipment and furniture
Disclosure of Basis of Presentation and Summary of Significant Accounting Policies [Line Items]
Years	20 years

Issued accounting pronounceme_2

Issued accounting pronouncements - Additional Information (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019	Apr. 01, 2018	Mar. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principles, net of tax				¥ 5,000
Operating assets, right of use assets	[1],[2]	¥ 613,068
Operating assets, lease liabilities	[1],[2]	¥ 627,250
Operating Lease, Liability, Statement of Financial Position [Extensible List]		us-gaap:OperatingLeaseLiability
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principles, net of tax			¥ 1,052	10,000	¥ 1,540,317
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating assets, right of use assets		¥ 600,000
Operating assets, lease liabilities		¥ 600,000
Operating Lease, Liability, Statement of Financial Position [Extensible List]		us-gaap:OperatingLeaseLiability
ASU No.2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principles, net of tax				1,545,000
ASU No.2016-01 | Retained Earnings | Equity Method Investments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principles, net of tax				¥ 1,530,000
[1]	ROU assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets.
[2]	ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 on April 1, 2019. See Note 1 “Basis of presentation and summary of significant accounting policies” and Note 2 “Issued accounting pronouncements” for further information.

Investments - Amortized Cost, G

Investments - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale and Held-to-Maturity Securities (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		¥ 19,132,999	¥ 18,094,439
Gross unrealized gains, available-for-sale securities		40,504	45,923
Gross unrealized losses, available-for-sale securities		60,551	6,446
Fair value, available-for-sale securities		19,112,952	18,133,916
Amortized cost, held-to-maturity securities		862,031	1,604,104
Gross unrealized gains, held-to-maturity securities		14,602	19,907
Gross unrealized losses, held-to-maturity securities		1,303	14,423
Total		875,330	1,609,588
Debt securities | Japanese government bonds
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		12,651,677	11,888,510
Gross unrealized gains, available-for-sale securities		1,319	11,259
Gross unrealized losses, available-for-sale securities		50,224	2,998
Fair value, available-for-sale securities		12,602,772	11,896,771
Amortized cost, held-to-maturity securities		479,936	1,119,899
Gross unrealized gains, held-to-maturity securities		13,357	19,907
Gross unrealized losses, held-to-maturity securities
Total		493,293	1,139,806
Debt securities | Japanese local government bonds
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		272,412	208,308
Gross unrealized gains, available-for-sale securities		649	1,671
Gross unrealized losses, available-for-sale securities		494	87
Fair value, available-for-sale securities		272,567	209,892
Debt securities | U.S. Treasury bonds and federal agency securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		927,172	1,008,903
Gross unrealized gains, available-for-sale securities		7,733	644
Gross unrealized losses, available-for-sale securities		0	231
Fair value, available-for-sale securities		934,905	1,009,316
Debt securities | Other foreign government bonds
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		1,408,009	1,341,564
Gross unrealized gains, available-for-sale securities		3,273	758
Gross unrealized losses, available-for-sale securities		202	455
Fair value, available-for-sale securities		1,411,080	1,341,867
Debt securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities	[1]	494,958	530,540
Gross unrealized gains, available-for-sale securities	[1]	10,490	14,524
Gross unrealized losses, available-for-sale securities	[1],[2]	434	593
Fair value, available-for-sale securities	[1]	505,014	544,471
Amortized cost, held-to-maturity securities	[3]	382,095	484,205
Gross unrealized gains, held-to-maturity securities	[3]	1,245
Gross unrealized losses, held-to-maturity securities	[3]	1,303	14,423
Total	[3]	382,037	469,782
Debt securities | Residential mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		83,077	99,904
Gross unrealized gains, available-for-sale securities		1,405	1,420
Gross unrealized losses, available-for-sale securities		151	191
Fair value, available-for-sale securities		84,331	101,133
Debt securities | Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		609,559	495,313
Gross unrealized gains, available-for-sale securities		5,551	4,914
Gross unrealized losses, available-for-sale securities		106	104
Fair value, available-for-sale securities		615,004	500,123
Debt securities | Japanese corporate bonds and other debt securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		1,836,540	1,743,309
Gross unrealized gains, available-for-sale securities		7,489	7,686
Gross unrealized losses, available-for-sale securities		8,772	1,561
Fair value, available-for-sale securities		1,835,257	1,749,434
Debt securities | Foreign corporate bonds and other debt securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities	[4]	849,595	778,088
Gross unrealized gains, available-for-sale securities	[4]	2,595	3,047
Gross unrealized losses, available-for-sale securities	[4]	168	226
Fair value, available-for-sale securities	[4]	¥ 852,022	¥ 780,909
[1]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥517,330 million and ¥27,141 million, respectively, at March 31, 2019, and ¥504,953 million and ¥61 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government.
[2]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥11,107 million and ¥27,065 million, respectively, at March 31, 2019, and ¥40,417 million and ¥0 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government.
[3]	All Agency mortgage-backed securities presented in this line are Ginnie Mae securities.
[4]	Other debt securities presented in this line primarily consist of Foreign negotiable certificates of deposit (“NCDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥246,503 million at March 31, 2019, and ¥271,387 million at March 31, 2020.

Investments - Amortized Cost,_2

Investments - Amortized Cost, Gross Unrealized Gains and Losses, and Fair Value of Available-for-Sale and Held-to-Maturity Securities (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		¥ 19,112,952	¥ 18,133,916
Debt securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities	[1]	505,014	544,471
Debt securities | Japanese agency mortgage-backed securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		504,953	517,330
Debt securities | Foreign agency mortgage-backed securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		61	27,141
Foreign government and corporate debt securities | Negotiable certificates of deposits, asset- backed securities and collateral loan obligations
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		¥ 271,387	¥ 246,503
[1]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥517,330 million and ¥27,141 million, respectively, at March 31, 2019, and ¥504,953 million and ¥61 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government.

Investments (Amortized Cost and

Investments (Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities by Contractual Maturity) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		¥ 8,289,207
Due after one year through five years, amortized cost		6,972,532
Due after five years through ten years,amortized cost		2,915,246
Due after ten years, amortized cost		956,014
Total		19,132,999
Due in one year or less, amortized cost
Due after one year through five years, amortized cost		479,936
Due after five years through ten years, amortized cost
Due after ten years, amortized cost		382,095
Amortized cost, held-to-maturity securities		862,031	¥ 1,604,104
Due in one year or less, fair value		8,299,027
Due after one year through five years, fair value		6,960,589
Due after five years through ten years, fair value		2,887,407
Due after ten years, fair value		965,929
Total		19,112,952
Due in one year or less, fair value
Due after one year through five years, fair value		493,293
Due after five years through ten years, fair value
Due after ten years, fair value		382,037
Total		875,330	1,609,588
Debt securities | Japanese government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		5,872,058
Due after one year through five years, amortized cost		4,980,539
Due after five years through ten years,amortized cost		1,753,300
Due after ten years, amortized cost		45,780
Total		12,651,677
Due in one year or less, amortized cost
Due after one year through five years, amortized cost		479,936
Due after five years through ten years, amortized cost
Due after ten years, amortized cost
Amortized cost, held-to-maturity securities		479,936	1,119,899
Due in one year or less, fair value		5,872,485
Due after one year through five years, fair value		4,963,282
Due after five years through ten years, fair value		1,722,090
Due after ten years, fair value		44,915
Total		12,602,772
Due in one year or less, fair value
Due after one year through five years, fair value		493,293
Due after five years through ten years, fair value
Due after ten years, fair value
Total		493,293	1,139,806
Debt securities | Japanese local government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		11,530
Due after one year through five years, amortized cost		171,825
Due after five years through ten years,amortized cost		84,528
Due after ten years, amortized cost		4,529
Total		272,412
Due in one year or less, fair value		11,537
Due after one year through five years, fair value		172,052
Due after five years through ten years, fair value		84,443
Due after ten years, fair value		4,535
Total		272,567
Debt securities | U.S. Treasury bonds and federal agency securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		883,432
Due after one year through five years, amortized cost		43,740
Due after five years through ten years,amortized cost
Due after ten years, amortized cost
Total		927,172
Due in one year or less, fair value		890,367
Due after one year through five years, fair value		44,538
Due after five years through ten years, fair value
Due after ten years, fair value
Total		934,905
Debt securities | Other foreign government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		1,029,641
Due after one year through five years, amortized cost		378,368
Due after five years through ten years,amortized cost
Due after ten years, amortized cost
Total		1,408,009
Due in one year or less, fair value		1,031,189
Due after one year through five years, fair value		379,891
Due after five years through ten years, fair value
Due after ten years, fair value
Total		1,411,080
Debt securities | Agency mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost
Due after one year through five years, amortized cost
Due after five years through ten years,amortized cost
Due after ten years, amortized cost		494,958
Total		494,958
Due in one year or less, amortized cost
Due after one year through five years, amortized cost
Due after five years through ten years, amortized cost
Due after ten years, amortized cost		382,095
Amortized cost, held-to-maturity securities	[1]	382,095	484,205
Due in one year or less, fair value
Due after one year through five years, fair value
Due after five years through ten years, fair value
Due after ten years, fair value		505,014
Total		505,014
Due in one year or less, fair value
Due after one year through five years, fair value
Due after five years through ten years, fair value
Due after ten years, fair value		382,037
Total	[1]	382,037	¥ 469,782
Debt securities | Residential mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost
Due after one year through five years, amortized cost
Due after five years through ten years,amortized cost
Due after ten years, amortized cost		83,077
Total		83,077
Due in one year or less, fair value
Due after one year through five years, fair value
Due after five years through ten years, fair value
Due after ten years, fair value		84,331
Total		84,331
Debt securities | Commercial mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		16,372
Due after one year through five years, amortized cost		202,044
Due after five years through ten years,amortized cost		390,343
Due after ten years, amortized cost		800
Total		609,559
Due in one year or less, fair value		16,396
Due after one year through five years, fair value		203,233
Due after five years through ten years, fair value		394,561
Due after ten years, fair value		814
Total		615,004
Debt securities | Japanese corporate bonds and other debt securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		98,532
Due after one year through five years, amortized cost		868,704
Due after five years through ten years,amortized cost		545,320
Due after ten years, amortized cost		323,984
Total		1,836,540
Due in one year or less, fair value		98,589
Due after one year through five years, fair value		868,675
Due after five years through ten years, fair value		544,559
Due after ten years, fair value		323,434
Total		1,835,257
Debt securities | Foreign corporate bonds and other debt securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		377,642
Due after one year through five years, amortized cost		327,312
Due after five years through ten years,amortized cost		141,755
Due after ten years, amortized cost		2,886
Total		849,595
Due in one year or less, fair value		378,464
Due after one year through five years, fair value		328,918
Due after five years through ten years, fair value		141,754
Due after ten years, fair value		2,886
Total		¥ 852,022
[1]	All Agency mortgage-backed securities presented in this line are Ginnie Mae securities.

Investments - Additional Inform

Investments - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Gain (Loss) on Securities [Line Items]
Equity method Investments, carrying value	¥ 404,513	¥ 354,268
Held-to-maturity Securities
Gain (Loss) on Securities [Line Items]
Impairment loss on securities	¥ 0
Orient Corporation
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	49.00%
Chiba Kogya Bank LTD [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	16.89%
Joint Stock Commercial Bank Foreign Trade of Vietnam [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	15.00%
Mizuho Leasing Company LTD [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	23.52%
Matthew International Capital Management LLC [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	16.25%
JTC Holdings LTD [Member]
Gain (Loss) on Securities [Line Items]
Percentage of proportionate share to the total outstanding common stock	27.00%
Equity securities (marketable)
Gain (Loss) on Securities [Line Items]
Equity method Investments, carrying value	¥ 213,243	201,034
Equity method Investments, aggregated market values	¥ 287,488	¥ 308,137

Investments - Gross Unrealized

Investments - Gross Unrealized Losses and Fair Value of Available-for-Sale and Held-to-Maturity Securities, Aggregated by Length of Time that Individual Securities Have Been in a Continuous Unrealized Loss Position (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		¥ 11,576,157	¥ 3,809,946
Less than 12 months Gross unrealized losses, available-for-sale securities		49,870	3,137
12 months or more Fair value, available-for-sale securities		954,032	2,010,191
12 months or more Gross unrealized losses, available-for-sale securities		10,681	3,309
Total Fair value, available-for-sale securities		12,530,189	5,820,137
Total Gross unrealized losses, available-for-sale securities		60,551	6,446
Less than 12 months, Fair value, held-to-maturity securities		0	0
Less than 12 months Gross unrealized losses, held-to-maturity securities		0	0
12 months or more Fair value, held-to-maturity securities		191,244	469,782
12 months or more Gross unrealized losses, held-to-maturity securities		1,303	14,423
Total Fair value, held-to-maturity securities		191,244	469,782
Total Gross unrealized losses, held-to-maturity securities		1,303	14,423
Debt securities | Japanese government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		10,339,320	2,296,536
Less than 12 months Gross unrealized losses, available-for-sale securities		43,204	1,441
12 months or more Fair value, available-for-sale securities		283,561	1,332,688
12 months or more Gross unrealized losses, available-for-sale securities		7,020	1,557
Total Fair value, available-for-sale securities		10,622,881	3,629,224
Total Gross unrealized losses, available-for-sale securities		50,224	2,998
Total Gross unrealized losses, held-to-maturity securities
Debt securities | Japanese local government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		162,665	9,752
Less than 12 months Gross unrealized losses, available-for-sale securities		418	32
12 months or more Fair value, available-for-sale securities		34,114	38,873
12 months or more Gross unrealized losses, available-for-sale securities		76	55
Total Fair value, available-for-sale securities		196,779	48,625
Total Gross unrealized losses, available-for-sale securities		494	87
Debt securities | U.S. Treasury bonds and federal agency securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		0	506,176
Less than 12 months Gross unrealized losses, available-for-sale securities		0	231
12 months or more Fair value, available-for-sale securities		0	0
12 months or more Gross unrealized losses, available-for-sale securities		0	0
Total Fair value, available-for-sale securities		0	506,176
Total Gross unrealized losses, available-for-sale securities		0	231
Debt securities | Other foreign government bonds
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		196,990	438,771
Less than 12 months Gross unrealized losses, available-for-sale securities		202	321
12 months or more Fair value, available-for-sale securities		0	26,782
12 months or more Gross unrealized losses, available-for-sale securities		0	134
Total Fair value, available-for-sale securities		196,990	465,553
Total Gross unrealized losses, available-for-sale securities		202	455
Debt securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities	[1]	30,913	466
Less than 12 months Gross unrealized losses, available-for-sale securities	[1]	227	2
12 months or more Fair value, available-for-sale securities	[1]	9,504	37,706
12 months or more Gross unrealized losses, available-for-sale securities	[1]	207	591
Total Fair value, available-for-sale securities	[1]	40,417	38,172
Total Gross unrealized losses, available-for-sale securities	[1],[2]	434	593
Less than 12 months, Fair value, held-to-maturity securities		0	0	[3]
Less than 12 months Gross unrealized losses, held-to-maturity securities		0	0	[3]
12 months or more Fair value, held-to-maturity securities		191,244	469,782	[3]
12 months or more Gross unrealized losses, held-to-maturity securities		1,303	14,423	[3]
Total Fair value, held-to-maturity securities		191,244	469,782	[3]
Total Gross unrealized losses, held-to-maturity securities	[3]	1,303	14,423
Debt securities | Residential mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		9,524	0
Less than 12 months Gross unrealized losses, available-for-sale securities		62	0
12 months or more Fair value, available-for-sale securities		5,450	16,729
12 months or more Gross unrealized losses, available-for-sale securities		89	191
Total Fair value, available-for-sale securities		14,974	16,729
Total Gross unrealized losses, available-for-sale securities		151	191
Debt securities | Commercial mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		15,115	11,256
Less than 12 months Gross unrealized losses, available-for-sale securities		85	44
12 months or more Fair value, available-for-sale securities		7,478	36,760
12 months or more Gross unrealized losses, available-for-sale securities		21	60
Total Fair value, available-for-sale securities		22,593	48,016
Total Gross unrealized losses, available-for-sale securities		106	104
Debt securities | Japanese corporate bonds and other debt securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		669,572	417,825
Less than 12 months Gross unrealized losses, available-for-sale securities		5,507	924
12 months or more Fair value, available-for-sale securities		608,361	440,937
12 months or more Gross unrealized losses, available-for-sale securities		3,265	637
Total Fair value, available-for-sale securities		1,277,933	858,762
Total Gross unrealized losses, available-for-sale securities		8,772	1,561
Debt securities | Foreign corporate bonds and other debt securities
Gain (Loss) on Securities [Line Items]
Less than 12 months, Fair value, available-for-sale securities		152,058	129,164
Less than 12 months Gross unrealized losses, available-for-sale securities		165	142
12 months or more Fair value, available-for-sale securities		5,564	79,716
12 months or more Gross unrealized losses, available-for-sale securities		3	84
Total Fair value, available-for-sale securities		157,622	208,880
Total Gross unrealized losses, available-for-sale securities	[4]	¥ 168	¥ 226
[1]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥11,107 million and ¥27,065 million, respectively, at March 31, 2019, and ¥40,417 million and ¥0 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government.
[2]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥517,330 million and ¥27,141 million, respectively, at March 31, 2019, and ¥504,953 million and ¥61 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government.
[3]	All Agency mortgage-backed securities presented in this line are Ginnie Mae securities.
[4]	Other debt securities presented in this line primarily consist of Foreign negotiable certificates of deposit (“NCDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥246,503 million at March 31, 2019, and ¥271,387 million at March 31, 2020.

Investments - Gross Unrealize_2

Investments - Gross Unrealized Losses and Fair Value of Available-for-Sale and Held-to-Maturity Securities, Aggregated by Length of Time that Individual Securities Have Been in a Continuous Unrealized Loss Position (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities		¥ 12,530,189	¥ 5,820,137
Debt securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities	[1]	40,417	38,172
Debt securities | Japanese agency mortgage-backed securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities		40,417	11,107
Debt securities | Foreign agency mortgage-backed securities | Agency mortgage-backed securities
Gain (Loss) on Securities [Line Items]
Fair value, available-for-sale securities		¥ 0	¥ 27,065
[1]	Agency mortgage-backed securities presented in this line consist of Japanese and Foreign agency mortgage-backed securities, of which the fair values were ¥11,107 million and ¥27,065 million, respectively, at March 31, 2019, and ¥40,417 million and ¥0 million, respectively, at March 31, 2020. All Japanese agency mortgage-backed securities are issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. Foreign agency mortgage-backed securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government.

Investments - Realized Gains an

Investments - Realized Gains and Losses on Sales of Available-for-Sale Securities (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	[1]	Mar. 31, 2019	[1]	Mar. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Gross realized gains	¥ 41,903		¥ 23,777		¥ 314,948
Gross realized losses	(13,398)		(26,299)		(41,044)
Net realized gains (losses) on sales of available-for-sale securities	¥ 28,505		¥ (2,522)		¥ 273,904
[1]	Effective April 1, 2018, the available-for-sale category was eliminated for equity securities, and gains and losses on these securities are not included for the fiscal years ended March 31, 2019 and 2020 columns in this table. See Note 2 “Issued accounting pronouncements” for further details.

Investments - Summary of Detail

Investments - Summary of Details of Net Gains and Losses on Equity Securities (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Gain (Loss) on Securities [Line Items]
Net gains (losses) recognized during the period on equity securities	[1]	¥ (557,391)	¥ (155,947)	¥ 289,400
Less: Net gains (losses) recognized during the period on equity securities sold during the period		1,710	34,034
Unrealized gains (losses) recognized during the reporting period on equity securities still held at the reporting period		¥ (559,101)	¥ (189,981)
[1]	These amounts are revenues from contracts that do not meet the scope of ASC 606.

Investments - Summary of Equity

Investments - Summary of Equity Securities Without Readily Determinable Fair Values (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Equity Securities without Readily Determinable Fair Value [Line Items]
Carrying amounts at the end of the period	¥ 419,775	¥ 212,270
Downward adjustments and impairments	2,435	1,413
Upward adjustments	¥ 9,128	¥ 2,373

Investments - Summary of Downwa

Investments - Summary of Downward Adjustments and Impairments and Upward Adjustments (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Equity Securities without Readily Determinable Fair Value [Line Items]
Downward adjustments and impairments	¥ 1,272	¥ 1,413
Upward adjustments	¥ 6,928	¥ 2,373

Investments - Summary of Compos

Investments - Summary of Composition of Other Investments (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Schedule of Investments [Line Items]
Equity method investments	¥ 404,513	¥ 354,268
Investments held by consolidated investment companies	39,438	35,472
Total	¥ 443,951	¥ 389,740

Loans - Loans Outstanding by Do

Loans - Loans Outstanding by Domicile and Industry of Borrower (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020		Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[1]	¥ 87,677,169		¥ 82,952,090
Less: Unearned income and deferred loan fees-net		149,081		152,147
Loans outstanding		87,528,088		82,799,943
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		56,030,511		54,409,144
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,731,028		9,553,854
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,603,433		8,950,577
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,992,511		5,016,971
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,219,727		5,159,356
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,832,884		3,693,491
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,634,442		4,345,589
Domestic | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,198,805		2,358,904
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,389,347		5,472,597	[2]
Domestic | Mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		8,567,099		8,950,216
Domestic | Other individual loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		861,235		907,589
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		31,646,658	[3]	28,542,946
Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		10,475,277		9,086,721
Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		317,284		296,872
Foreign | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		20,818,709		19,126,182
Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		¥ 35,388		¥ 33,171
[1]	Amounts represent loan balances before deducting unearned income and deferred loan fees.
[2]	Other industries of domestic includes trade receivables and lease receivables of consolidated VIEs.
[3]	Impaired loans to foreign borrowers decreased by ¥15,960 million due mainly to the sale of certain loans, partly offset by deterioration of credit status of certain other borrowers.

