Mizuho Financial (MFG) 20-F 7 Jul 17 2016 FY Annual report (foreign) Financial data

Document and Entity Information

Document and Entity Information	12 Months Ended
	Mar. 31, 2017shares
Document Type	20-F
Amendment Flag	false
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	MFG
Entity Registrant Name	MIZUHO FINANCIAL GROUP INC
Entity Central Index Key	1,335,730
Current Fiscal Year End Date	--03-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	25,386,307,945

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Assets:
Cash and due from banks	¥ 1,592,191	¥ 1,322,597
Interest-bearing deposits in other banks	45,994,780	35,327,408
Call loans and funds sold	1,037,986	893,545
Receivables under resale agreements (Note 29)	8,967,712	7,805,643
Receivables under securities borrowing transactions (Note 29)	3,350,052	3,407,391
Trading account assets	24,998,493	30,020,743
Investments (Notes 4, 9 and 28):
Available-for-sale securities (including assets pledged that secured parties are permitted to sell or repledge of ¥513,054 million in 2016 and ¥442,775 million in 2017)	20,557,118	25,452,525
Held-to-maturity securities (including assets pledged that secured parties are permitted to sell or repledge of ¥1,238,965 million in 2016 and ¥1,050,714 million in 2017)	3,817,360	4,818,961
Other investments	595,069	613,446
Loans (Notes 5, 6, 9 and 28)	82,283,906	77,555,369
Allowance for loan losses	(479,673)	(451,247)
Loans, net of allowance	81,804,233	77,104,122
Premises and equipment-net (Note 7)	2,041,273	1,837,990
Due from customers on acceptances	184,171	109,567
Accrued income	270,694	274,226
Goodwill (Note 8)	95,176	19,097
Intangible assets (Note 8)	94,147	48,651
Deferred tax assets (Note 20)	63,520	57,349
Other	4,992,329	4,696,890
Total	200,456,304	193,810,151
Liabilities and equity:
Noninterest-bearing deposits	19,063,774	16,108,032
Interest-bearing deposits	87,358,504	79,596,483
Noninterest-bearing deposits	1,996,450	1,601,417
Interest-bearing deposits	22,766,225	20,631,790
Due to trust accounts (Note 11)	4,123,088	4,467,305
Call money and funds purchased	1,255,172	2,521,009
Payables under repurchase agreements (Notes 29 and 30)	17,969,941	16,833,263
Payables under securities lending transactions (Notes 29 and 30)	1,919,249	2,844,653
Other short-term borrowings	1,476,612	2,080,039
Trading account liabilities	13,591,740	17,111,142
Bank acceptances outstanding	184,171	109,567
Income taxes payable	73,598	96,710
Deferred tax liabilities (Note 20)	140,475	201,859
Accrued expenses	209,309	181,441
Long-term debt	14,529,414	14,765,527
Other	5,026,525	6,476,723
Total	191,684,247	185,626,960
Commitments and contingencies (Note 24)
MHFG shareholders' equity:
Preferred stock (Note 14)		98,924
Common stock (Note 15)-no par value, authorized 48,000,000,000 shares in 2016 and 2017, and issued 25,030,525,