Loans - Additional Information

Loans - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net losses on sales of loans	¥ 1,036	¥ 2,018	¥ 87
Impaired Financing Receivables with No Related Allowance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans partially charged off	¥ 20,378	¥ 25,097

Loans - Credit Quality Informat

Loans - Credit Quality Information of Loans Based on MHFG Group's Internal Rating System (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020		Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[1]	¥ 87,677,169		¥ 82,952,090
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		56,030,511		54,409,144
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,731,028		9,553,854
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,603,433		8,950,577
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,992,511		5,016,971
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,219,727		5,159,356
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,832,884		3,693,491
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,634,442		4,345,589
Domestic | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,198,805		2,358,904
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,389,347		5,472,597	[2]
Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,428,334		9,857,805
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		31,646,658	[3]	28,542,946
Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		10,475,277		9,086,721
Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		317,284		296,872
Foreign | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		20,818,709		19,126,182
Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		35,388		33,171
Financing Receivables Not Impaired | Normal obligors | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		69,881,479		65,286,588
Financing Receivables Not Impaired | Normal obligors | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	9,911,109		10,372,030
Financing Receivables Not Impaired | Normal obligors | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	5,631,756		5,456,385
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		42,025,243		40,303,480
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,007,095		9,205,542
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		8,849,784		8,182,062
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,600,528		4,665,709
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,766,460		4,682,630
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,692,025		3,543,952
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,595,441		4,304,483
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,198,796		2,358,899
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,106,282		3,126,217	[2]
Financing Receivables Not Impaired | Normal obligors | Domestic | Corporate | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		208,832		233,986
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	9,900,419		10,362,135
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	62,921		69,080
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	473,339		505,142
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	159,657		165,643
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	145,568		161,392
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	65,535		71,934
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	1,593		1,534
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	9		5
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[4]	2,684		2,450
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	8,989,113		9,384,955
Financing Receivables Not Impaired | Normal obligors | Domestic | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	2,344,929		2,455,064
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	17,445		19,805
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	12,710		15,920
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	2,943		3,281
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	17,156		26,881
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	395		934
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	347		72
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[5]	2,230,748		2,323,197
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	63,185		64,974
Financing Receivables Not Impaired | Normal obligors | Foreign | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		27,856,236	[3]	24,983,108
Financing Receivables Not Impaired | Normal obligors | Foreign | Corporate | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,745,247		8,583,432
Financing Receivables Not Impaired | Normal obligors | Foreign | Corporate | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		303,393		296,870
Financing Receivables Not Impaired | Normal obligors | Foreign | Corporate | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		17,806,263		16,101,326
Financing Receivables Not Impaired | Normal obligors | Foreign | Corporate | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		1,333		1,480
Financing Receivables Not Impaired | Normal obligors | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		10,690	[3]	9,895	[4]
Financing Receivables Not Impaired | Normal obligors | Foreign | Retail | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	284		182
Financing Receivables Not Impaired | Normal obligors | Foreign | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	10,406		9,713
Financing Receivables Not Impaired | Normal obligors | Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,286,827	[3]	3,001,321	[5]
Financing Receivables Not Impaired | Normal obligors | Foreign | Other | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	726,823		492,831
Financing Receivables Not Impaired | Normal obligors | Foreign | Other | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	13,129
Financing Receivables Not Impaired | Normal obligors | Foreign | Other | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	2,526,317		2,488,800
Financing Receivables Not Impaired | Normal obligors | Foreign | Other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	20,558		19,690
Financing Receivables Not Impaired | Watch obligors | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	1,354,018		999,405
Financing Receivables Not Impaired | Watch obligors | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	125,975		145,546
Financing Receivables Not Impaired | Watch obligors | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		56,628		46,004	[5],[6]
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	1,034,092		641,554
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	475,983		141,202
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	201,384		186,753
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	131,783		90,178
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	119,778		127,695
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	44,250		37,993
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	24,686		28,881
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[6]	15,238		7,725
Financing Receivables Not Impaired | Watch obligors | Domestic | Corporate | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	20,990		21,127
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	125,960		145,546
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	7,474		8,278
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	10,928		14,490
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	16,602		18,586
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	22,363		25,553
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	7,664		7,472
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	429		319
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	372		421	[4],[6]
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	60,128		70,427
Financing Receivables Not Impaired | Watch obligors | Domestic | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5],[6]	19,192		6,721
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5],[6]	684		1,303
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5],[6]			25
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5],[6]	15		1
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5],[6]	873		591
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5],[6]	303
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[5]	15,038		3,633	[6]
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5],[6]	2,279		1,168
Financing Receivables Not Impaired | Watch obligors | Foreign | Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		319,926	[3]	357,851	[6]
Financing Receivables Not Impaired | Watch obligors | Foreign | Corporate | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	3,207		10,458
Financing Receivables Not Impaired | Watch obligors | Foreign | Corporate | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	762
Financing Receivables Not Impaired | Watch obligors | Foreign | Corporate | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	314,273		347,060
Financing Receivables Not Impaired | Watch obligors | Foreign | Corporate | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[6]	1,684		333
Financing Receivables Not Impaired | Watch obligors | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	15
Financing Receivables Not Impaired | Watch obligors | Foreign | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[6]	15
Financing Receivables Not Impaired | Watch obligors | Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		37,436	[3]	39,283	[5],[6]
Financing Receivables Not Impaired | Watch obligors | Foreign | Other | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		36,593		38,404	[5],[6]
Financing Receivables Not Impaired | Watch obligors | Foreign | Other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		843		879	[5],[6]
Financing Receivables Impaired | Impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		716,204		646,132
Financing Receivables Impaired | Impaired loans | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		580,676		494,644
Financing Receivables Impaired | Impaired loans | Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		159,426		108,644
Financing Receivables Impaired | Impaired loans | Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		55,288		46,185
Financing Receivables Impaired | Impaired loans | Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		80,983		73,573
Financing Receivables Impaired | Impaired loans | Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		147,529		134,614
Financing Receivables Impaired | Impaired loans | Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		22,712		31,206
Financing Receivables Impaired | Impaired loans | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		11,946		10,300
Financing Receivables Impaired | Impaired loans | Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		18,985		8,954	[2]
Financing Receivables Impaired | Impaired loans | Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		83,807		81,168
Financing Receivables Impaired | Impaired loans | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		135,528	[3]	151,488
Financing Receivables Impaired | Impaired loans | Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding				2
Financing Receivables Impaired | Impaired loans | Foreign | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		134,979		150,410
Financing Receivables Impaired | Impaired loans | Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		¥ 549		¥ 1,076
[1]	Amounts represent loan balances before deducting unearned income and deferred loan fees.
[2]	Other industries of domestic includes trade receivables and lease receivables of consolidated VIEs.
[3]	Impaired loans to foreign borrowers decreased by ¥15,960 million due mainly to the sale of certain loans, partly offset by deterioration of credit status of certain other borrowers.
[4]	The primary component of the retail portfolio segment is mortgage loans to individuals which obligor category is classified based on past due status. The trigger to reclassify obligors from normal obligors to watch obligors excluding special attention obligors is when the past due status is more than 30 days.
[5]	Non-impaired loans held by subsidiaries other than MHBK and MHTB constitute other, since their portfolio segments are not identical to those of MHBK and MHTB.
[6]	Special attention obligors are watch obligors with debt in TDR or 90 days or more delinquent debt. Loans to such obligors are considered impaired.

Loans - Credit Quality Inform_2

Loans - Credit Quality Information of Loans Based on MHFG Group's Internal Rating System (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Mar. 31, 2020USD ($)
Financing Receivables Impaired [Member] | Foreign [Member] | Sale Of Impaired Loans And Credit Losses [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Decrease in impaired loans	$ 15,960

Loans (Impaired Loans Informati

Loans (Impaired Loans Information) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	¥ 596,000	¥ 529,048
Recorded investment not requiring an allowance for loan losses	[1],[2]	120,204	117,084
Total	[2]	716,204	646,132
Unpaid principal balance		765,048	694,995
Related allowance	[3]	231,026	169,245
Average recorded investment		663,486	609,745
Interest income recognized	[4]	10,694	8,157
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	500,711	409,969
Recorded investment not requiring an allowance for loan losses		79,965	84,675
Total	[2]	580,676	494,644
Unpaid principal balance		613,836	530,011
Related allowance	[3]	163,791	121,900
Average recorded investment		540,173	496,186
Interest income recognized	[4]	7,662	6,639
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	152,865	103,039
Recorded investment not requiring an allowance for loan losses	[1],[2]	6,561	5,605
Total	[2]	159,426	108,644
Unpaid principal balance		162,742	111,533
Related allowance	[3]	62,879	39,301
Average recorded investment		139,123	122,764
Interest income recognized	[4]	2,292	1,404
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	47,413	36,873
Recorded investment not requiring an allowance for loan losses	[1],[2]	7,875	9,312
Total	[2]	55,288	46,185
Unpaid principal balance		62,064	51,158
Related allowance	[3]	8,366	4,661
Average recorded investment		50,343	42,224
Interest income recognized	[4]	593	487
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	71,358	64,021
Recorded investment not requiring an allowance for loan losses	[1],[2]	9,625	9,552
Total	[2]	80,983	73,573
Unpaid principal balance		85,565	79,736
Related allowance	[3]	20,117	16,311
Average recorded investment		78,583	67,679
Interest income recognized	[4]	973	1,058
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	139,338	124,911
Recorded investment not requiring an allowance for loan losses	[1],[2]	8,191	9,703
Total	[2]	147,529	134,614
Unpaid principal balance		158,933	147,665
Related allowance	[3]	48,582	38,763
Average recorded investment		139,042	130,860
Interest income recognized	[4]	1,845	1,814
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	20,203	28,297
Recorded investment not requiring an allowance for loan losses	[1],[2]	2,509	2,909
Total	[2]	22,712	31,206
Unpaid principal balance		23,555	32,139
Related allowance	[3]	7,318	13,146
Average recorded investment		25,549	29,864
Interest income recognized	[4]	383	412
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	8,193	6,473
Recorded investment not requiring an allowance for loan losses	[1],[2]	3,753	3,827
Total	[2]	11,946	10,300
Unpaid principal balance		11,946	10,300
Related allowance	[3]	1,541	1,327
Average recorded investment		10,565	10,671
Interest income recognized	[4]	129	109
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	18,709	8,867
Recorded investment not requiring an allowance for loan losses	[1],[2]	276	87
Total	[2]	18,985	8,954
Unpaid principal balance		20,716	9,149
Related allowance	[3]	8,606	5,761
Average recorded investment		14,512	6,042
Interest income recognized	[4]	194	29
Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	42,632	37,488
Recorded investment not requiring an allowance for loan losses	[1],[2]	41,175	43,680
Total	[2]	83,807	81,168
Unpaid principal balance		88,315	88,331
Related allowance	[3]	6,382	2,630
Average recorded investment		82,456	86,082
Interest income recognized	[4]	1,253	1,326
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1],[5]	95,289	119,079
Recorded investment not requiring an allowance for loan losses	[1],[2],[5]	40,239	32,409
Total	[1],[5]	135,528	151,488
Unpaid principal balance		151,212	164,984
Related allowance	[3],[5]	67,235	47,345
Average recorded investment		123,313	113,559
Interest income recognized	[4],[5]	¥ 3,032	¥ 1,518
[1]	Amounts represent the outstanding balances of nonaccrual loans. The MHFG Group’s policy for placing loans in nonaccrual status corresponds to the Group’s definition of impaired loans.
[2]	These impaired loans do not require an allowance for loan losses because the MHFG Group has sufficient collateral to cover probable loan losses.
[3]	The allowance for loan losses on impaired loans includes the allowance for groups of loans which were collectively evaluated for impairment, in addition to the allowance for those loans that were individually evaluated for impairment. The total carrying amount of the groups of loans which were collectively evaluated for impairment at March 31, 2019 and 2020 was ¥257,099 million and ¥260,596 million, respectively.
[4]	Amounts represent the amount of interest income on impaired loans recognized on a cash basis and included in Interest income on loans in the consolidated statements of income.
[5]	The majority of total foreign consist of commercial and industrial loans.

Loans (Impaired Loans Informa_2

Loans (Impaired Loans Information) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	[1]	¥ 716,204	¥ 646,132
Small balance homogeneous loans of which were collectively evaluated for impairment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment		¥ 260,596	¥ 257,099
[1]	These impaired loans do not require an allowance for loan losses because the MHFG Group has sufficient collateral to cover probable loan losses.

Loans (Troubled Debt Restructur

Loans (Troubled Debt Restructurings Entered Modified Periods by Type of Concession Granted) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	¥ 1,155	¥ 984
Loan forgiveness or debt to equity swaps charge-off		8,908	1,964
Interest rate reduction and/or postponement of principal and/or interest		592,989	566,325
Domestic
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	689
Loan forgiveness or debt to equity swaps charge-off		4,002
Interest rate reduction and/or postponement of principal and/or interest		478,830	522,292
Domestic | Manufacturing
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]	689
Loan forgiveness or debt to equity swaps charge-off		3,806
Interest rate reduction and/or postponement of principal and/or interest		148,564	134,544
Domestic | Construction and real estate
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		31,803	39,254
Domestic | Services
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		78,211	87,468
Domestic | Wholesale and retail
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps charge-off		196
Interest rate reduction and/or postponement of principal and/or interest		169,224	167,299
Domestic | Transportation and communications
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		18,700	33,991
Domestic | Banks and other financial institutions
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		16,962	17,286
Domestic | Other industries
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		1,366	120
Domestic | Individuals
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		14,000	42,330
Foreign
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1],[2]	466	984
Loan forgiveness or debt to equity swaps charge-off		4,906	1,964
Interest rate reduction and/or postponement of principal and/or interest		¥ 114,159	¥ 44,033
[1]	Amounts represent the book values of loans immediately after the restructurings.
[2]	The majority of total foreign consist of commercial and industrial loans.

Loans (Payment Defaults Occurre

Loans (Payment Defaults Occurred During Periods with Respect to Loans Modified as Troubled Debt Restructurings within Previous Six Months) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Financing Receivable, Modifications [Line Items]
Recorded investment	¥ 41,814	¥ 27,880
Domestic
Financing Receivable, Modifications [Line Items]
Recorded investment	30,372	22,462
Domestic | Manufacturing
Financing Receivable, Modifications [Line Items]
Recorded investment	3,752	1,173
Domestic | Construction and real estate
Financing Receivable, Modifications [Line Items]
Recorded investment	345	121
Domestic | Services
Financing Receivable, Modifications [Line Items]
Recorded investment	3,822	1,335
Domestic | Wholesale and retail
Financing Receivable, Modifications [Line Items]
Recorded investment	19,018	15,087
Domestic | Transportation and communications
Financing Receivable, Modifications [Line Items]
Recorded investment	824	878
Domestic | Banks and other financial institutions
Financing Receivable, Modifications [Line Items]
Recorded investment	66	66
Domestic | Other industries
Financing Receivable, Modifications [Line Items]
Recorded investment	0	1,650
Domestic | Individuals
Financing Receivable, Modifications [Line Items]
Recorded investment	2,545	2,152
Foreign
Financing Receivable, Modifications [Line Items]
Recorded investment	¥ 11,442	¥ 5,418

Loans (Age Analysis of Past Due

Loans (Age Analysis of Past Due Loans) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020		Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		¥ 160,970		¥ 155,737
Current		87,516,199		82,796,353
Total	[1]	87,677,169		82,952,090
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		130,853		128,542
Current		55,899,658		54,280,602
Total		56,030,511		54,409,144
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		12,492		9,759
Current		9,718,536		9,544,095
Total		9,731,028		9,553,854
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		23,471		33,156
Current		9,579,962		8,917,421
Total		9,603,433		8,950,577
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		8,054		4,323
Current		5,984,457		5,012,648
Total		5,992,511		5,016,971
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		16,166		10,897
Current		5,203,561		5,148,459
Total		5,219,727		5,159,356
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		2,142		2,738
Current		3,830,742		3,690,753
Total		3,832,884		3,693,491
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		109		493
Current		4,634,333		4,345,096
Total		4,634,442		4,345,589
Domestic | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current		2,198,805		2,358,904
Total		2,198,805		2,358,904
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,374		59
Current		5,387,973		5,472,538
Total		5,389,347		5,472,597	[2]
Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		67,045		67,117
Current		9,361,289		9,790,688
Total		9,428,334		9,857,805
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		30,117		27,195
Current		31,616,541		28,515,751
Total		31,646,658	[3]	28,542,946
Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total		10,475,277		9,086,721
Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total		317,284		296,872
30-59 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		27,589		33,642
30-59 Days Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		26,375		32,974
30-59 Days Past Due | Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,109		2,210
30-59 Days Past Due | Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,266		1,010
30-59 Days Past Due | Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		792		633
30-59 Days Past Due | Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,748		1,614
30-59 Days Past Due | Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		56		363
30-59 Days Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due				3
30-59 Days Past Due | Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		28		2
30-59 Days Past Due | Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		21,376		27,139
30-59 Days Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,214		668
60-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		15,179		15,142
60-89 Days Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		14,998		14,931
60-89 Days Past Due | Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		386		513
60-89 Days Past Due | Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		687		1,054
60-89 Days Past Due | Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		548		196
60-89 Days Past Due | Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		2,446		1,415
60-89 Days Past Due | Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		35		256
60-89 Days Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due				484
60-89 Days Past Due | Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		20
60-89 Days Past Due | Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		10,876		11,013
60-89 Days Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		181		211
90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		118,202		106,953
90 Days or More Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		89,480		80,637
90 Days or More Past Due | Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		10,997		7,036
90 Days or More Past Due | Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		21,518		31,092
90 Days or More Past Due | Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		6,714		3,494
90 Days or More Past Due | Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		11,972		7,868
90 Days or More Past Due | Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		2,051		2,119
90 Days or More Past Due | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		109		6
90 Days or More Past Due | Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,326		57
90 Days or More Past Due | Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		34,793		28,965
90 Days or More Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		¥ 28,722		¥ 26,316
[1]	Amounts represent loan balances before deducting unearned income and deferred loan fees.
[2]	Other industries of domestic includes trade receivables and lease receivables of consolidated VIEs.
[3]	Impaired loans to foreign borrowers decreased by ¥15,960 million due mainly to the sale of certain loans, partly offset by deterioration of credit status of certain other borrowers.

Allowance for Loan Losses (Chan

Allowance for Loan Losses (Changes in Allowance for Loan Losses, Allowance for Loan Losses and Loans Outstanding Disaggregated on Basis of Impairment Method, by Portfolio Segment) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		¥ 307,201	¥ 309,902	¥ 479,673
Provision (credit) for loan losses		156,200	32,459	(126,362)
Charge-offs		(44,358)	(47,524)	(55,862)
Recoveries		27,916	14,103	15,220
Net charge-offs		(16,442)	(33,421)	(40,642)
Others	[1]	(6,104)	(1,739)	(2,767)
Balance at end of fiscal year		440,855	307,201	309,902
Allowance for loan losses of which individually evaluated for impairment		239,088	150,527
Allowance for loan losses of which collectively evaluated for impairment		201,767	156,674
Loans	[2]	87,677,169	82,952,090
Loans of which individually evaluated for impairment		1,034,676	615,098
Loans of which collectively evaluated for impairment		86,642,493	82,336,992
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		252,903	249,072	407,327
Provision (credit) for loan losses		155,576	31,693	(123,470)
Charge-offs		(33,971)	(39,728)	(44,621)
Recoveries		26,155	11,019	12,924
Net charge-offs		(7,816)	(28,709)	(31,697)
Others	[1]	(5,454)	847	(3,088)
Balance at end of fiscal year		395,209	252,903	249,072
Allowance for loan losses of which individually evaluated for impairment		231,941	139,472
Allowance for loan losses of which collectively evaluated for impairment		163,268	113,431
Loans	[2]	71,840,922	66,804,088
Loans of which individually evaluated for impairment		971,153	539,893
Loans of which collectively evaluated for impairment		70,869,769	66,264,195
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		23,230	28,192	36,923
Provision (credit) for loan losses		760	(2,658)	(7,427)
Charge-offs		(3,840)	(2,856)	(2,118)
Recoveries		700	552	814
Net charge-offs		(3,140)	(2,304)	(1,304)
Balance at end of fiscal year		20,850	23,230	28,192
Allowance for loan losses of which individually evaluated for impairment		1,704	2,122
Allowance for loan losses of which collectively evaluated for impairment		19,146	21,108
Loans	[2]	10,112,617	10,596,994
Loans of which individually evaluated for impairment		19,279	20,886
Loans of which collectively evaluated for impairment		10,093,338	10,576,108
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		31,068	32,638	35,423
Provision (credit) for loan losses		(136)	3,424	4,535
Charge-offs		(6,547)	(4,940)	(9,123)
Recoveries		1,061	2,532	1,482
Net charge-offs		(5,486)	(2,408)	(7,641)
Others	[1]	(650)	(2,586)	321
Balance at end of fiscal year		24,796	31,068	¥ 32,638
Allowance for loan losses of which individually evaluated for impairment		5,443	8,933
Allowance for loan losses of which collectively evaluated for impairment		19,353	22,135
Loans	[2]	5,723,630	5,551,008
Loans of which individually evaluated for impairment		44,244	54,319
Loans of which collectively evaluated for impairment		¥ 5,679,386	¥ 5,496,689
[1]	Others includes primarily foreign exchange translation.
[2]	Amounts represent loan balances before deducting unearned income and deferred loan fees.

Premises and equipment-Summary

Premises and equipment-Summary of Premises and Equipment (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	¥ 3,318,686	¥ 3,363,162
Less: Accumulated depreciation and amortization	1,462,438	1,462,210
Premises and equipment—net	1,856,248	1,900,952
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	557,943	563,032
Buildings
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	657,774	826,781
Equipment and furniture
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	442,302	472,186
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	228,383	97,508
Construction in Progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	73,164	37,174
Software
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	¥ 1,359,120	¥ 1,366,481

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Impairment losses	¥ 13,490	¥ 27,428
Depreciation and amortization	234,457	345,560	¥ 169,346
General and Administrative expenses
Property, Plant and Equipment [Line Items]
Impairment losses	6,813	8,910
Occupancy expenses
Property, Plant and Equipment [Line Items]
Impairment losses	6,677	18,518
Retail And Business Banking Company
Property, Plant and Equipment [Line Items]
Impairment losses	6,774	¥ 15,761
Impairment losses on real estate	¥ 5,587

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Changes in Goodwill) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Goodwill [Line Items]
Balance at beginning of fiscal year	¥ 95,151	¥ 95,184	¥ 95,176
Impairment losses recognized	(2,155)	0	0
Foreign exchange translation	1	(33)	8
Balance at end of fiscal year	92,997	95,151	95,184
Gross amount of goodwill	169,313	169,489	170,926
Accumulated impairment losses	¥ 76,316	¥ 74,338	¥ 75,742

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets (Gross Carrying Amount, Accumulated Amortization and Net Carrying Amount of Intangible Assets) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Intangible Assets by Major Class [Line Items]
Gross carrying amount		¥ 128,672	¥ 128,580
Gross carrying amount		8,381	8,702
Net carrying amount		8,381	8,702
Gross carrying amount		137,053	137,282
Accumulated amortization		72,364	63,042
Net carrying amount		56,308	65,538
Net carrying amount		64,689	74,240
Customer relationships
Intangible Assets by Major Class [Line Items]
Gross carrying amount	[1]	126,979	126,882
Accumulated amortization	[1]	70,904	61,630
Net carrying amount	[1]	56,075	65,252
Other
Intangible Assets by Major Class [Line Items]
Gross carrying amount		1,693	1,698
Accumulated amortization		1,460	1,412
Net carrying amount		¥ 233	¥ 286
[1]	Customer relationships were acquired in connection with the merger of MHSC and Shinko on May 7, 2009 and the integration among asset management companies on October 1, 2016. See Note 1 “Basis of presentation and summary of significant accounting policies” for further information.

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets amortization expense recognized	¥ 9,267	¥ 9,604	¥ 9,812

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets (Estimated Aggregate Amortization Expense in Respect of Intangible Assets) (Detail) ¥ in Millions	Mar. 31, 2020JPY (¥)
Finite-Lived Intangible Assets [Line Items]
2021	¥ 8,237
2022	7,702
2023	7,184
2024	6,666
2025	¥ 6,154

Pledged Assets and Collateral_2

Pledged Assets and Collateral (Amounts Pledged as Collateral for Borrowings and for Other Purposes) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Financial Instruments Owned and Pledged as Collateral [Line Items]
Interest-bearing deposits in other banks	¥ 69	¥ 68
Trading account assets	5,705	4,137
Investments	4,155	6,076
Loans	3,887	4,055
Other assets	2,786	1,886
Total	¥ 16,602	¥ 16,222

Pledged Assets and Collateral_3

Pledged Assets and Collateral (Associated Liabilities Collateralized by Pledged Assets) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Deposits	¥ 1,057	¥ 386
Payables under repurchase agreements	5,480	3,435
Payables under securities lending transactions	1,094	1,675
Other short-term borrowings	4,014	519
Long-term debt	213	1,431
Total	¥ 11,858	¥ 7,446

Pledged Assets and Collateral -

Pledged Assets and Collateral - Additional Information (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Assets that Continue to be Recognized, Securitized or Asset-backed Financing Arrangement Assets and any Other Financial Assets Managed Together [Line Items]
Reserve funds maintained with the BOJ	¥ 38,808	¥ 43,552
Reserve funds requires to be maintained by MHFG Group	1,507	1,583
Fair value collateral received that can be sold or repledged	20,663	16,114
Fair value collateral received that can be sold or repledged, value of collateral sold or repledged	¥ 18,824	¥ 12,264

Deposits (Balances of Time Depo

Deposits (Balances of Time Deposits and Certificates of Deposit Issued by Domestic Offices in Amounts of JPY10 Million or More and by Foreign Offices in Amounts of USD100,000 or More) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	¥ 22,243,389	¥ 22,221,945
Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	23,732,543	25,301,760
Time deposits | Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	14,684,619	16,578,642
Time deposits | Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	18,008,751	17,606,520
Certificates of deposit | Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	7,558,770	5,643,303
Certificates of deposit | Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	¥ 5,723,792	¥ 7,695,240

Deposits - Additional Informati

Deposits - Additional Information (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Deposits From Banking Clients [Line Items]
Aggregate amount of demand deposits in overdraft status that have been reclassified as loan balances	¥ 696	¥ 810

Deposits (Balance and Remaining

Deposits (Balance and Remaining Maturities of Time Deposits and Certificates of Deposit Issued by Domestic and Foreign Offices) (Detail) ¥ in Millions	Mar. 31, 2020JPY (¥)
Deposits From Banking Clients [Line Items]
Total	¥ 54,741,586
Bank Time Deposits Liabilities Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	19,660,222
Due after one year through two years	1,676,056
Due after two years through three years	1,159,144
Due after three years through four years	335,659
Due after four years through five years	397,591
Due after five years	212,416
Total	23,441,088
Certificates Of Deposit Liabilities Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	7,418,470
Due after one year through two years	140,300
Total	7,558,770
Bank Time Deposits Liabilities Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	17,936,190
Due after one year through two years	59,530
Due after two years through three years	9,536
Due after three years through four years	6,624
Due after four years through five years	2,788
Due after five years	3,268
Total	18,017,936
Certificates Of Deposit Liabilities Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	5,565,541
Due after one year through two years	80,747
Due after two years through three years	11,224
Due after four years through five years	66,280
Total	5,723,792
Time deposits
Deposits From Banking Clients [Line Items]
Total	41,459,024
Certificates of deposit
Deposits From Banking Clients [Line Items]
Total	13,282,562
Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	27,078,692
Due after one year through two years	1,816,356
Due after two years through three years	1,159,144
Due after three years through four years	335,659
Due after four years through five years	397,591
Due after five years	212,416
Total	30,999,858
Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	23,501,731
Due after one year through two years	140,277
Due after two years through three years	20,760
Due after three years through four years	6,624
Due after four years through five years	69,068
Due after five years	3,268
Total	¥ 23,741,728

Short-Term Borrowings and Lon_3

Short-Term Borrowings and Long-Term Debt (Details of Other Short-Term Borrowings) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Short-term Debt [Line Items]
Borrowings from the Bank of Japan		¥ 4,002,781	¥ 508,627
Other		126,957	189,478
Total		4,914,485	1,994,826
Mizuho Financial Group Inc
Short-term Debt [Line Items]
Commercial paper and short-term notes issued	[1],[2]	730,089	1,274,382
Consolidated VIEs
Short-term Debt [Line Items]
Commercial paper and short-term notes issued	[1]	54,658	22,339
Total		¥ 60,086	¥ 23,495
[1]	Short-term notes are issued under the laws of Japan in the form of commercial paper.
[2]	The amounts of commercial paper and short-term notes issued by MHFG’s subsidiaries were ¥941,182 million and ¥333,200 million, respectively, at March 31, 2019, and ¥411,089 million and ¥319,000 million, respectively, at March 31, 2020.

Short-Term Borrowings and Lon_4

Short-Term Borrowings and Long-Term Debt (Details of Other Short-Term Borrowings) (Parenthetical) (Detail) - Mizuho Financial Group Inc - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Short-term Debt [Line Items]
Commercial paper	¥ 411,089	¥ 941,182
Short-term notes	¥ 319,000	¥ 333,200

Short-Term Borrowings and Lon_5

Short-Term Borrowings and Long-Term Debt (Long-Term Debt with Original Maturities of More than One Year) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Debt Instrument [Line Items]
Obligations under finance leases	¥ 16,250	¥ 25,020
Loan participation borrowings	149,398	142,838
Senior borrowings and bonds	6,402,157	7,503,032
Subordinated borrowings and bonds	3,778,347	3,858,510
Total	¥ 10,346,152	¥ 11,529,400

Short-Term Borrowings and Lon_6

Short-Term Borrowings and Long-Term Debt (Interest Rates and Maturities of Senior Borrowings and Bonds, and Subordinated Borrowings and Bonds) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Debt Instrument [Line Items]
Borrowings and bonds		¥ 10,180,504	¥ 11,361,542
Senior borrowings and bonds
Debt Instrument [Line Items]
Borrowings and bonds		6,402,157	7,503,032
Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		549,647	2,057,156
Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		2,744,713	2,765,247
Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Borrowings and bonds		609,346	324,162
Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		606,095	656,029
Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		1,682,540	1,493,617
Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Borrowings and bonds		209,816	206,821
Subordinated borrowings and bonds
Debt Instrument [Line Items]
Borrowings and bonds		3,778,347	3,858,510
Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		3,370,234	3,442,438
Subordinated borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		¥ 408,113	¥ 416,072
Maximum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	8.10%
Maturities, End	[2]	2050-01
Maximum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	8.25%
Maturities, End	[2]	2048-03
Maximum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	12.40%
Maturities, End	[2]	2039-09
Maximum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	51.60%
Maturities, End	[2]	2050-03
Maximum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	37.20%
Maturities, End	[2]	2059-12
Maximum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	25.00%
Maturities, End	[2]	2030-10
Maximum [Member] | Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	4.26%
Maximum [Member] | Subordinated borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	4.70%
Maturities, End	[2]	2025-10
Minimum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2020-04
Minimum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2020-04
Minimum [Member] | Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	0.02%
Maturities, Start	[2]	2020-04
Minimum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2020-04
Minimum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2020-04
Minimum [Member] | Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2020-06
Minimum [Member] | Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0.39%
Maturities, Start	[2]	2020-08
Minimum [Member] | Subordinated borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	4.30%
Maturities, Start	[2]	2022-07
[1]	The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2020.
[2]	Maturity information disclosed is the range of maturities at March 31, 2020.

Short-Term Borrowings and Lon_7

Short-Term Borrowings and Long-Term Debt (Contractual Maturities of Long-Term Debt) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Debt Instrument [Line Items]
2021	¥ 559,447
2022	1,430,157
2023	1,234,962
2024	697,214
2025	1,023,243
2026 and thereafter	5,401,129
Total	¥ 10,346,152	¥ 11,529,400

Other Assets and Liabilities (D

Other Assets and Liabilities (Details of Other Assets and Liabilities) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Other assets:
Receivables from brokers, dealers and customers for securities transactions	[1]	¥ 783,439	¥ 1,517,235
Other		358,702	400,676
Collateral pledged for derivative transactions		1,246,026	856,439
Margins provided for futures contracts		602,039	159,747
Other		941,167	857,814
Prepaid pension cost		711,981	850,472
ROU assets	[2],[3]	613,068
Security deposits		107,294	123,317
Loans held for sale		60,084	24,921
Other		542,079	485,383
Total		5,965,879	5,276,004
Other liabilities:
Payables to brokers, dealers and customers for securities transactions	[1]	2,161,075	2,572,315
Other		375,127	442,776
Guaranteed trust principal	[4]	824,431	809,450
Lease liabilities	[2],[3]	¥ 627,250
Operating Lease, Liability, Statement of Financial Position [Extensible List]		us-gaap:OperatingLeaseLiability
Collateral accepted for derivative transactions		¥ 846,426	589,411
Margins accepted for futures contracts		797,317	339,863
Unearned income	[5]	122,072	126,594
Other		1,244,697	1,052,297
Total		¥ 6,998,395	¥ 5,932,706
[1]	Receivables from brokers, dealers and customers for securities transactions included ¥555,938 million and ¥3,136 million of such receivables of consolidated VIEs at March 31, 2019 and 2020, respectively. Payables to brokers, dealers and customers for securities transactions included ¥620,766 million and ¥3,225 million of such payables of consolidated VIEs at March 31, 2019 and 2020, respectively.
[2]	ROU assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets.
[3]	ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 on April 1, 2019. See Note 1 “Basis of presentation and summary of significant accounting policies” and Note 2 “Issued accounting pronouncements” for further information.
[4]	Guaranteed trust principal, included in All other liabilities in the disclosure about consolidated VIEs in the accompanying balance sheets, is a liability of certain consolidated trust arrangements that meet the definition of a VIE for which the MHFG Group provides guarantees for the repayment of principal. See Note 24 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts.
[5]	Unearned income is primarily comprised of loan fees received from consumer loan customers when loans are made. This income is deferred and recognized in earnings over the life of the loan.

Other Assets and Liabilities _2

Other Assets and Liabilities (Details of Other Assets and Liabilities) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Other Assets and Other Liabilities [Line Items]
Accounts receivable from brokers, dealers and customers for securities transactions	[1]	¥ 783,439	¥ 1,517,235
Accounts payable to brokers, dealers and customers for securities transactions	[1]	2,161,075	2,572,315
Consolidated VIEs
Other Assets and Other Liabilities [Line Items]
Accounts receivable from brokers, dealers and customers for securities transactions		3,136	555,938
Accounts payable to brokers, dealers and customers for securities transactions		¥ 3,225	¥ 620,766
[1]	Receivables from brokers, dealers and customers for securities transactions included ¥555,938 million and ¥3,136 million of such receivables of consolidated VIEs at March 31, 2019 and 2020, respectively. Payables to brokers, dealers and customers for securities transactions included ¥620,766 million and ¥3,225 million of such payables of consolidated VIEs at March 31, 2019 and 2020, respectively.

Preferred Stock (Composition of

Preferred Stock (Composition of Preferred Stock) (Detail) - shares	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Class Fourteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	900,000,000	900,000,000	900,000,000
Number of shares Issued	0	0	0
Class Fifteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	900,000,000	900,000,000	900,000,000
Number of shares Issued	0	0	0
Class Sixteen Preferred Stock
Class of Stock [Line Items]
Number of shares Authorized	1,500,000,000	1,500,000,000	1,500,000,000
Number of shares Issued	0	0	0

Common Stock - Summary of Chang

Common Stock - Summary of Changes in Number of Issued Shares of Common Stock (Detail) - shares	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Class of Stock [Line Items]
Balance at beginning of fiscal year	25,392,498,945	25,389,644,945	25,386,307,945
Issuance of new shares of common stock due to exercise of stock acquisition rights		2,854,000	3,337,000
Balance at end of fiscal year	25,392,498,945	25,392,498,945	25,389,644,945

Dividends - Additional Informat

Dividends - Additional Information (Detail) ¥ in Millions	12 Months Ended
	Mar. 31, 2020JPY (¥)
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital stock	¥ 2,256,768
Capital surplus	1,196,660
Retained earnings	¥ 1,913,788
Description of dividend payment restrictions	Pursuant to the Companies Act, in making a distribution of retained earnings, an entity must set aside in its legal reserve an amount equal to one-tenth of the amount of retained earnings so distributed, until its legal reserve reaches one-quarter of its capital stock.
Percentage of retained earnings set aside for legal reserve	0.10
Legal reserve	¥ 1,201,010
Maximum amount available for dividends under Company Law and the Banking Law	¥ 1,904,452
Minimum Common Equity Tier 1 ratio required for capital adequacy purposes	4.50%
Japan Gaap Additional PaidIn Capital [Member]
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Legal reserve	¥ 1,196,660
Japan Gaap Retained Earnings [Member]
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Legal reserve	¥ 4,350

Accumulated other comprehensi_3

Accumulated other comprehensive income (loss), net of tax Changes in Each Component of AOCI) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		¥ 9,501,493	¥ 9,503,700
Less: reclassification adjustments for losses (gains) included in net income		(23,388)
Change during year		(172,055)	(42,945)	¥ 222,538
Balance at end of fiscal year		9,175,624	9,501,493	9,503,700
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		164,021	1,741,894	1,521,163
Cumulative effect of change in accounting principles	[1]	(1,052)	(1,535,142)
Balance at beginning of fiscal year, adjusted		162,969	206,752	1,521,163
Change during year		(172,463)	(42,731)	220,731
Balance at end of fiscal year		(9,494)	164,021	1,741,894
Net unrealized gains (losses) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		22,019	1,556,585	1,461,302
Cumulative effect of change in accounting principles	[1]		(1,525,064)
Balance at beginning of fiscal year, adjusted		22,019	31,521	1,461,302
Unrealized gains (losses) during year		(22,566)	(11,358)	282,141
Less: reclassification adjustments for losses (gains) included in net income		(19,045)	1,856	(186,858)
Change during year		(41,611)	(9,502)	95,283
Balance at end of fiscal year		(19,592)	22,019	1,556,585
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		(58,558)	(35,076)	(5,535)
Cumulative effect of change in accounting principles	[1]	(1,052)
Balance at beginning of fiscal year, adjusted		(59,610)	(35,076)	(5,535)
Foreign currency translation adjustments during year		(49,888)	(22,737)	(26,936)
Less: reclassification adjustments for losses (gains) included in net income		(374)	(745)	(2,605)
Change during year		(50,262)	(23,482)	(29,541)
Balance at end of fiscal year		(109,872)	(58,558)	(35,076)
Pension liability adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year		196,446	220,385	65,396
Unrealized gains (losses) during year		(122,219)	(17,243)	157,737
Less: reclassification adjustments for losses (gains) included in net income		(4,772)	(6,696)	(2,748)
Change during year		(126,991)	(23,939)	154,989
Balance at end of fiscal year		69,455	196,446	¥ 220,385
Accumulated Own Credit Risk Adjustment Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	[2]	4,114
Cumulative effect of change in accounting principles	[1],[2]		(10,078)
Balance at beginning of fiscal year, adjusted	[2]	4,114	(10,078)
Unrealized gains (losses) during year	[2]	45,560	14,293
Less: reclassification adjustments for losses (gains) included in net income	[2]	841	(101)
Change during year	[2]	46,401	14,192
Balance at end of fiscal year	[2]	¥ 50,515	¥ 4,114
[1]	See Note 2 “Issued accounting pronouncements” for further details of the cumulative-effect adjustment for AOCI.
[2]	The MHFG Group adopted ASU No.2016-01 on April 1, 2018. The ASU requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. See Note 2 “Issued accounting pronouncements” for further details.

Accumulated other comprehensi_4

Accumulated other comprehensive income (loss), net of tax (Amounts Reclassified Out of Accumulated Other Comprehensive Income into Net Income) (Detail) ¥ in Millions	12 Months Ended
	Mar. 31, 2020JPY (¥)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	¥ 33,176	[1]
Tax effect	(9,788)	[2]
Net of tax before allocation to noncontrolling interests	23,388
Net of tax attributable to noncontrolling interests	(38)	[2]
Net of tax attributable to MHFG shareholders	23,350
Accumulated Net Unrealized Investment Gain (Loss) | Gain (Loss) on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	27,449	[1]
Tax effect	(8,410)	[2]
Net of tax before allocation to noncontrolling interests	19,039
Net of tax attributable to noncontrolling interests	6	[2]
Net of tax attributable to MHFG shareholders	19,045
Accumulated Net Unrealized Investment Gain (Loss) | Foreign exchange adjustments gains (losses)-net
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	374	[1]
Net of tax before allocation to noncontrolling interests	374
Net of tax attributable to MHFG shareholders	374
Accumulated Defined Benefit Plans Adjustment | Salaries and employee benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	6,618	[1]
Tax effect	(1,765)	[2]
Net of tax before allocation to noncontrolling interests	4,853
Net of tax attributable to noncontrolling interests	(81)	[2]
Net of tax attributable to MHFG shareholders	4,772
Accumulated Own Credit Risk Adjustment | Other Noninterest Income (Expenses)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	(1,265)	[1]
Tax effect	387	[2]
Net of tax before allocation to noncontrolling interests	(878)
Net of tax attributable to noncontrolling interests	37	[2]
Net of tax attributable to MHFG shareholders	¥ (841)
[1]	The financial statement line item in which the amounts in the Before tax column are reported in the Consolidated statements of income is listed to the right of the table.
[2]	The financial statement line items in which the amounts in the Tax effect and the Net of tax attributable to noncontrolling interest columns are reported in the consolidated statements of income are Income tax expense and Net income, respectively.

Regulatory Matters (Capital Req

Regulatory Matters (Capital Requirements and Regulatory Adjustments Over Transitional Period) (Detail)	12 Months Ended
	Mar. 31, 2020
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%
March 2019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Phase out of recognition of capital instruments that no longer qualify as capital	30.00%
Capital conservation buffer	2.50%
Countercyclical capital buffer	0.05%	[1]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[2]
Minimum Leverage Ratio	3.00%
March 2019 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	4.50%
March 2019 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	6.00%
March 2020
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Phase out of recognition of capital instruments that no longer qualify as capital	20.00%
Capital conservation buffer	2.50%
Countercyclical capital buffer	0.01%	[1]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[2]
Minimum Leverage Ratio	3.00%
March 2020 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	4.50%
March 2020 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	6.00%
March 2021
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Phase out of recognition of capital instruments that no longer qualify as capital	10.00%
Capital conservation buffer	2.50%
Countercyclical capital buffer	0.01%	[1]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[2]
Minimum Leverage Ratio	3.00%
March 2021 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	4.50%
March 2021 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	6.00%
March 2022
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Phase out of recognition of capital instruments that no longer qualify as capital	0.00%
Capital conservation buffer	2.50%
Countercyclical capital buffer	0.01%	[1]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[2]
Minimum Leverage Ratio	3.00%
March 2022 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	4.50%
March 2022 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	6.00%
March 2023
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Phase out of recognition of capital instruments that no longer qualify as capital	0.00%
Capital conservation buffer	2.50%
Countercyclical capital buffer	0.01%	[1]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[2]
Minimum Leverage Ratio	3.50%	[3]
March 2023 | Common Equity Tier 1 Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	4.50%
March 2023 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	6.00%
[1]	Figures assume that the countercyclical capital buffer will continue to be 0.01% after March 2020.
[2]	Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB and D-SIB continue to be 1.0% on a fully effective basis in future years.
[3]	This figure includes a leverage ratio buffer required to be met at 50% of the additional loss absorbency requirements applied to the Group as a G-SIB under the finalized Basel III reforms.

Regulatory Matters (Capital R_2

Regulatory Matters (Capital Requirements and Regulatory Adjustments Over Transitional Period) (Parenthetical) (Detail)	12 Months Ended
	Mar. 31, 2020
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%
March 2023
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Countercyclical capital buffer	0.01%	[1]
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[2]
March 2023 | Basel III
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Leverage ratio buffer	50.00%
[1]	Figures assume that the countercyclical capital buffer will continue to be 0.01% after March 2020.
[2]	Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB and D-SIB continue to be 1.0% on a fully effective basis in future years.

Regulatory Matters (Capital Ade

Regulatory Matters (Capital Adequacy Ratios of MHFG, MHBK, and MHTB Calculated in Accordance with Japanese GAAP and Guidelines Established by Financial Services Agency) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Common Equity Tier 1 capital:
Actual	¥ 2,256,768
Required	120.00%
Common Equity Tier 1 capital:
Required	4.50%
Leverage Ratio:
Required	3.00%
Mizuho Financial Group Inc | Consolidated
Common Equity Tier 1 capital:
Required	¥ 4,978,000	¥ 4,661,000
Actual	7,245,000	7,390,000
Required	5,910,000	5,529,000
Actual	¥ 9,024,000	¥ 9,232,000
Required	9.51%	9.55%
Actual	14.52%	15.94%
Required	¥ 7,152,000	¥ 6,687,000
Actual	¥ 10,722,000	¥ 10,918,000
Required	11.51%	11.55%
Actual	17.25%	18.85%
Required	¥ 6,629,000	¥ 6,257,000
Actual	¥ 9,024,000	¥ 9,232,000
Common Equity Tier 1 capital:
Required	8.01%	8.05%
Actual	11.65%	12.76%
Leverage Ratio:
Required	3.00%	3.00%
Actual	4.08%	4.42%
Mizuho Bank Limited | Consolidated
Common Equity Tier 1 capital:
Required	¥ 2,567,000	¥ 2,388,000
Actual	6,501,000	6,690,000
Required	3,422,000	3,184,000
Actual	¥ 8,275,000	¥ 8,527,000
Required	6.00%	6.00%
Actual	14.50%	16.06%
Required	¥ 4,563,000	¥ 4,246,000
Actual	¥ 9,865,000	¥ 10,098,000
Required	8.00%	8.00%
Actual	17.29%	19.02%
Required	¥ 6,160,000	¥ 5,758,000
Actual	¥ 8,275,000	¥ 8,527,000
Common Equity Tier 1 capital:
Required	4.50%	4.50%
Actual	11.39%	12.60%
Leverage Ratio:
Required	3.00%	3.00%
Actual	4.02%	4.44%
Mizuho Bank Limited | Non-consolidated
Common Equity Tier 1 capital:
Required	¥ 2,403,000	¥ 2,272,000
Actual	6,130,000	6,363,000
Required	3,204,000	3,029,000
Actual	¥ 7,905,000	¥ 8,199,000
Required	6.00%	6.00%
Actual	14.80%	16.23%
Required	¥ 4,272,000	¥ 4,039,000
Actual	¥ 9,482,000	¥ 9,757,000
Required	8.00%	8.00%
Actual	17.75%	19.32%
Required	¥ 5,884,000	¥ 5,517,000
Actual	¥ 7,905,000	¥ 8,199,000
Common Equity Tier 1 capital:
Required	4.50%	4.50%
Actual	11.47%	12.60%
Leverage Ratio:
Required	3.00%	3.00%
Actual	4.03%	4.45%
Mizuho Trust & Banking Company Limited | Consolidated
Common Equity Tier 1 capital:
Required	¥ 93,000	¥ 95,000
Actual	489,000	500,000
Required	124,000	127,000
Actual	¥ 489,000	¥ 501,000
Required	6.00%	6.00%
Actual	23.66%	23.70%
Required	¥ 165,000	¥ 169,000
Actual	¥ 491,000	¥ 505,000
Required	8.00%	8.00%
Actual	23.74%	23.87%
Required	¥ 216,000	¥ 229,000
Actual	¥ 489,000	¥ 501,000
Common Equity Tier 1 capital:
Required	4.50%	4.50%
Actual	23.64%	23.67%
Leverage Ratio:
Required	3.00%	3.00%
Actual	6.79%	6.55%
Mizuho Trust & Banking Company Limited | Non-consolidated
Common Equity Tier 1 capital:
Required	¥ 93,000	¥ 94,000
Actual	475,000	494,000
Required	123,000	126,000
Actual	¥ 475,000	¥ 494,000
Required	6.00%	6.00%
Actual	23.10%	23.58%
Required	¥ 165,000	¥ 168,000
Actual	¥ 477,000	¥ 498,000
Required	8.00%	8.00%
Actual	23.18%	23.75%
Required	¥ 214,000	¥ 227,000
Actual	¥ 475,000	¥ 494,000
Common Equity Tier 1 capital:
Required	4.50%	4.50%
Actual	23.10%	23.58%
Leverage Ratio:
Required	3.00%	3.00%
Actual	6.66%	6.53%

Regulatory Matters (Capital A_2

Regulatory Matters (Capital Adequacy Ratios of MHFG, MHBK, and MHTB Calculated in Accordance with Japanese GAAP and Guidelines Established by Financial Services Agency) (Parenthetical) (Detail)		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer		2.50%	2.50%
Additional loss absorbency requirements for G-SIBs and D-SIBs		1.00%
March 2019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Additional loss absorbency requirements for G-SIBs and D-SIBs	[1]	1.00%
Countercyclical capital buffer	[2]	0.05%
March 2020
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Additional loss absorbency requirements for G-SIBs and D-SIBs	[1]	1.00%
Countercyclical capital buffer	[2]	0.01%
[1]	Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB and D-SIB continue to be 1.0% on a fully effective basis in future years.
[2]	Figures assume that the countercyclical capital buffer will continue to be 0.01% after March 2020.

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail) ¥ in Billions	12 Months Ended
	Mar. 31, 2020JPY (¥)
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	120.00%
Increments of capital investment	10.00%
Tier 2 capital	¥ 337.4
Leverage ratio	3.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%
Description of regulatory actions for not maintaining the minimum capital ratio concerning securities subsidiaries	A capital ratio of less than 140% will call for regulatory reporting and a capital ratio of less than 100% may lead to a temporary suspension of all or part of the business operations and further, to the cancellation of the license to act as a securities broker and dealer.
Maximum
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Buffer ranging percentage	2.50%
Minimum
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Buffer ranging percentage	0.00%
Minimum | Regulatory reporting
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	140.00%
Minimum | Temporary suspension
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	100.00%
Basel III
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Tier 1 capital ratio	6.00%
Common Equity Tier 1	4.50%
Basel III | Minimum
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	8.00%
March 2016
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Additional loss absorbency requirements for G-SIBs and D-SIBs	0.25%

Earnings Per Common Share (Comp

Earnings Per Common Share (Computation of Basic and Diluted Earnings Per Common Share) (Detail) - JPY (¥) ¥ / shares in Units, shares in Thousands, ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Net income:
Net income attributable to MHFG common shareholders		¥ 150,195	¥ 84,471	¥ 577,608
Effect of dilutive securities
Net income attributable to common shareholders after assumed conversions		¥ 150,195	¥ 84,471	¥ 577,608
Shares:
Weighted average common shares outstanding		25,373,681	25,362,376	25,366,345
Effect of dilutive securities:
Stock options and the common shares of MHFG under the stock compensation programs	[1]	1,583	4,522	7,586
Weighted average common shares after assumed conversions		25,375,264	25,366,898	25,373,931
Earnings per common share:
Basic net income per common share		¥ 5.92	¥ 3.33	¥ 22.77
Diluted net income per common share	[1]	¥ 5.92	¥ 3.33	¥ 22.76
[1]	For the fiscal year ended March 31, 2020, the performance-based plan under the stock compensation programs could potentially dilute earnings per common share but were not included in the computation of diluted earnings per common share due to their antidilutive effects.

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Current:
Domestic	¥ 96,231	¥ 116,695	¥ 130,573
Foreign	52,885	49,871	47,020
Total current tax expense	149,116	166,566	177,593
Deferred:
Domestic	(111,341)	(162,475)	58,078
Foreign	9,400	5,244	1,933
Total deferred tax expense (benefit)	(101,941)	(157,231)	60,011
Income tax expense	¥ 47,175	¥ 9,335	¥ 237,604

Income Taxes (Detailed Amounts

Income Taxes (Detailed Amounts of Tax Effects of Items Recorded Directly in Equity) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Net unrealized gains (losses) on available-for-sale securities:
Unrealized gains (losses)	¥ (10,012)	¥ (3,940)	¥ 123,186
Less: reclassification adjustments	(8,410)	889	(82,828)
Total	(18,422)	(3,051)	40,358
Pension liability adjustments:
Unrealized gains (losses)	(52,888)	(6,558)	66,331
Less: reclassification adjustments	(1,765)	(2,370)	190
Total	(54,653)	(8,928)	66,521
Own credit risk adjustments:
Unrealized gains (losses)	5,052	3,033	0
Less: reclassification adjustments	387	(47)	0
Total	5,439	2,986	0
Total tax effect before allocation to noncontrolling interests	¥ (67,636)	¥ (8,993)	¥ 106,879

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Income Taxes [Line Items]
Net operating loss carryforwards	¥ 637,000
Deferred tax liabilities	(110,839)	¥ 58,345
Changes that directly affected Income tax expense	5,984	(2,444)	¥ (9,102)
Unrecognized tax benefits, that would affect effective tax rate	3,374	12,323	2,345
Unrecognized tax benefits, interest and penalties	1,477	¥ 2,164	¥ 888
Mizuho Securities Company Limited | Japan
Income Taxes [Line Items]
Net operating loss carryforwards	333,000
Mizuho Financial Group Inc
Income Taxes [Line Items]
Undistributed earnings	220,000
Deferred tax liabilities	¥ 21,000

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Income Tax Expense at Effective Statutory Tax Rate to Actual Income Tax Expense) (Detail) - JPY (¥) ¥ in Millions		Dec. 22, 2017	Mar. 31, 2018	Mar. 31, 2020	Mar. 31, 2019		Mar. 31, 2018
Reconciliation Of Income Tax Expense Benefit And Statutory Federal Tax Rate [Line Items]
Income before income tax expense				¥ 153,490	¥ 85,060		¥ 839,298
Effective statutory tax rate		35.00%	21.00%	30.62%	30.62%		30.86%
Income tax calculated at the statutory tax rate				¥ 46,999	¥ 26,045		¥ 259,007
Income not subject to tax				(7,758)	(8,861)		(9,312)
Expenses not deductible for tax purposes				1,290	1,389		1,421
Tax rate differentials of subsidiaries				(5,756)	(3,522)		(2,696)
Change in valuation allowance				5,984	(2,444)		(9,102)
Noncontrolling interest income (loss) of consolidated VIEs				14,796	3,475		(5,928)
Effect of enacted change in tax rates				(210)	(11)		6,863	[1]
Change in unrecognized tax benefits					9,420
Other	[2]			(8,170)	(16,156)	[3]	(2,649)
Income tax expense				¥ 47,175	¥ 9,335		¥ 237,604
[1]	On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act, which includes a reduction in the U.S. federal corporate income tax rate from 35% to 21%. The decrease in the Group’s balance of net deferred tax assets, reflecting such tax rate reductions, was recognized as an increase to Income tax expense in the fiscal year ended March 31, 2018. The MHFG Group has completed its analysis and accounting under Staff Accounting Bulletin No. 118 for the effects of the Act.
[2]	Change in undistributed earnings of subsidiaries of ¥(1,972) million and ¥(21,347) million have been reclassified to Other for the fiscal years ended March 31, 2018 and 2019, respectively, in order to conform to the current period’s presentation.
[3]	In the fiscal year ended March 31, 2019, the MHFG Group derecognized the majority of deferred tax liabilities for undistributed earnings of foreign subsidiaries because the Group has intent and ability to reinvest those earnings indefinitely in certain foreign subsidiaries.

Income Taxes (Reconciliation _2

Income Taxes (Reconciliation of Income Tax Expense at Effective Statutory Tax Rate to Actual Income Tax Expense) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	Dec. 22, 2017	Mar. 31, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Reconciliation Of Income Tax Expense Benefit And Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate	35.00%	21.00%	30.62%	30.62%	30.86%
Reclassification Of Undistributed Earnings In Subsidiaries To Others [Member]
Reconciliation Of Income Tax Expense Benefit And Statutory Federal Tax Rate [Line Items]
Change in undistributed earnings of subsidaries reclassified to others				¥ (21,347)	¥ (1,972)

Income Taxes (Components of Net

Income Taxes (Components of Net Deferred Tax Assets (Liabilities)) (Detail) - JPY (¥)		Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2018	Mar. 31, 2017
Deferred tax assets:
Lease liabilities	[1]	¥ 191,873,000,000
Allowance for loan losses		165,665,000,000		¥ 122,585,000,000
Premises and equipment		77,513,000,000		73,944,000,000
Available-for-sale securities		5,532,000,000
Derivative financial instruments		4,647,000,000		48,487,000,000
Investments		3,563,000,000
Net operating loss carryforwards	[2]	163,264,000,000		167,755,000,000
Other		203,004,000,000		216,568,000,000
Deferred Tax Assets, Gross, Total		815,061,000,000		629,339,000,000
Valuation allowance		(165,278,000,000)	[2]	(158,581,000,000)	[2]	¥ (163,358,000,000)	¥ (438,344,000,000)
Deferred tax assets, net of valuation allowance		649,783,000,000		470,758,000,000
Deferred tax liabilities:
Prepaid pension cost and accrued pension liabilities		202,930,000,000		247,694,000,000
ROU assets	[1]	188,591,000,000
Investments				198,495,000,000
Available-for-salesecurities				12,426,000,000
Trading securities		58,266,000,000		9,158,000,000
Other		89,157,000,000		61,330,000,000
Deferred tax liabilities		538,944,000,000		529,103,000,000
Net deferred tax assets (liabilities)		¥ 110,839,000,000		¥ (58,345,000,000)
[1]	ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 on April 1, 2019. See Note 1 “Basis of presentation and summary of significant accounting policies” and Note 2 “Issued accounting pronouncements” for further information.
[2]	The amount includes ¥107,246 million and ¥101,498 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2019 and 2020, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥88,294 million and ¥86,591 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.

Income Taxes (Components of N_2

Income Taxes (Components of Net Deferred Tax Assets (Liabilities)) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2018	Mar. 31, 2017
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Net operating loss carryforwards	[1]	¥ 163,264		¥ 167,755
Valuation allowance		165,278	[1]	158,581	[1]	¥ 163,358	¥ 438,344
Mizuho Securities Company Limited
Schedule Of Deferred Income Tax Assets And Liabilities [Line Items]
Net operating loss carryforwards		101,498		107,246
Valuation allowance		¥ 86,591		¥ 88,294
[1]	The amount includes ¥107,246 million and ¥101,498 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2019 and 2020, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥88,294 million and ¥86,591 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.

Income Taxes (Breakdown of Net

Income Taxes (Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020		Mar. 31, 2019
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[1]	¥ 163,264		¥ 167,755
Operating loss, Valuation allowance		(141,000)		(140,000)
Deferred tax assets,Operating loss carryforward net of valuation allowance		22,000		28,000
Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		110,000	[2]	111,000	[3]
Operating loss, Valuation allowance		(92,000)	[2]	(92,000)	[3]
Deferred tax assets,Operating loss carryforward net of valuation allowance		18,000	[2]	19,000	[3]
United States of America
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		3,000		8,000
Deferred tax assets,Operating loss carryforward net of valuation allowance		3,000		8,000
United Kingdom
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[4]	47,000		46,000
Operating loss, Valuation allowance	[4]	(47,000)		(46,000)
Others
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		3,000		3,000
Operating loss, Valuation allowance		(2,000)		(2,000)
Deferred tax assets,Operating loss carryforward net of valuation allowance		¥ 1,000		¥ 1,000
[1]	The amount includes ¥107,246 million and ¥101,498 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2019 and 2020, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥88,294 million and ¥86,591 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.
[2]	¥101 billion of the Japan deferred tax assets of ¥110 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026.
[3]	¥107 billion of the Japan deferred tax assets of ¥111 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026
[4]	The United Kingdom net operating loss carryforwards may be carried forward indefinitely for tax purposes.

Income Taxes (Breakdown of Ne_2

Income Taxes (Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[1]	¥ 163,264		¥ 167,755
Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		110,000	[2]	111,000	[3]
Mizuho Securities Company Limited
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		¥ 101,498		¥ 107,246
Operating loss carryforwards, expiration date		Mar. 31, 2026		Mar. 31, 2026
Mizuho Securities Company Limited | Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		¥ 101,000		¥ 107,000
[1]	The amount includes ¥107,246 million and ¥101,498 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2019 and 2020, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥88,294 million and ¥86,591 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.
[2]	¥101 billion of the Japan deferred tax assets of ¥110 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026.
[3]	¥107 billion of the Japan deferred tax assets of ¥111 billion is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026

Income Taxes (Roll-forward of V

Income Taxes (Roll-forward of Valuation Allowance) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2018
Valuation Allowance [Line Items]
Balance at beginning of fiscal year	¥ 158,581	[1]	¥ 163,358		¥ 438,344
Changes that directly affected Income tax expense	5,984		(2,444)		(9,102)
Expiration of net operating loss carryforwards					(264,234)
Others	713		(2,333)		(1,650)
Total	713		(2,333)		(265,884)
Balance at end of fiscal year	¥ 165,278	[1]	¥ 158,581	[1]	¥ 163,358
[1]	The amount includes ¥107,246 million and ¥101,498 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2019 and 2020, respectively. The tax effect of the net operating loss carryforwards is substantially offset by ¥88,294 million and ¥86,591 million, respectively, of valuation allowance as a result of considering all available evidence regarding sources of future taxable income including historical trends in taxable income in the preceding periods and forecasted taxable income.

Income Taxes (Net Operating Los

Income Taxes (Net Operating Losses Carryforwards by Expiration Date) (Detail) ¥ in Billions	Mar. 31, 2020JPY (¥)
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	¥ 637
2021
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0
2022
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0
2023
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	6
2024
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	3
2025
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0
2026 and thereafter
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	¥ 628	[1]
[1]	Including the net operating loss carryforwards which may be carried forward indefinitely in the United Kingdom.

Income Taxes (Roll-forward of U

Income Taxes (Roll-forward of Unrecognized Tax Benefits) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Operating Loss Carryforwards [Line Items]
Total unrecognized tax benefits at beginning of fiscal year	¥ 12,323	¥ 2,345	¥ 1,867
Gross amount of increases related to positions taken during prior years	199	9,550	224
Gross amount of increases related to positions taken during the current year	328	330	351
Amount of decreases related to settlements	(9,420)	0	0
Foreign exchange translation	(56)	98	(97)
Total unrecognized tax benefits at end of fiscal year	¥ 3,374	¥ 12,323	¥ 2,345

Pension and Other Employee Be_3

Pension and Other Employee Benefit Plans (Components of Net Periodic Costs of Severance Indemnities and Pension Plans) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Service cost-benefits earned during the fiscal year	¥ 45,697	¥ 43,698	¥ 43,649
Interest costs on projected benefit obligations	5,590	6,933	7,471
Expected return on plan assets	(40,551)	(38,518)	(34,916)
Amortization of prior service cost (benefits)	121	152	214
Amortization of net actuarial loss (gain)	(5,873)	(7,886)	411
Special termination benefits	9,793	2,929	3,960
Net periodic benefit cost	¥ 14,777	¥ 7,308	¥ 20,789

Pension and Other Employee Be_4

Pension and Other Employee Benefit Plans - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plans, costs recognized in respect of contributions to the plans	¥ 3,142	¥ 3,217	¥ 2,511
Amounts in accumulated other comprehensive income (loss) expected to be amortized as prior service cost or benefits over the next fiscal year	(409)
Amounts in accumulated other comprehensive income (loss) expected to be amortized as actuarial gain over the next fiscal year	(1,642)
Aggregated accumulated benefit obligations	¥ 1,571,296	¥ 1,590,818
Description of requirements for lump-sum severance indemnities	Employees with service in excess of one year are qualified to receive lump-sum severance indemnities.
Pension plan, contribution expected to be paid during the next fiscal year	¥ 50,000

Pension and Other Employee Be_5

Pension and Other Employee Benefit Plans (Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Loss) Before-Tax) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain (loss)	¥ (169,963)	¥ (21,300)
Amortization of net actuarial loss (gain)	(5,873)	(7,886)
Prior service benefits (cost)	(2,734)	(109)
Amortization of prior service cost (benefits)	121	152
Total recognized in other comprehensive income (loss) before-tax	¥ (178,449)	¥ (29,143)

Pension and Other Employee Be_6

Pension and Other Employee Benefit Plans (Weighted-Average Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost) (Detail)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Weighted-average assumptions used to determine benefit obligations at fiscal year end:
Discount rates	0.37%	0.34%	0.43%
Weighted-average assumptions used to determine net periodic benefit cost during the year:
Discount rates	0.34%	0.43%	0.47%
Expected rates of return on plan assets	1.68%	1.60%	1.58%
Minimum
Weighted-average assumptions used to determine benefit obligations at fiscal year end:
Rates of increase in future compensation levels	1.80%	1.80%	1.80%
Weighted-average assumptions used to determine net periodic benefit cost during the year:
Rates of increase in future compensation levels	1.80%	1.80%	1.80%
Maximum
Weighted-average assumptions used to determine benefit obligations at fiscal year end:
Rates of increase in future compensation levels	4.80%	4.80%	4.80%
Weighted-average assumptions used to determine net periodic benefit cost during the year:
Rates of increase in future compensation levels	4.80%	4.80%	4.80%

Pension and Other Employee Be_7

Pension and Other Employee Benefit Plans (Combined Funded Status and Amounts Recognized in Accompanying Consolidated Balance Sheets) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Change in benefit obligations:
Benefit obligations at beginning of fiscal year		¥ 1,590,818	¥ 1,559,356
Service cost		45,697	43,698	¥ 43,649
Interest cost		5,590	6,933	7,471
Plan participants' contributions		1,200	1,229
Amendments		2,734	109
Actuarial loss (gain)		4,507	49,085
Foreign exchange translation		(5,605)	(817)
Benefits paid		(52,902)	(52,618)
Lump-sum payments		(20,743)	(16,157)
Benefit obligations at end of fiscal year		1,571,296	1,590,818	1,559,356
Change in plan assets:
Fair value of plan assets at beginning of fiscal year		2,413,556	2,405,730
Actual return (negative return) on plan assets		(125,549)	66,652
Foreign exchange translation		(4,268)	(390)
Partial withdrawal of assets from employee retirement benefits trusts (Note)	[1]	0	(27,534)
Employer contributions		20,587	20,487
Plan participants' contributions		1,200	1,229
Benefits paid		(52,902)	(52,618)
Fair value of plan assets at end of fiscal year		2,252,624	2,413,556	¥ 2,405,730
Funded status		681,328	822,738
Amounts recognized in the consolidated balance sheets consist of:
Prepaid pension cost		711,981	850,472
Accrued pension liability		(30,653)	(27,734)
Net amount recognized		681,328	822,738
Amounts recognized in Accumulated other comprehensive income (loss) before-tax consist of:
Prior service benefits (cost)		(3,914)	(1,309)
Net actuarial gain (loss)		86,200	262,044
Net amount recognized		¥ 82,286	¥ 260,735
[1]	During the fiscal year ended March 31, 2019, a subsidiary of MHFG partially withdrew assets from employee retirement benefit trusts, which were established for the payment of employees’ severance pay and retirement pensions. Overall, the trusts remain in overfunded status as of March 31, 2019. No gains or losses have been recognized as a result of this transaction.

Pension and Other Employee Be_8

Pension and Other Employee Benefit Plans (Combined Funded Status and Amounts Recognized in Accompanying Consolidated Balance Sheets) (Parenthetical) (Detail)	12 Months Ended
	Mar. 31, 2020JPY (¥)
Defined Benefit Plan Disclosure [Line Items]
Gain (loss) recognized	¥ 0

Pension and Other Employee Be_9

Pension and Other Employee Benefit Plans (Plans with Projected Benefit Obligations in Excess of Plan Assets and Plans with Accumulated Benefit Obligations in Excess of Plan Assets) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	[1]	¥ 63,619	¥ 61,579
Fair value of plan assets		32,966	33,845
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		63,619	61,579
Fair value of plan assets		¥ 32,966	¥ 33,845
[1]	The plans with projected benefit obligations in excess of plan assets include those with accumulated benefit obligations in excess of plan assets.

Pension and Other Employee B_10

Pension and Other Employee Benefit Plans (Target Allocation for Plan Assets Excluding those of Employee Retirement Benefit Trusts) (Detail)	Mar. 31, 2020
Asset category
Plan assets	100.00%
General Account Assets
Asset category
Plan assets	11.00%	[1]
Other assets
Asset category
Plan assets	2.00%
Foreign | Equity securities
Asset category
Plan assets	25.00%
Foreign | Debt securities
Asset category
Plan assets	23.00%
Japan | Equity securities
Asset category
Plan assets	5.00%
Japan | Debt securities
Asset category
Plan assets	34.00%
[1]	General account of life insurance companies is a contract with life insurance companies which guarantees payments of principal and predetermined interest payments.

Pension and Other Employee B_11

Pension and Other Employee Benefit Plans (Fair Value of Plan Assets by Asset Category) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		¥ 2,252,624	¥ 2,413,556	¥ 2,405,730
Foreign | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		101,000	120,000
Foreign | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	4,000	5,000
Foreign | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	11,000	10,000
Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		195,000	184,000
Foreign | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		20,000	18,000
All Other | General account of life insurance companies
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[2]	111,000	111,000
All Other | Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		69,000	83,000
All Other | Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[3]	306,000	327,000
Japan | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	1,194,000	1,317,000
Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	14,000	15,000
Japan | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	9,000	10,000
Japan | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		196,000	190,000
Japan | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		23,000	24,000
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		1,757,000	1,895,000
Level 1 | Foreign | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		101,000	120,000
Level 1 | Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		188,000	178,000
Level 1 | All Other | Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[5]	68,000	79,000
Level 1 | Japan | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	1,194,000	1,317,000
Level 1 | Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	10,000	11,000
Level 1 | Japan | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		196,000	190,000
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		190,000	192,000
Level 2 | Foreign | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	4,000	5,000
Level 2 | Foreign | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	11,000	10,000
Level 2 | Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		7,000	6,000
Level 2 | Foreign | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		20,000	18,000
Level 2 | All Other | General account of life insurance companies
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[2]	111,000	111,000
Level 2 | All Other | Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		1,000	4,000
Level 2 | Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	4,000	4,000
Level 2 | Japan | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	9,000	10,000
Level 2 | Japan | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		¥ 23,000	¥ 24,000
[1]	These classes primarily include pension investment fund trusts. Investments in these classes are generally measured at fair value and can be redeemed within a short-term period upon request.
[2]	Investments in this class are measured at conversion value, which is equivalent to fair value.
[3]	In accordance with ASC 820, certain plan assets that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy.
[4]	This class represents equity securities held in the employee retirement benefit trusts of ¥1,317 billion and ¥1,194 billion carried at fair value at March 31, 2019 and 2020, respectively, which are well-diversified across industries.
[5]	Amounts primarily include cash and short-term assets carried at fair value.

Pension and Other Employee B_12

Pension and Other Employee Benefit Plans (Forecasted Benefit Payments Including Effect of Expected Future Service) (Detail) ¥ in Millions	Mar. 31, 2020JPY (¥)
Defined Benefit Plan Disclosure [Line Items]
2021	¥ 70,325
2022	70,623
2023	71,165
2024	72,469
2025	73,118
2026-2030	¥ 346,908

Pension and Other Employee B_13

Pension and Other Employee Benefit Plans (Fair Value of Plan Assets by Asset Category) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts		¥ 2,252,624	¥ 2,413,556	¥ 2,405,730
Equity securities | Common stocks | Japan
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts	[1]	1,194,000	1,317,000
Trust for Benefit of Employees | Equity securities | Common stocks | Japan
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts		¥ 1,194,000	¥ 1,317,000
[1]	This class represents equity securities held in the employee retirement benefit trusts of ¥1,317 billion and ¥1,194 billion carried at fair value at March 31, 2019 and 2020, respectively, which are well-diversified across industries.

Stock-based compensation - Addi

Stock-based compensation - Additional Information (Detail) ¥ / shares in Units, ¥ in Millions	12 Months Ended
	Mar. 31, 2020JPY (¥)¥ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation plan, exercise price per share	¥ 0
Cash deferred graded-vesting period	3 years
Compensation cost related to non-vested awards not yet recognized | ¥	¥ 1,175
Performance-based stock compensation, recognition period	1 year 6 months 21 days
MHFG Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation plan, shares of common stock to be issued or transferred upon exercise of each of the stock acquisition rights | shares | shares	1,000
Stock-based compensation plan, exercise price per share	¥ 1
Stock-based compensation plan, contractual term (in years)	20 years

Stock-Based Compensation (Summa

Stock-Based Compensation (Summary of Stock-Based Compensation Plan) (Detail) ¥ / shares in Units, ¥ in Millions	12 Months Ended
	Mar. 31, 2020JPY (¥)¥ / sharesshares
Number of shares
Outstanding at beginning of fiscal year | shares	4,245,000
Exercised during fiscal year | shares	2,968,000
Outstanding at end of fiscal year | shares	1,277,000
Exercisable at end of fiscal year | shares	0
Weighted-average exercise price
Outstanding at beginning of fiscal year | ¥ / shares	¥ 1
Exercised during fiscal year | ¥ / shares	1
Outstanding at end of fiscal year | ¥ / shares	1
Exercisable at end of fiscal year | ¥ / shares	¥ 0
Weighted-average remaining contractual term
Outstanding at end of fiscal year	13 years 10 months 28 days
Aggregate intrinsic value
Outstanding at end of fiscal year | ¥	¥ 157

Stock-Based Compensation-Schedu

Stock-Based Compensation-Schedule Of Stock-Based Compensation Expense (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Stock Compensation Plan I
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
The compensation cost recognized	¥ 917	¥ 713
Stock Compensation Plan II
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
The compensation cost recognized	¥ 1,247	¥ 1,287	¥ 868

Stock-based Compensation - Stoc

Stock-based Compensation - Stock Option Activity (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Stock Compensation Plan I
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of vested shares	¥ 917	¥ 713
Common stock shares acquired	917	713
Stock Compensation Plan II
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of vested shares	1,090	930
Common stock shares acquired	¥ 524	¥ 1,307

Stock-Based Compensation (Activ

Stock-Based Compensation (Activities Related to Performance-based Stock Compensation) (Detail) - Performance-based stock compensation - ¥ / shares	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Stock Compensation Plan I
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, Granted during fiscal year	5,748,997	3,770,065
Number of shares, Vested during fiscal year	5,748,997	3,770,065
Weighted-average grant-date fair value, Granted during fiscal year	¥ 159.59	¥ 189.24
Weighted-average grant-date fair value, Vested during fiscal year	¥ 159.59	¥ 189.24
Stock Compensation Plan II
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested at the beginning of the year	15,157,092	13,319,406
Number of shares, Granted during fiscal year	3,281,003	6,906,635
Number of shares, Vested during fiscal year	7,014,809	5,068,949
Nonvested at the end of the year	11,423,286	15,157,092
Weighted-average grant-date fair value, Nonvested at the beginning of the year	¥ 183.50	¥ 182.04
Weighted-average grant-date fair value, Granted during fiscal year	159.59	189.24
Weighted-average grant-date fair value, Vested during fiscal year	182.07	187.48
Weighted-average grant-date fair value, Nonvested at the ending of the year	¥ 177.51	¥ 183.50

Derivative Financial Instrume_3

Derivative Financial Instruments (Summary of Notional and Fair Value Amounts of Derivative Instruments Outstanding) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2020	Mar. 31, 2019
Derivatives, Fair Value [Line Items]
Notional amount	[1]	¥ 1,320,665	¥ 1,227,208
Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	1,123,546	1,052,267
Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	185,359	166,383
Equity-related contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	6,684	5,181
Credit-related contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	4,676	2,939
Other contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	400	438
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	10,536	7,904
Fair value of derivative payables	[2]	10,021	7,541
Not Designated as Hedging Instrument | Interest rate contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	7,232	5,786
Fair value of derivative payables	[2]	6,788	5,610
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	2,926	1,959
Fair value of derivative payables	[2]	2,899	1,758
Not Designated as Hedging Instrument | Equity-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	310	125
Fair value of derivative payables	[2]	266	142
Not Designated as Hedging Instrument | Credit-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	30	18
Fair value of derivative payables	[2]	29	17
Not Designated as Hedging Instrument | Other contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	38	16
Fair value of derivative payables	[2]	¥ 39	¥ 14
[1]	Notional amount includes the sum of gross long and gross short third-party contracts.
[2]	Derivative receivables and payables are recorded in Trading account assets and Trading account liabilities, respectively.

Derivative Financial Instrume_4

Derivative Financial Instruments - Additional Information (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Derivative [Line Items]
Cash collateral provided and not offset against derivative positions and included in Other assets	¥ 1,246,026	¥ 856,439
Cash collateral accepted and not offset against derivative positions and included in Other liabilities	¥ 846,426	¥ 589,411

Derivative Financial Instrume_5

Derivative Financial Instruments (Summary of Gains and Losses Information Related to Fair Value Hedges) (Detail) ¥ in Millions	12 Months Ended
	Mar. 31, 2018JPY (¥)
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income- Derivatives	¥ (23,832)
Gains (losses) recorded in income- Hedged items	19,631
Gains (losses) recorded in income- Net gain (loss) excluded from assessment of effectiveness	(4,201)
Equity-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income- Derivatives	(23,832)
Gains (losses) recorded in income- Hedged items	19,631
Gains (losses) recorded in income- Net gain (loss) excluded from assessment of effectiveness	¥ (4,201)

Derivative Financial Instrume_6

Derivative Financial Instruments (Summary of Gains and Losses Information Related to Net Investment Hedges) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in OCI	¥ 418	¥ 7,512	¥ 60
Financial instruments hedging foreign exchange risk
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in OCI	¥ 418	¥ 7,512	¥ 60

Derivative Financial Instrume_7

Derivative Financial Instruments (Summary of Gains and Losses Information Related to Net Investment Hedges) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Financial instruments hedging foreign exchange risk
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income reclassified to earnings	¥ (1,336)	¥ 186	¥ 0

Derivative Financial Instrume_8

Derivative Financial Instruments (Summary of Gains and Losses on Derivatives not Designated or Qualifying as Hedges) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 481,016	¥ 169,943	¥ (93,321)
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		388,289	127,242	(63,260)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		(111,920)	6,748	61,046
Equity-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[1]	217,744	37,875	(94,607)
Credit-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[2]	8,046	(467)	(2,830)
Other contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ (21,143)	¥ (1,455)	¥ 6,330
[1]	The net gains (losses) excluded from the assessment of the effectiveness of fair value hedges is not included in the above table.
[2]	Amounts include the net gains (losses) of ¥(754) million, ¥(736) million and ¥2,838 million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2018, 2019 and 2020, respectively.

Derivative Financial Instrume_9

Derivative Financial Instruments (Summary of Gains and Losses on Derivatives not Designated or Qualifying as Hedges) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 481,016	¥ 169,943	¥ (93,321)
Credit-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[1]	8,046	(467)	(2,830)
Credit-related contracts | Loans related to credit derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 2,838	¥ (736)	¥ (754)
[1]	Amounts include the net gains (losses) of ¥(754) million, ¥(736) million and ¥2,838 million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2018, 2019 and 2020, respectively.

Derivative Financial Instrum_10

Derivative Financial Instruments (Summary of Notional and Fair Value Amounts of Credit Derivatives) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Credit protection written
Credit Derivatives [Line Items]
Notional amount	¥ 1,816	¥ 1,465
Fair value	(5)	15
Credit protection written | Investment grade
Credit Derivatives [Line Items]
Notional amount	1,400	1,266
Fair value	(5)	12
Credit protection written | Non-investment grade
Credit Derivatives [Line Items]
Notional amount	416	199
Fair value	0	3
Credit protection purchased
Credit Derivatives [Line Items]
Notional amount	3,028	1,628
Fair value	¥ 6	¥ (14)

Derivative Financial Instrum_11

Derivative Financial Instruments (Maximum Potential Amount of Future Payments for Credit Protection Written by Expiration Period) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Credit Derivatives [Line Items]
Maximum payout/Notional amount	¥ 1,816	¥ 1,465
One year or less
Credit Derivatives [Line Items]
Maximum payout/Notional amount	270	326
After one year through five years
Credit Derivatives [Line Items]
Maximum payout/Notional amount	1,368	1,057
After five years
Credit Derivatives [Line Items]
Maximum payout/Notional amount	¥ 178	¥ 82

Derivative Financial Instrum_12

Derivative Financial Instruments (Quantitative Information about Derivative Instruments with Credit-risk-related Contingent Features) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Credit Derivatives [Line Items]
Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions	¥ 888	¥ 511
Collateral provided to counterparties in the normal course of business	818	489
Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered	¥ 70	¥ 22

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Commitments And Contingencies Disclosure [Line Items]
Carrying amount of guarantees and similar obligations	¥ 521	¥ 109
Carrying amounts of derivatives that are deemed to guarantees	502	90
Off-balance Sheet instruments
Commitments And Contingencies Disclosure [Line Items]
Allowance for losses on off-balance-sheet instruments	¥ 99	¥ 80

Commitments and Contingencies_2

Commitments and Contingencies (Summary of Maximum Potential Amount of Future Payments under Guarantees) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	¥ 2,456	¥ 2,307
Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	301	289
Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	110	145
Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	2,314	2,324
Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	59	65
Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	446	362
Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	21,756	14,170
One year or less | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	1,511	1,265
One year or less | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	204	164
One year or less | Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	22	91
One year or less | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	1,925	1,447
One year or less | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	80	61
One year or less | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	11,045	5,807
After one year through five years | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	735	878
After one year through five years | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	34	46
After one year through five years | Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	88	54
After one year through five years | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	319	834
After one year through five years | Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	42	47
After one year through five years | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	201	148
After one year through five years | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	7,951	6,434
After five years | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	210	164
After five years | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	63	79
After five years | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	70	43
After five years | Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	17	18
After five years | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	165	153
After five years | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	¥ 2,760	¥ 1,929

Commitments and Contingencies_3

Commitments and Contingencies (Summary of Maximum Potential Amount of Future Payments of Certain Guarantees Classified Based on Internal Ratings) (Detail) - Performance guarantees, Guarantees on loans, Guarantees on securities and Other guarantees - JPY (¥) ¥ in Billions		Mar. 31, 2020	Mar. 31, 2019
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount		¥ 5,181	¥ 5,065
Investment grade
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	[1]	4,233	4,124
Non-investment grade
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount		¥ 948	¥ 941
[1]	Investment grade in the internal rating scale generally corresponds to BBB- or above in the external rating scale.

Commitments and Contingencies_4

Commitments and Contingencies (Summary of Contractual Amounts with Regard to Undrawn Commitments) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2020	Mar. 31, 2019
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments		¥ 77,323	¥ 77,635
Commitments to Extend Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments	[1]	76,633	76,857
Commercial letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments		¥ 690	¥ 778
[1]	Commitments to extend credit include commitments to invest in securities.

Commitments and contingencies_5

Commitments and contingencies - Schedule Of Balance Sheet Information Related to Operating Lease (Detail) ¥ in Millions	Mar. 31, 2020JPY (¥)
Commitments and Contingencies Disclosure [Abstract]
ROU assets	¥ 613,068	[1],[2]
Lease liabilities	¥ 627,250	[1],[2]
Weighted average:
Remaining lease term	15 years 8 months 12 days
Discount rate	0.55%
[1]	ROU assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets.
[2]	ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 on April 1, 2019. See Note 1 “Basis of presentation and summary of significant accounting policies” and Note 2 “Issued accounting pronouncements” for further information.

Commitments and contingencies_6

Commitments and contingencies - Schedule Of Operating Lease Cost And Supplemental Cash Flow Information (Detail) ¥ in Millions	12 Months Ended
	Mar. 31, 2020JPY (¥)
Commitments and Contingencies Disclosure [Abstract]
Lease cost	¥ 126,840
ROU assets obtained in exchange for new lease liabilities	60,047
Operating cash flows	¥ 102,066

Commitments and contingencies_7

Commitments and contingencies - Schedule Of Operating Lease Cost And Supplemental Cash Flow Information (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Rental expense	¥ 115,239	¥ 117,270

Commitments and contingencies_8

Commitments and contingencies - Schedule Of Future Lease Payments Under Operating Leases (Detail) ¥ in Millions	Mar. 31, 2020JPY (¥)
Commitments and Contingencies Disclosure [Abstract]
2021	¥ 93,997
2022	68,268
2023	54,377
2024	47,608
2025	41,539
2026 and thereafter	346,741
Total lease payments	652,530
Amount representing interest	25,280
Total lease liabilities for operating leases	¥ 627,250	[1],[2]
[1]	ROU assets and lease liabilities are included in Other assets and Other liabilities, respectively, on the consolidated balance sheets.
[2]	ROU assets and lease liabilities were initially recognized in connection with the adoption of ASU No.2016-02 on April 1, 2019. See Note 1 “Basis of presentation and summary of significant accounting policies” and Note 2 “Issued accounting pronouncements” for further information.

Variable Interest Entities an_3

Variable Interest Entities and Securitizations (Consolidated Assets of Consolidated VIEs as well as Total Assets and Maximum Exposure to Loss for Significant Unconsolidated VIEs) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	¥ 5,815	¥ 6,048
Significant unconsolidated VIEs- Total assets	2,376	1,350
Significant unconsolidated VIEs- Maximum exposure to loss	521	418
Asset-backed commercial paper/loan programs
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	2,160	2,249
Asset-backed securitizations
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	572	571
Significant unconsolidated VIEs- Total assets	77	70
Significant unconsolidated VIEs- Maximum exposure to loss	7	8
Investments in securitization products
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	370	372
Investment funds
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	2,694	2,836
Significant unconsolidated VIEs- Total assets	2,299	1,280
Significant unconsolidated VIEs- Maximum exposure to loss	514	410
Trust arrangements and other
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	¥ 19	¥ 20

Variable Interest Entities an_4

Variable Interest Entities and Securitizations (Carrying Amounts and Classification of Assets and Liabilities on Consolidated Balance Sheets that Relate to Variable Interests in Significant Unconsolidated VIEs) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Assets on balance sheets related to unconsolidated VIEs:
Trading account assets		¥ 28,092,871	¥ 21,018,230
Loans		87,087,233	82,492,742
Total assets		211,218,760	197,611,195	¥ 204,255,600
Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs:
Payables under securities lending transactions		1,423,638	1,797,737
Trading account liabilities		12,416,785	10,120,968
Total		202,043,136	188,109,702
Maximum exposure to loss		521,000	418,000
Unconsolidated VIEs
Assets on balance sheets related to unconsolidated VIEs:
Trading account assets		108,000	104,000
Investments		267,000	168,000
Loans		55,000	71,000
Total assets		430,000	343,000
Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs:
Payables under securities lending transactions		47,000	47,000
Trading account liabilities		2,000	1,000
Total		49,000	48,000
Maximum exposure to loss	[1]	¥ 521,000	¥ 418,000
[1]	This represents the maximum amount the Group could possibly be required to record in its consolidated statements of income associated with on-balance-sheet exposures and off-balance-sheet liabilities such as undrawn commitments.

Variable Interest Entities an_5

Variable Interest Entities and Securitizations - Additional Information (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Variable Interest Entity [Line Items]
Long-term debt	¥ 10,346,152	¥ 11,529,400
Noncontrolling interests	663,259	774,974
Consolidated VIEs
Variable Interest Entity [Line Items]
Noncontrolling interests	541,000	621,000
Debt Instrument [Member]
Variable Interest Entity [Line Items]
Long-term debt	356,000	681,000
Assets associated with securitization transactions
Variable Interest Entity [Line Items]
Transferred assets continue to be carried on the consolidated balance sheets	176,000	207,000
Assets associated with loan participation transactions
Variable Interest Entity [Line Items]
Transferred assets continue to be carried on the consolidated balance sheets	¥ 153,000	¥ 143,000

Summary of Noninterest Income (

Summary of Noninterest Income (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Fee and commission income		¥ 867,885	¥ 853,290	¥ 865,711
Foreign exchange gains (losses)—net	[1],[2]	44,345	93,577	91,793
Trading account gains (losses)—net	[3]	745,692	328,841	236,982
Investment gains (losses)—net:
Debt securities	[2]	31,032	(3,842)	7,757
Equity securities	[2]	(557,391)	(155,947)	289,400
Equity in earnings (losses) of equity method investees—net	[2]	34,012	29,172	24,342
Gains on disposal of premises and equipment	[2]	2,583	5,145	8,225
Other noninterest income	[3],[4]	139,582	72,135	80,453
Total noninterest income		1,307,740	1,222,371	1,604,663
Securities related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	139,124	145,270	180,122
Banking
Disaggregation of Revenue [Line Items]
Fee and commission income	[3]	157,420	152,283	156,426
Correspondent clearing
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	112,275	110,382	110,054
Investment advisory, management and administrative service
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	98,720	97,852	100,765
Fiduciary and trust
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	129,298	124,843	121,808
Agency business
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	31,879	36,466	37,397
Guarantee related business
Disaggregation of Revenue [Line Items]
Fee and commission income	[2]	28,974	28,582	28,258
Financial service, other
Disaggregation of Revenue [Line Items]
Fee and commission income	[5]	170,195	157,612	130,881
Financial service
Disaggregation of Revenue [Line Items]
Fee and commission income		¥ 867,885	¥ 853,290	¥ 865,711
[1]	Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.
[2]	These amounts are revenues from contracts that do not meet the scope of ASC 606.
[3]	Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606.
[4]	These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 27 “Fair value” for further details.
[5]	These amounts are revenues from contracts within the scope of ASC 606, “Revenue from contracts with customers ” (“ASC 606”).

Noninterest Income - Additional

Noninterest Income - Additional Information (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Other Revenues [Line Items]
Lending fees		¥ 143,000
Trust fees		54,000	¥ 51,000
Fees related to trust business		75,000	74,000
Trading account gains (losses)—net	[1]	745,692	328,841	¥ 236,982
Other noninterest income	[1],[2]	139,582	72,135	¥ 80,453
Revenue from contracts with customers ("ASC 606")
Other Revenues [Line Items]
Deposit fees		14,000
Trading account gains (losses)—net		60,000	68,000
Other noninterest income		¥ 24,000	¥ 26,000
[1]	Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606.
[2]	These amounts include the net unrealized gains resulting from changes in fair values of structured notes that contain embedded derivatives. See Note 27 “Fair value” for further details.

Trading Account Gains and Los_3

Trading Account Gains and Losses (Net Trading Gains and Losses) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net	[1]	¥ 745,692	¥ 328,841	¥ 236,982
Foreign exchange gains (losses)—net	[2],[3]	44,345	93,577	91,793
Net trading gains (losses)		790,037	422,418	328,775
Interest rate contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net		388,289	127,242	(63,260)
Foreign exchange contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net	[4]	(111,920)	6,748	61,046
Equity-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net	[5]	217,744	37,875	(98,807)
Credit-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net	[6]	5,208	269	(2,076)
Other contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net		(21,143)	(1,455)	6,330
Trading securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)—net		¥ 267,514	¥ 158,162	¥ 333,749
[1]	Part of these amounts are considered to be revenues from contracts that are within the scope of ASC 606.
[2]	Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments. Amounts on derivative instruments include gains and losses on forward foreign exchange contracts and currency options. Amounts on nonderivative instruments include translation gains and losses related to foreign currency-denominated debt securities reported as Trading securities.
[3]	These amounts are revenues from contracts that do not meet the scope of ASC 606.
[4]	Amounts include gains and losses on currency swaps.
[5]	The net gains (losses) excluded from the assessment of the effectiveness of fair value hedges is included in the above table.
[6]	Amounts do not include the net gains (losses) of ¥(754) million, ¥(736) million and ¥2,838 million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2018, 2019 and 2020, respectively. The net gains (losses) is recorded in Other noninterest income (expenses).

Trading Account Gains and Los_4

Trading Account Gains and Losses (Net Trading Gains and Losses) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income		¥ 481,016	¥ 169,943	¥ (93,321)
Credit-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income	[1]	8,046	(467)	(2,830)
Credit-related contracts | Loans related to credit derivatives
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income		¥ 2,838	¥ (736)	¥ (754)
[1]	Amounts include the net gains (losses) of ¥(754) million, ¥(736) million and ¥2,838 million on the credit derivatives economically managing the credit risk of loans during the fiscal years ended March 31, 2018, 2019 and 2020, respectively.

Fair Value - Additional Informa

Fair Value - Additional Information (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of assets transferred into Level 3	¥ 1
Fair value of assets transferred out of Level 3	1
Carrying amounts of other equity interests of which fair value is not readily determinable	420	¥ 212
Senior borrowings and bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
The differences between the aggregate fair value and aggregate unpaid principal balance of the notes for which the fair value option has been elected	112	21
Net unrealized gains (losses) resulting from changes in fair values of the notes	¥ 56	(17)
Investment funds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Underlying assets, estimated remaining liquidation period	10 years
Long-term debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of liabilities transferred out of Level 3	¥ 8
Fair value of liabilities transferred into Level 3	77	7
Derived
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of liabilities transferred out of Level 3	¥ 1
Available-for-sale securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of assets transferred into Level 3		61
Fair value of assets transferred out of Level 3		¥ 42

Fair Value (Summary of Assets a

Fair Value (Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis, Including Fair Value Option Elected) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Assets:
Available-for-sale securities		¥ 19,112,952	¥ 18,133,916
Liabilities:
Long-term debt		2,537,082	2,433,294
Fair Value, Measurements, Recurring
Assets:
Equity securities with readily determinable fair values		2,765,000	3,768,000
Equity securities measured at net asset value	[1]	72,000	53,000
Other investments		39,000	35,000
Total assets measured at fair value		50,081,000	43,007,000
Liabilities:
Trading securities sold, not yet purchased		2,395,000	2,580,000
Long-term debt	[2]	2,537,000	2,433,000
Total liabilities measured at fair value		14,953,000	12,554,000
Fair Value, Measurements, Recurring | Trading Account Asset
Assets:
Securities measured at net asset value	[1],[3]	462,000	631,000
Fair Value, Measurements, Recurring | Interest rate contracts
Assets:
Assets, derivatives		7,232,000	5,786,000
Liabilities:
Liabilities, derivatives		6,788,000	5,610,000
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets:
Assets, derivatives		2,926,000	1,959,000
Liabilities:
Liabilities, derivatives		2,899,000	1,758,000
Fair Value, Measurements, Recurring | Equity-related contracts
Assets:
Assets, derivatives		310,000	125,000
Liabilities:
Liabilities, derivatives		266,000	142,000
Fair Value, Measurements, Recurring | Credit-related contracts
Assets:
Assets, derivatives		30,000	18,000
Liabilities:
Liabilities, derivatives		29,000	17,000
Fair Value, Measurements, Recurring | Other contracts
Assets:
Assets, derivatives		38,000	16,000
Liabilities:
Liabilities, derivatives		39,000	14,000
Fair Value, Measurements, Recurring | Japanese government bonds
Assets:
Assets, trading securities	[3]	1,538,000	1,862,000
Available-for-sale securities		12,603,000	11,897,000
Fair Value, Measurements, Recurring | Japanese local government bonds
Assets:
Assets, trading securities	[3]	170,000	134,000
Available-for-sale securities		273,000	210,000
Fair Value, Measurements, Recurring | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	5,041,000	1,207,000
Available-for-sale securities		935,000	1,009,000
Fair Value, Measurements, Recurring | Other foreign government bonds
Assets:
Assets, trading securities	[3]	1,675,000	2,970,000
Available-for-sale securities		1,411,000	1,342,000
Fair Value, Measurements, Recurring | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	3,390,000	1,041,000
Available-for-sale securities		505,000	544,000
Fair Value, Measurements, Recurring | Residential mortgage-backed securities
Assets:
Assets, trading securities	[3]	10,000	11,000
Available-for-sale securities		84,000	101,000
Fair Value, Measurements, Recurring | Commercial mortgage-backed securities
Assets:
Available-for-sale securities		615,000	500,000
Fair Value, Measurements, Recurring | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[3]	1,036,000	1,047,000
Fair Value, Measurements, Recurring | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3],[4]	2,554,000	2,886,000
Fair Value, Measurements, Recurring | Equity securities
Assets:
Assets, trading securities	[3]	1,680,000	1,325,000
Fair Value, Measurements, Recurring | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		1,835,000	1,749,000
Fair Value, Measurements, Recurring | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		852,000	781,000
Fair Value, Measurements, Recurring | Level 1
Assets:
Equity securities with readily determinable fair values		2,670,000	3,633,000
Total assets measured at fair value		24,590,000	22,753,000
Liabilities:
Trading securities sold, not yet purchased		1,880,000	2,380,000
Total liabilities measured at fair value		2,243,000	2,512,000
Fair Value, Measurements, Recurring | Level 1 | Interest rate contracts
Assets:
Assets, derivatives		153,000	36,000
Liabilities:
Liabilities, derivatives		163,000	38,000
Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Assets:
Assets, derivatives		9,000	9,000
Liabilities:
Liabilities, derivatives		8,000	11,000
Fair Value, Measurements, Recurring | Level 1 | Equity-related contracts
Assets:
Assets, derivatives		169,000	58,000
Liabilities:
Liabilities, derivatives		186,000	82,000
Fair Value, Measurements, Recurring | Level 1 | Other contracts
Assets:
Assets, derivatives		3,000	2,000
Liabilities:
Liabilities, derivatives		6,000	1,000
Fair Value, Measurements, Recurring | Level 1 | Japanese government bonds
Assets:
Assets, trading securities	[3]	1,516,000	1,829,000
Available-for-sale securities		11,950,000	10,902,000
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	4,580,000	1,069,000
Available-for-sale securities		935,000	1,009,000
Fair Value, Measurements, Recurring | Level 1 | Other foreign government bonds
Assets:
Assets, trading securities	[3]	1,128,000	2,417,000
Available-for-sale securities		436,000	456,000
Fair Value, Measurements, Recurring | Level 1 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3],[4]	41,000	36,000
Fair Value, Measurements, Recurring | Level 1 | Equity securities
Assets:
Assets, trading securities	[3]	1,000,000	1,297,000
Fair Value, Measurements, Recurring | Level 2
Assets:
Equity securities with readily determinable fair values		95,000	135,000
Total assets measured at fair value		22,712,000	17,629,000
Liabilities:
Trading securities sold, not yet purchased		515,000	199,000
Long-term debt	[2]	1,916,000	1,778,000
Total liabilities measured at fair value		12,008,000	9,358,000
Fair Value, Measurements, Recurring | Level 2 | Interest rate contracts
Assets:
Assets, derivatives		7,070,000	5,729,000
Liabilities:
Liabilities, derivatives		6,611,000	5,564,000
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Assets:
Assets, derivatives		2,900,000	1,927,000
Liabilities:
Liabilities, derivatives		2,890,000	1,746,000
Fair Value, Measurements, Recurring | Level 2 | Equity-related contracts
Assets:
Assets, derivatives		125,000	63,000
Liabilities:
Liabilities, derivatives		47,000	51,000
Fair Value, Measurements, Recurring | Level 2 | Credit-related contracts
Assets:
Assets, derivatives		22,000	16,000
Liabilities:
Liabilities, derivatives		19,000	16,000
Fair Value, Measurements, Recurring | Level 2 | Other contracts
Assets:
Assets, derivatives		11,000	4,000
Liabilities:
Liabilities, derivatives		10,000	4,000
Fair Value, Measurements, Recurring | Level 2 | Japanese government bonds
Assets:
Assets, trading securities	[3]	22,000	33,000
Available-for-sale securities		653,000	995,000
Fair Value, Measurements, Recurring | Level 2 | Japanese local government bonds
Assets:
Assets, trading securities	[3]	170,000	134,000
Available-for-sale securities		273,000	210,000
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	461,000	138,000
Fair Value, Measurements, Recurring | Level 2 | Other foreign government bonds
Assets:
Assets, trading securities	[3]	547,000	553,000
Available-for-sale securities		975,000	886,000
Fair Value, Measurements, Recurring | Level 2 | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	3,390,000	1,041,000
Available-for-sale securities		505,000	544,000
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage-backed securities
Assets:
Available-for-sale securities		53,000	61,000
Fair Value, Measurements, Recurring | Level 2 | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[3]	1,036,000	1,047,000
Fair Value, Measurements, Recurring | Level 2 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3],[4]	1,398,000	1,806,000
Fair Value, Measurements, Recurring | Level 2 | Equity securities
Assets:
Assets, trading securities	[3]	650,000
Fair Value, Measurements, Recurring | Level 2 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		1,678,000	1,629,000
Fair Value, Measurements, Recurring | Level 2 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		678,000	678,000
Fair Value, Measurements, Recurring | Level 3
Assets:
Other investments		39,000	35,000
Total assets measured at fair value		2,245,000	1,941,000
Liabilities:
Trading securities sold, not yet purchased			1,000
Long-term debt	[2]	621,000	655,000
Total liabilities measured at fair value		702,000	684,000
Fair Value, Measurements, Recurring | Level 3 | Interest rate contracts
Assets:
Assets, derivatives		9,000	21,000
Liabilities:
Liabilities, derivatives		14,000	8,000
Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Assets:
Assets, derivatives		17,000	23,000
Liabilities:
Liabilities, derivatives		1,000	1,000
Fair Value, Measurements, Recurring | Level 3 | Equity-related contracts
Assets:
Assets, derivatives		16,000	4,000
Liabilities:
Liabilities, derivatives		33,000	9,000
Fair Value, Measurements, Recurring | Level 3 | Credit-related contracts
Assets:
Assets, derivatives		8,000	2,000
Liabilities:
Liabilities, derivatives		10,000	1,000
Fair Value, Measurements, Recurring | Level 3 | Other contracts
Assets:
Assets, derivatives		24,000	10,000
Liabilities:
Liabilities, derivatives		23,000	9,000
Fair Value, Measurements, Recurring | Level 3 | Residential mortgage-backed securities
Assets:
Assets, trading securities	[3]	10,000	11,000
Available-for-sale securities		31,000	40,000
Fair Value, Measurements, Recurring | Level 3 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities		615,000	500,000
Fair Value, Measurements, Recurring | Level 3 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3],[4]	1,115,000	1,044,000
Fair Value, Measurements, Recurring | Level 3 | Equity securities
Assets:
Assets, trading securities	[3]	30,000	28,000
Fair Value, Measurements, Recurring | Level 3 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		157,000	120,000
Fair Value, Measurements, Recurring | Level 3 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		¥ 174,000	¥ 103,000
[1]	In accordance with ASC 820, certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented for these classes of assets are intended to permit the reconciliation of the fair value hierarchy to the amounts presented in the statements of financial position. The amounts of unfunded commitments related to these investments at March 31, 2019 and 2020 were ¥37 billion and ¥47 billion, respectively.
[2]	Amounts represent items for which the Group elected the fair value option or for which it applied the practicability exception.
[3]	Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option.
[4]	The amount includes CLO and convertible bonds, which are classified in Level 3.

Fair Value (Summary of Assets_2

Fair Value (Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis, Including Fair Value Option Elected) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unfunded commitments	¥ 47	¥ 37

Fair Value (Reconciliation for

Fair Value (Reconciliation for All Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3)) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers into Level 3		¥ 1
Transfers out of level 3		(1)
Other investments
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		35	¥ 38
Gains (losses) in Earnings	[1]		5
Purchases			13
Sales			(6)
Settlements			(15)
Ending Balance			35
Change in unrealized gain (losses) still held	[2]		(2)
Trading securities sold, not yet purchased
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		1	4
Gains (losses) in Earnings	[3]		1
Purchases		(18)	(35)
Sales		17	33
Ending Balance			1
Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		655	561
Gains (losses) in Earnings		53	(6)	[4]
Gains (losses) in OCI		17	10	[5]
Transfers into Level 3		77	7
Transfers out of level 3		(8)
Issuances		312	192
Settlements		(345)	(101)
Ending Balance		621	655
Change in unrealized gain (losses) still held		79	5	[2]
Trading securities | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		11	12
Settlements		(1)	(1)
Ending Balance		10	11
Trading securities | Corporate bonds and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		1,044	1,013
Gains (losses) in Earnings		(52)	1	[3]
Purchases		802	762
Sales		(297)	(378)
Settlements		(382)	(354)
Ending Balance		1,115	1,044
Change in unrealized gain (losses) still held		(52)	8	[2]
Trading securities | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		28	23
Gains (losses) in Earnings		(1)	1	[3]
Purchases		6	7
Sales		(2)	(3)
Settlements		(1)
Ending Balance		30	28
Change in unrealized gain (losses) still held		(1)	(1)	[2]
Derivative financial instruments assets | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[6]	13	21
Gains (losses) in Earnings		(6)	(11)	[3],[6]
Transfers into Level 3		1
Settlements		(13)	3	[6]
Ending Balance		(5)	13	[6]
Change in unrealized gain (losses) still held		(16)	(5)	[2],[6]
Derivative financial instruments assets | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[6]	22	12
Gains (losses) in Earnings		(4)	15	[3],[6]
Settlements		(2)	(5)	[6]
Ending Balance		16	22	[6]
Change in unrealized gain (losses) still held		(3)	14	[2],[6]
Derivative financial instruments assets | Equity-related contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[6]	(5)	4
Gains (losses) in Earnings		(8)	(15)	[3],[6]
Settlements		(4)	6	[6]
Ending Balance		(17)	(5)	[6]
Change in unrealized gain (losses) still held		(10)	3	[2],[6]
Derivative financial instruments assets | Credit-related contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[6]	1	1
Gains (losses) in Earnings		(2)	(2)	[3],[6]
Transfers into Level 3		(1)
Transfers out of level 3		(1)
Settlements		1	2	[6]
Ending Balance		(2)	1	[6]
Change in unrealized gain (losses) still held		(1)	1	[2],[6]
Derivative financial instruments assets | Other contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[6]	1
Gains (losses) in Earnings		2	1	[3],[6]
Settlements		(2)
Ending Balance		1	1	[6]
Change in unrealized gain (losses) still held		1	1	[2],[6]
Available-for-sale securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers into Level 3			61
Transfers out of level 3			(42)
Available-for-sale securities | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		40	54
Purchases		3
Settlements		(12)	(14)
Ending Balance		31	40
Available-for-sale securities | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		500	441
Gains (losses) in OCI		1	1	[5]
Purchases		201	144
Sales		(77)	(72)
Settlements		(10)	(14)
Ending Balance		615	500
Available-for-sale securities | Japanese corporate bonds and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		120	163
Gains (losses) in Earnings		2	37	[1]
Gains (losses) in OCI	[5]		(33)
Purchases		106	29
Sales			(7)
Settlements		(71)	(69)
Ending Balance		157	120
Change in unrealized gain (losses) still held	[2]		19
Available-for-sale securities | Foreign corporate bonds and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		103	80
Gains (losses) in OCI		(11)	(1)	[5]
Transfers into Level 3			61
Transfers out of level 3			(42)
Purchases		94	27
Settlements		(12)	(22)
Ending Balance		174	103
Available-for-sale securities | Other investments
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		35
Gains (losses) in Earnings		3
Purchases		15
Settlements		(14)
Ending Balance		39	¥ 35
Change in unrealized gain (losses) still held		¥ 3
[1]	Gains (losses) in Earnings are reported in Investment gains (losses)—net.
[2]	Amounts represent total gains or losses recognized in earnings during the period. These gains or losses were attributable to the change in fair value relating to assets and liabilities classified as Level 3 that were still held at March 31, 2019 and 2020.
[3]	Gains (losses) in Earnings are reported in Trading account gains (losses)—net, Foreign exchange gains (losses)—net or Other noninterest income (expenses).
[4]	Gains (losses) in Earnings are reported in Other noninterest income (expenses).
[5]	Gains (losses) in OCI are reported in Other comprehensive income (loss).
[6]	Total Level 3 derivative exposures have been netted on the table for presentation purposes only.

Fair Value (Quantitative Inform

Fair Value (Quantitative Information about Significant Unobservable Inputs Related to Material Classes of Level 3 Assets and Liabilities) (Detail) ¥ in Millions		Mar. 31, 2020JPY (¥)BasisPoint	Mar. 31, 2019JPY (¥)BasisPoint
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt | ¥		¥ 2,537,082	¥ 2,433,294
Available For Sale And Trading Securities | Residential mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities | ¥		41,000	51,000
Available For Sale And Trading Securities | Commercial mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities | ¥		615,000	500,000
Available For Sale And Trading Securities | Corporate bonds and other debt securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities | ¥		1,446,000	1,267,000
Derivative Financial Instruments | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments | ¥		(5,000)	13,000
Derivative Financial Instruments | Foreign exchange contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments | ¥		16,000	22,000
Derivative Financial Instruments | Equity-related contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments | ¥		(17,000)	(5,000)
Derivative Financial Instruments | Credit-related contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments | ¥		(2,000)	1,000
Long-term debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt | ¥		¥ 621,000	¥ 655,000
Minimum | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		4	4
Minimum | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	13	22
Minimum | Measurement Input, Default Rate [Member] | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		0
Minimum | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities			0
Minimum | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	0	2
Minimum | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Interest rate contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2]	0	0	[3]
Minimum | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[3]	0	0
Minimum | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	0	0
Minimum | Measurement Input, Default Rate [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	0	0
Minimum | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		100	100
Minimum | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	10	69
Minimum | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		5	18
Minimum | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	61	48
Minimum | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		7	9
Minimum | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[4]	5	4
Minimum | Measurement Input, IR - IR correlation [Member] | Derivative Financial Instruments | Interest rate contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	23	23
Minimum | Measurement Input, IR - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	23	23
Minimum | Measurement Input, FX - IR correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	(37)	9
Minimum | Measurement Input, FX - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	(37)	9
Minimum | Measurement Input, FX - FX correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	56	63
Minimum | Measurement Input, FX - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	56	63
Minimum | Measurement Input, Equity - IR correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	25	25
Minimum | Measurement Input, Equity - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	25	25
Minimum | Measurement Input, Equity - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	(33)	55
Minimum | Measurement Input, Equity volatility [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	13	5
Minimum | Measurement Input, Equity volatility [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	15	5
Minimum | Measurement Input, Credit correlation [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	30	29
Minimum | Measurement Input, Credit correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	15	20
Minimum | Measurement Input, Equity correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	0	40
Minimum | Measurement Input, Equity correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	0	12
Maximum | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		16	19
Maximum | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	21	22
Maximum | Measurement Input, Default Rate [Member] | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		1
Maximum | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities			1
Maximum | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	2	2
Maximum | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Interest rate contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[3]	63	63
Maximum | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[2],[3]	63	63
Maximum | Measurement Input, Default Rate [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	15	5
Maximum | Measurement Input, Default Rate [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	12	4
Maximum | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		100	100
Maximum | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	70	69
Maximum | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		170	170
Maximum | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[1]	1,160	1,173
Maximum | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities		185	161
Maximum | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[4]	1,528	1,063
Maximum | Measurement Input, IR - IR correlation [Member] | Derivative Financial Instruments | Interest rate contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	100	100
Maximum | Measurement Input, IR - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	100	100
Maximum | Measurement Input, FX - IR correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	49	55
Maximum | Measurement Input, FX - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	50	55
Maximum | Measurement Input, FX - FX correlation [Member] | Derivative Financial Instruments | Foreign exchange contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	65	63
Maximum | Measurement Input, FX - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	65	63
Maximum | Measurement Input, Equity - IR correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	25	25
Maximum | Measurement Input, Equity - IR correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	25	25
Maximum | Measurement Input, Equity - FX correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	100	88
Maximum | Measurement Input, Equity volatility [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	157	36
Maximum | Measurement Input, Equity volatility [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	157	49
Maximum | Measurement Input, Credit correlation [Member] | Derivative Financial Instruments | Credit-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	100	100
Maximum | Measurement Input, Credit correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	100	100
Maximum | Measurement Input, Equity correlation [Member] | Derivative Financial Instruments | Equity-related contracts | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivatives financial instruments	[3]	100	100
Maximum | Measurement Input, Equity correlation [Member] | Long-term debt | Internal Valuation Model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt	[3]	100	100
Weighted Average | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	7	8
Weighted Average | Measurement Input, Prepayment Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	21	22
Weighted Average | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	0	0
Weighted Average | Measurement Input, Default Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	2	2
Weighted Average | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	100	100
Weighted Average | Measurement Input Recovery Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	67	69
Weighted Average | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	52	51
Weighted Average | Measurement Input, Discount Rate [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	256	134
Weighted Average | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	22	24
Weighted Average | Measurement Input Discount Rate1 [Member] | Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flows Valuation Technique [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trading securities	[5]	58	295
[1]	These inputs are mainly used for determining the fair values of securitization products such as CDO, CLO and ABS, other than RMBS and CMBS.
[2]	This input represents the counterparty default rate derived from the MHFG Group’s own internal credit analyses.
[3]	Internal valuation model includes discounted cash flow models and the Black-Scholes option pricing model.
[4]	This input is mainly used for determining the fair values of Japanese corporate bonds and foreign corporate bonds.
[5]	Weighted averages are calculated by weighting each input by the relative fair value of the respective financial instruments.

Fair Value (Summary of Assets_3

Fair Value (Summary of Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019
Assets:
Equity securities (without readily determinable fair values)	¥ 419,775	¥ 212,270
Fair Value, Measurements, Nonrecurring
Assets:
Loans	90,000	125,000
Loans held-for-sale	26,000	3,000
Equity securities (without readily determinable fair values)	2,000	1,000
Other investments		98,000
Premises and equipment-net	1,000	9,000
Total assets measured at fair value	119,000	236,000
Fair Value, Measurements, Nonrecurring | Aggregate cost
Assets:
Loans	136,000	177,000
Loans held-for-sale	26,000	3,000
Equity securities (without readily determinable fair values)	2,000	1,000
Other investments		104,000
Premises and equipment-net	12,000	34,000
Intangible assets		1,000
Other assets	3,000
Good will	2,000
Total assets measured at fair value	181,000	320,000
Fair Value, Measurements, Nonrecurring | Level 1
Assets:
Other investments		98,000
Total assets measured at fair value		98,000
Fair Value, Measurements, Nonrecurring | Level 2
Assets:
Loans		41,000
Loans held-for-sale	20,000	3,000
Premises and equipment-net	1,000	4,000
Total assets measured at fair value	21,000	48,000
Fair Value, Measurements, Nonrecurring | Level 3
Assets:
Loans	90,000	84,000
Loans held-for-sale	6,000
Equity securities (without readily determinable fair values)	2,000	1,000
Premises and equipment-net		5,000
Total assets measured at fair value	¥ 98,000	¥ 90,000

Fair Value (Carrying Amounts an

Fair Value (Carrying Amounts and Fair Values of Certain Financial Instruments, Excluding Financial Instruments Carried at Fair Value on a Recurring Basis and Those outside Scope of ASC 825) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2020	Mar. 31, 2019
Financial liabilities:
Long-term debt		¥ 2,537,082	¥ 2,433,294
Carrying amount
Financial assets:
Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		63,755,000	62,012,000
Investments		862,000	1,604,000
Loans, net of allowance for loan losses	[1]	86,914,000	82,382,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		51,954,000	44,918,000
Interest-bearing deposits		114,653,000	112,658,000
Due to trust accounts		250,000	312,000
Other short-term borrowings		4,914,000	1,995,000
Long-term debt		7,821,000	9,096,000
Estimated fair value
Financial assets:
Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		63,755,000	62,012,000
Investments		875,000	1,609,000
Loans, net of allowance for loan losses	[1]	88,124,000	83,490,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		51,954,000	44,918,000
Interest-bearing deposits		114,659,000	112,655,000
Due to trust accounts		250,000	312,000
Other short-term borrowings		4,914,000	1,995,000
Long-term debt		7,708,000	9,178,000
Estimated fair value | Level 1
Financial assets:
Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		1,318,000	873,000
Investments		493,000	1,140,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		29,812,000	24,983,000
Interest-bearing deposits		58,935,000	55,542,000
Estimated fair value | Level 2
Financial assets:
Cash and due from banks, interest-bearing deposits in other banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		62,437,000	61,139,000
Investments		382,000	469,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		22,142,000	19,935,000
Interest-bearing deposits		55,724,000	57,113,000
Due to trust accounts		250,000	312,000
Other short-term borrowings		4,914,000	1,995,000
Long-term debt		6,813,000	8,336,000
Estimated fair value | Level 3
Financial assets:
Loans, net of allowance for loan losses	[1]	88,124,000	83,490,000
Financial liabilities:
Long-term debt		¥ 895,000	¥ 842,000
[1]	Loans, net of allowance for loan losses include items measured at fair value on a nonrecurring basis.

Offsetting of Financial Asset_3

Offsetting of Financial Assets and Financial Liabilities (Information of Offsetting of Financial Assets and Financial Liabilities) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Offsetting Financial Assets And Financial Liabilities [Line Items]
Derivative assets, Gross amounts recognized	¥ 9,819	¥ 7,403
Derivative assets, Gross amounts offset on the balance sheet	0	0
Derivative assets, Net amounts presented on the balance sheet	9,819	7,403
Derivative assets, Amounts not offset on the balance sheet, Financial instruments	(7,723)	(5,903)
Derivative assets, Amounts not offset on the balance sheet, Cash collateral	(629)	(528)
Derivative assets, Net amounts	1,467	972
Receivables under resale agreements, Gross amounts recognized	17,347	12,589
Receivables under resale agreements, Gross amounts offset on the balance sheet	0	0
Receivables under resale agreements, Net amounts presented on the balance sheet	17,347	12,589
Receivables under resale agreements, Amounts not offset on the balance sheet, Financial instruments	(17,197)	(12,579)
Receivables under resale agreements, Amounts not offset on the balance sheet, Cash collateral	0	0
Receivables under resale agreements, Net amounts	150	10
Receivables under securities borrowing transactions, Gross amounts recognized	1,753	1,921
Receivables under securities borrowing transactions, Gross amounts offset on the balance sheet	0	0
Receivables under securities borrowing transactions, Net amounts presented on the balance sheet	1,753	1,921
Receivables under securities borrowing transactions, Amounts not offset on the balance sheet, Financial instruments	(1,709)	(1,894)
Receivables under securities borrowing transactions, Amounts not offset on the balance sheet, Cash collateral	0	0
Receivables under securities borrowing transactions, Net amounts	44	27
Financial assets, Gross amounts recognized, Total	28,919	21,913
Financial assets, Gross amounts offset on the balance sheet, Total	0	0
Financial assets, Net amounts presented on the balance sheet, Total	28,919	21,913
Financial assets, Amounts not offset on the balance sheet, Financial instruments, Total	(26,629)	(20,376)
Financial assets, Amounts not offset on the balance sheet, Cash collateral, Total	(629)	(528)
Financial assets, Net amounts, Total	1,661	1,009
Derivative liabilities, Gross amounts recognized	9,220	6,978
Derivative liabilities, Gross amounts offset on the balance sheet	0	0
Derivative liabilities, Net amounts presented on the balance sheet	9,220	6,978
Derivative liabilities, Amounts not offset on the balance sheet, Financial instruments	(7,519)	(5,766)
Derivative liabilities, Amounts not offset on the balance sheet, Cash collateral	(1,215)	(769)
Derivative liabilities, Net amounts	486	443
Payables under repurchase agreements, Gross amounts recognized	17,542	14,312
Payables under repurchase agreements, Gross amounts offset on the balance sheet	0	0
Payables under repurchase agreements, Net amounts presented on the balance sheet	17,542	14,312
Payables under repurchase agreements, Amounts not offset on the balance sheet, Financial instruments	(17,191)	(14,309)
Payables under repurchase agreements, Amounts not offset on the balance sheet, Cash collateral	0	0
Payables under repurchase agreements, Net amounts	351	3
Payables under securities lending transactions, Gross amounts recognized	626	932
Payables under securities lending transactions, Gross amounts offset on the balance sheet	0	0
Payables under securities lending transactions, Net amounts presented on the balance sheet	626	932
Payables under securities lending transactions, Amounts not offset on the balance sheet, Financial instruments	(623)	(931)
Payables under securities lending transactions, Amounts not offset on the balance sheet, Cash collateral	0	0
Payables under securities lending transactions, Net amounts	3	1
Financial liabilities, Gross amounts recognized, Total	27,388	22,222
Financial liabilities, Gross amounts offset on the balance sheet, Total	0	0
Financial liabilities, Net amounts presented on the balance sheet, Total	27,388	22,222
Financial liabilities, Amounts not offset on the balance sheet, Financial instruments, Total	(25,333)	(21,006)
Financial liabilities, Amounts not offset on the balance sheet, Cash collateral, Total	(1,215)	(769)
Financial liabilities, Net amounts, Total	¥ 840	¥ 447

Repurchase Agreements and Sec_3

Repurchase Agreements and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Amounts of Liabilities by Remaining Contractual Maturity) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2020	Mar. 31, 2019
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	[1]	¥ 17,971	¥ 14,640
Securities lending transactions	[1]	1,424	1,798
Total		19,395	16,438
Overnight and continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		6,357	2,596
Securities lending transactions		877	1,012
Total		7,234	3,608
Up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		5,467	8,537
Securities lending transactions		231	473
Total		5,698	9,010
31 to 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		4,867	2,403
Total		4,867	2,403
Greater than 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		1,280	1,104
Securities lending transactions		316	313
Total		¥ 1,596	¥ 1,417
[1]	Amounts exceeded the gross amounts recognized in Note 28 “Offsetting of financial assets and financial liabilities” by ¥1,194 billion and ¥1,227 billion, at March 31, 2019 and 2020, respectively, which excluded the amounts relating to master netting agreements or similar agreements where the MHFG Group did not have the legal right of set-off or where uncertainty exists as to the enforceability.

Repurchase Agreements and Sec_4

Repurchase Agreements and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Amounts of Liabilities by Class of Underlying Collateral) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2020	Mar. 31, 2019
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	[1]	¥ 17,971	¥ 14,640
Securities lending transactions	[1]	1,424	1,798
Japanese government bonds and Japanese local government bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		1,790	2,118
Securities lending transactions		269	430
Foreign government bonds and foreign agency mortgage-backed securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		15,218	11,613
Securities lending transactions		359	396
Commercial Paper and Corporate Bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		273	223
Securities lending transactions		50	52
Equity Securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		542	492
Securities lending transactions		730	902
Other securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		148	194
Securities lending transactions		¥ 16	¥ 18
[1]	Amounts exceeded the gross amounts recognized in Note 28 “Offsetting of financial assets and financial liabilities” by ¥1,194 billion and ¥1,227 billion, at March 31, 2019 and 2020, respectively, which excluded the amounts relating to master netting agreements or similar agreements where the MHFG Group did not have the legal right of set-off or where uncertainty exists as to the enforceability.

Repurchase Agreements and Sec_5

Repurchase Agreements and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Amounts of Liabilities by Class of Underlying Collateral) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2020	Mar. 31, 2019
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Amounts exceeded the gross amounts recognized in offsetting of financial assets and financial liabilities	¥ 1,227	¥ 1,194

Related Party Transactions - Su

Related Party Transactions - Summary of financial information of groups equity method investees (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Related Party Transaction [Line Items]
Loans	¥ 87,528,088	¥ 82,799,943
Total assets	211,218,760	197,611,195	¥ 204,255,600
Total liabilities	202,043,136	188,109,702
Total equity	9,175,624	9,501,493	9,503,700
Noncontrolling interests	663,259	774,974
Total interest and dividend income	2,151,172	2,207,443	1,761,886
Total interest expense	1,271,381	1,313,476	889,936
Provision (credit) for loan losses	156,200	32,459	(126,362)
Net interest income after provision (credit) for loan losses	723,591	861,508	998,312
Income before income tax expense	153,490	85,060	839,298
Net income	106,315	75,725	601,694
Equity Method Investee
Related Party Transaction [Line Items]
Loans	7,268,000	7,954,000
Total assets	27,036,000	28,674,000
Deposits	8,665,000	10,167,000
Total liabilities	25,014,000	26,387,000
Total equity	2,022,000	2,287,000
Noncontrolling interests	11,000	615,000
Total interest and dividend income	586,000	503,000	458,000
Total interest expense	198,000	165,000	153,000
Provision (credit) for loan losses	81,000	84,000	66,000
Net interest income after provision (credit) for loan losses	307,000	254,000	239,000
Income before income tax expense	196,000	229,000	149,000
Net income	¥ 150,000	¥ 201,000	¥ 132,000

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) ¥ in Billions	12 Months Ended
	Mar. 31, 2020JPY (¥)Loans	Mar. 31, 2019JPY (¥)Loans
Related Party Transaction [Line Items]
Number of loans impaired | Loans	0	0
Related party loan | ¥	¥ 497	¥ 473

Business Segment Information -

Business Segment Information - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2020Segment
Segment Reporting Information [Line Items]
Number of operating segments	5

Business Segment Information (R

Business Segment Information (Reportable Segment Information Derived from Internal Management Reporting Systems, on Basis of Japanese GAAP) (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2018	[2]
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	¥ 2,072.8	[1]	¥ 1,827.7	[2]	¥ 1,995.6
General and administrative expenses	1,411.5	[3]	1,440.6	[2]	1,444.2
Equity in earnings (losses) of equity method investees-net	30.4		51.2	[2]	21.5
Amortization of goodwill and others	13.2		13.6	[2]	13.9
Others	(5.9)		(16.3)	[2]	(21)
Net business profits (losses) + Net gains (losses) related to ETFs and others	672.6		408.4	[4]	538
Fixed assets	1,739.8		1,657.2	[2]
Operating Segments | Retail And Business Banking Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	673.6	[1]	705.9	[2]	725.7
General and administrative expenses	668.5	[3]	713.5	[2]	724.3
Equity in earnings (losses) of equity method investees-net	11.8		18.1	[2]	12.7
Amortization of goodwill and others	0.4		0.4	[2]	0.4
Others
Net business profits (losses) + Net gains (losses) related to ETFs and others	16.5		10.1	[4]	13.7
Fixed assets	503.7		499.3	[2]
Operating Segments | Corporate And Institutional Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	462.4	[1]	473.4	[2]	431
General and administrative expenses	215.1	[3]	205.7	[2]	208.4
Equity in earnings (losses) of equity method investees-net	2		0.9	[2]	1
Amortization of goodwill and others	0.4		0.4	[2]	0.4
Others
Net business profits (losses) + Net gains (losses) related to ETFs and others	248.9		268.2	[4]	223.2
Fixed assets	204.1		225.8	[2]
Operating Segments | Global Corporate Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	417.8	[1]	400.3	[2]	327.3
General and administrative expenses	249	[3]	237.9	[2]	239.6
Equity in earnings (losses) of equity method investees-net	10.3		7.2	[2]	2.3
Amortization of goodwill and others	0.4		0.4	[2]	0.4
Others
Net business profits (losses) + Net gains (losses) related to ETFs and others	178.7		169.2	[4]	89.6
Fixed assets	173		176.9	[2]
Operating Segments | Global Markets Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	410.1	[1]	192.4	[2]	387.2
General and administrative expenses	208.9	[3]	207.5	[2]	204.7
Equity in earnings (losses) of equity method investees-net
Amortization of goodwill and others	2.3		2.3	[2]	2.3
Others
Net business profits (losses) + Net gains (losses) related to ETFs and others	198.9		(17.4)	[4]	180.2
Fixed assets	91.5		92.6	[2]
Operating Segments | Asset Management Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	48.4	[1]	49.6	[2]	50
General and administrative expenses	29	[3]	27.3	[2]	27.6
Equity in earnings (losses) of equity method investees-net	1.3		1.3	[2]	2.9
Amortization of goodwill and others	7.8		8	[2]	8
Others
Net business profits (losses) + Net gains (losses) related to ETFs and others	12.9		15.6	[4]	17.3
Fixed assets	0.1		0.1	[2]
Others
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits + Net gains (losses) related to ETFs and others	60.5	[5]	6.1	[2]	74.4
General and administrative expenses	41	[5]	48.7	[2]	39.6
Equity in earnings (losses) of equity method investees-net	5	[5]	23.7	[2]	2.6
Amortization of goodwill and others	1.9	[5]	2.1	[2]	2.4
Others	(5.9)	[5]	(16.3)	[2]	(21)
Net business profits (losses) + Net gains (losses) related to ETFs and others	16.7	[5]	(37.3)	[4]	¥ 14
Fixed assets	¥ 767.4	[5]	¥ 662.5	[2]
[1]	“Gross profits + Net gains (losses) related to ETFs and others” is reported instead of sales reported by general corporations. Gross profits is defined as the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income. Net gains (losses) related to ETFs and others consist of net gains (losses) on ETFs held by MHBK and MHTB on their non-consolidated basis and net gains (losses) on operating investment securities of MHSC on its consolidated basis. For the fiscal years ended March 31, 2018, 2019 and 2020, net gains (losses) related to ETFs and others amounted to ¥80.2 billion, ¥15.0 billion and ¥10.6 billion, respectively, of which ¥70.1 billion, ¥7.3 billion and ¥7.3 billion are included in “Global Markets Company,” respectively.
[2]	Beginning on April 1, 2018, new allocation methods for income and expense transactions between each segment and “Others” have been applied. In connection with the use of the new allocation methods, the presentation of “Net business profits” has changed to “Net business profits (losses) + Net gains (losses) related to ETFs and others.” Before the change, “Net gains (losses) related to ETFs and others” were included in “Gross profits” of each segment and eliminated in “Others.” In addition, “Amortization of goodwill and others” has been presented as a new item. Figures for the fiscal year ended March 31, 2018 have been restated for the new allocation methods. These changes more appropriately reflect the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates.
[3]	“General and administrative expenses” excludes non-allocated gains (losses), net.
[4]	Net business profits (losses) is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (as defined above) less general and administrative expenses plus equity in earnings (losses) of equity method investees—net and others. Measurement of net business profits (losses) is required for regulatory reporting to the Financial Services Agency of Japan.
[5]	“Others” includes the following items: • profits and expenses pertaining to consolidated subsidiaries that are not subject to allocation; • consolidating adjustments, including eliminating internal transaction between each segment; • equity in earnings (losses) of equity method investees-net that are not subject to allocation; and • profits and losses pertaining to derivative transactions that reflect the counterparty risk of the individual parties and other factors in determining fair market value.

Business Segment Information _2

Business Segment Information (Reportable Segment Information Derived from Internal Management Reporting Systems, on Basis of Japanese GAAP) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2020		Mar. 31, 2019		Mar. 31, 2018
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits and net gains (losses) related to ETFs and others	¥ 2,072.8	[1]	¥ 1,827.7	[2]	¥ 1,995.6	[2]
Exchange Traded Funds
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits and net gains (losses) related to ETFs and others	10.6		15		80.2
Global Markets Company | Exchange Traded Funds
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits and net gains (losses) related to ETFs and others	¥ 7.3		¥ 7.3		¥ 70.1
[1]	“Gross profits + Net gains (losses) related to ETFs and others” is reported instead of sales reported by general corporations. Gross profits is defined as the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income. Net gains (losses) related to ETFs and others consist of net gains (losses) on ETFs held by MHBK and MHTB on their non-consolidated basis and net gains (losses) on operating investment securities of MHSC on its consolidated basis. For the fiscal years ended March 31, 2018, 2019 and 2020, net gains (losses) related to ETFs and others amounted to ¥80.2 billion, ¥15.0 billion and ¥10.6 billion, respectively, of which ¥70.1 billion, ¥7.3 billion and ¥7.3 billion are included in “Global Markets Company,” respectively.
[2]	Beginning on April 1, 2018, new allocation methods for income and expense transactions between each segment and “Others” have been applied. In connection with the use of the new allocation methods, the presentation of “Net business profits” has changed to “Net business profits (losses) + Net gains (losses) related to ETFs and others.” Before the change, “Net gains (losses) related to ETFs and others” were included in “Gross profits” of each segment and eliminated in “Others.” In addition, “Amortization of goodwill and others” has been presented as a new item. Figures for the fiscal year ended March 31, 2018 have been restated for the new allocation methods. These changes more appropriately reflect the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates.

Business Segment Information _3

Business Segment Information (Reconciliation of Total Net Business Profits under Internal Management Reporting Systems to Income Before Income Tax Expense on Consolidated Statements of Income) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net business profits (losses) + Net gains (losses) related to ETFs and others	¥ 672,600	¥ 408,400	¥ 538,000
Adjustment to reconcile management reporting to Japanese GAAP:
General and administrative expenses: non-allocated gains (losses), net	46,300	23,300	(30,900)
Expenses related to portfolio problems (including reversal of (provision for) general reserve for losses on loans)	(183,300)	(30,700)	(17,000)
Gains on reversal of reserves for possible losses on loans, and others	11,600	11,200	173,300
Net gains (losses) related to stocks—Net gains (losses) related to ETFs and others	126,600	259,900	191,900
Net extraordinary gains(losses)	(19,200)	(497,900)	17,500
Others	(35,900)	(57,900)	(72,800)
Income before income tax expense under Japanese GAAP	618,700	116,300	800,000
Adjustment to reconcile Japanese GAAP to U.S. GAAP:
Derivative financial instruments and hedging activities	111,200	45,300	(110,200)
Investments	(480,900)	(273,300)	98,100
Loans	(3,000)	(11,900)	(2,400)
Allowances for loan losses and off-balance-sheet instruments	700	(5,800)	6,800
Premises and equipment	(96,100)	303,600	35,400
Land revaluation	2,100	10,200	3,400
Business combinations	6,000	(12,800)	15,600
Pension liabilities	(56,700)	(32,200)	(4,400)
Consolidation of variable interest entities	39,300	(39,000)	2,700
Foreign currency translation	17,300	1,700	12,100
Others	(5,100)	(17,000)	(17,800)
Income before income tax expense	¥ 153,490	¥ 85,060	¥ 839,298

Business Segment Information _4

Business Segment Information (Reconciliation of Assets from Segment to Consolidated) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Schedule Of Assets By Segment [Line Items]
Fixed assets		¥ 1,739.8	¥ 1,657.2	[1]
U.S. GAAP adjustments	[2]	887.2	413.1
Premises and equipment—net, Goodwill, Intangible assets, and ROU assets related to operating leases included in Other assets		¥ 2,627	¥ 2,070.3
[1]	Beginning on April 1, 2018, new allocation methods for income and expense transactions between each segment and “Others” have been applied. In connection with the use of the new allocation methods, the presentation of “Net business profits” has changed to “Net business profits (losses) + Net gains (losses) related to ETFs and others.” Before the change, “Net gains (losses) related to ETFs and others” were included in “Gross profits” of each segment and eliminated in “Others.” In addition, “Amortization of goodwill and others” has been presented as a new item. Figures for the fiscal year ended March 31, 2018 have been restated for the new allocation methods. These changes more appropriately reflect the performance of each of the operating segments in accordance with internal managerial accounting rules and practices. Income and expenses of foreign branches of MHBK and foreign subsidiaries with functional currencies other than Japanese Yen have been translated for purposes of segment reporting using the budgeted foreign currency rates. Prior period comparative amounts for such foreign currency income and expenses have been translated using current period budgeted foreign currency rates.
[2]	The U.S. GAAP adjustments are primarily comprised of GAAP differences mainly from ROU assets related to operating leases not recognized under Japanese GAAP; internally developed software, which was impaired under Japanese GAAP; land, which was revalued under Japanese GAAP; and the consolidation of certain variable interest entities, which are not consolidated under Japanese GAAP. ROU assets are recognized on balance sheets in connection with the adoption of ASU No.2016-02 on April 1, 2019.

Foreign Activities (Consolidate

Foreign Activities (Consolidated Income Statement and Total Assets Information by Major Geographic Area) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total revenue	[1]	¥ 3,458,900	¥ 3,429,800	¥ 3,366,500
Total expenses	[2]	3,305,400	3,344,700	2,527,200
Income before income tax expense		153,490	85,060	839,298
Net income		106,315	75,725	601,694
Total assets at end of fiscal year		211,218,760	197,611,195	204,255,600
Japan
Segment Reporting Information [Line Items]
Total revenue	[1]	1,681,000	1,705,500	2,002,400
Total expenses	[2]	2,008,900	2,082,600	1,582,500
Income before income tax expense		(327,900)	(377,100)	419,900
Net income		(312,800)	(331,400)	231,300
Total assets at end of fiscal year		137,470,400	133,443,500	142,587,800
United States of America
Segment Reporting Information [Line Items]
Total revenue	[1]	801,500	792,100	654,900
Total expenses	[2]	679,200	696,500	478,800
Income before income tax expense		122,300	95,600	176,100
Net income		100,400	85,300	152,700
Total assets at end of fiscal year		34,650,400	25,913,500	28,135,900
Others
Segment Reporting Information [Line Items]
Total revenue	[1]	95,100	66,000	64,000
Total expenses	[2]	41,500	46,100	38,500
Income before income tax expense		53,600	19,900	25,500
Net income		51,500	17,000	23,700
Total assets at end of fiscal year		4,137,300	4,824,700	4,380,400
Europe
Segment Reporting Information [Line Items]
Total revenue	[1]	270,400	249,700	197,400
Total expenses	[2]	239,100	203,200	172,600
Income before income tax expense		31,300	46,500	24,800
Net income		23,600	34,600	21,300
Total assets at end of fiscal year		15,487,000	15,322,500	11,677,800
Asia/Oceania excluding Japan, and others
Segment Reporting Information [Line Items]
Total revenue	[1]	610,900	616,500	447,800
Total expenses	[2]	336,700	316,300	254,800
Income before income tax expense		274,200	300,200	193,000
Net income		243,600	270,200	172,700
Total assets at end of fiscal year		¥ 19,473,700	¥ 18,107,000	¥ 17,473,700
[1]	Total revenue is comprised of Interest and dividend income and Noninterest income.
[2]	Total expenses are comprised of Interest expense, Provision (credit) for loan losses and Noninterest expenses.

Mizuho Financial Group, Inc.,_3

Mizuho Financial Group, Inc., Parent Company (Condensed Balance Sheets) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Assets:
Cash and due from banking subsidiaries	¥ 2,325,139	¥ 1,404,008
Interest-bearing deposits in banking subsidiaries	39,625,975	44,268,731
Other	5,965,879	5,276,004
Total assets	211,218,760	197,611,195	¥ 204,255,600
Liabilities and shareholders' equity:
Long-term debt	10,346,152	11,529,400
Other liabilities	6,998,395	5,932,706
Shareholders' equity	8,512,365	8,726,519
Total liabilities and equity	211,218,760	197,611,195
Parent Company
Assets:
Cash and due from banking subsidiaries	43,016	99,209
Interest-bearing deposits in banking subsidiaries	218	1,158
Long-term loans receivable from a banking subsidiary	6,539,819	5,110,248
Other	471,225	351,951
Total assets	16,298,634	14,879,953
Liabilities and shareholders' equity:
Short-term borrowings from a banking subsidiary	860,000	945,505
Long-term debt	6,555,053	5,145,286
Other liabilities	371,216	62,643
Shareholders' equity	8,512,365	8,726,519
Total liabilities and equity	16,298,634	14,879,953
Parent Company | Banking Subsidiaries
Assets:
Investments in subsidiaries and affiliated companies	8,104,662	7,905,018
Parent Company | Non Banking Subsidiaries And Affiliated Companies
Assets:
Investments in subsidiaries and affiliated companies	¥ 1,139,694	¥ 1,412,369

Mizuho Financial Group, Inc.,_4

Mizuho Financial Group, Inc., Parent Company (Condensed Statements of Income) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Income:
Gains on disposal of premises and equipment	[1]	¥ 2,583	¥ 5,145	¥ 8,225
Total	[2]	3,458,900	3,429,800	3,366,500
Expenses:
Interest expense		1,271,381	1,313,476	889,936
Equity in undistributed net income (loss) of subsidiaries	[1]	34,012	29,172	24,342
Income tax expense (benefit)		47,175	9,335	237,604
Net income attributable to MHFG shareholders		150,195	84,471	577,608
Parent Company
Income:
Management fees from subsidiaries		38,004	39,292	47,945
Interest income on loans and discounts		123,354	106,920	68,869
Gains on disposal of premises and equipment		10,866
Other income		7,088	9,575	52,672
Total		215,986	446,903	425,530
Expenses:
Operating expenses		38,951	40,680	38,661
Interest expense		126,516	110,861	74,227
Other expense		25,313	59,049	28,123
Total		190,780	210,590	141,011
Equity in undistributed net income (loss) of subsidiaries		130,930	(173,142)	309,210
Income before income tax expense		156,136	63,171	593,729
Income tax expense (benefit)		5,941	(21,300)	16,121
Net income attributable to MHFG shareholders		150,195	84,471	577,608
Parent Company | Banking Subsidiary
Income:
Banking subsidiaries		23,824	267,724	227,057
Parent Company | Non Banking Subsidiaries And Affiliated Companies
Income:
Banking subsidiaries		¥ 12,850	¥ 23,392	¥ 28,987
[1]	These amounts are revenues from contracts that do not meet the scope of ASC 606.
[2]	Total revenue is comprised of Interest and dividend income and Noninterest income.

Mizuho Financial Group, Inc.,_5

Mizuho Financial Group, Inc., parent company (Condensed statements of cash flows) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income		¥ 150,195	¥ 84,471	¥ 577,608
Net cash provided by operating activities		(4,041,072)	661,019	(161,076)
Cash flows from investing activities:
Proceeds from sales of Equity securities	[1]	3,123,341	3,973,437
Net change in loans		(7,512,885)	(3,852,757)	(1,971,210)
Purchases of premises and equipment		(243,022)	(157,714)	(292,201)
Net cash provided by (used in) investing activities		(11,807,589)	(6,773,772)	(3,624,755)
Cash flows from financing activities:
Net change in short-term borrowings		2,936,677	270,560	257,774
Proceeds from issuance of long-term debt		2,303,803	1,659,412	1,956,007
Repayment of long-term debt		(3,273,353)	(3,241,799)	(3,310,804)
Proceeds from issuance of common stock			3	3
Purchases of treasury stock		(1,441)	(2,124)	(1,611)
Dividends paid		(190,386)	(190,413)	(190,382)
Net cash provided by financing activities		12,356,954	3,408,385	4,652,627
Effect of exchange rate changes on cash and cash equivalents		(229,918)	206,186	(282,846)
Cash and cash equivalents at beginning of period		45,672,739	48,170,921	47,586,971
Cash and cash equivalents at end of period		41,951,114	45,672,739	48,170,921
Parent Company
Cash flows from operating activities:
Net income		150,195	84,471	577,608
Adjustments and other		(92,059)	197,193	(302,109)
Net cash provided by operating activities		58,136	281,664	275,499
Cash flows from investing activities:
Proceeds from sales of Equity securities			139,719
Net change in loans		(1,496,047)	(1,075,059)	(1,344,323)
Purchases of premises and equipment		(43,406)	(11,640)	(6,649)
Proceeds from sales of premises and equipment		209,657
Net change in other investing activities		(5,150)	(1,310)	(4,114)
Net cash provided by (used in) investing activities		(1,334,946)	(948,290)	(1,355,086)
Cash flows from financing activities:
Net change in short-term borrowings		(85,505)	(140,000)	(70,000)
Proceeds from issuance of long-term debt		1,531,047	1,075,059	1,344,323
Repayment of long-term debt		(35,000)
Proceeds from issuance of common stock			3	3
Purchases of treasury stock		(1,441)	(2,124)	(1,611)
Dividends paid		(190,386)	(190,413)	(190,382)
Net change in other financing activities		962	437	555
Net cash provided by financing activities		1,219,677	742,962	1,082,888
Effect of exchange rate changes on cash and cash equivalents			540
Net increase (decrease) in cash and cash equivalents		(57,133)	76,876	3,301
Cash and cash equivalents at beginning of period		100,367	23,491	20,190
Cash and cash equivalents at end of period		¥ 43,234	¥ 100,367	¥ 23,491
[1]	Proceeds from sales of Equity securities as well as Purchases of Equity securities include cash activity related to Other investments for the fiscal years ended March 31, 2019 and 2020, the amounts of which are not significant.

Subsequent events - Additional

Subsequent events - Additional Information (Detail)	Jun. 25, 2020
Subsequent Events [Abstract]
Stockholders equity stock consolidation	1-for-10 share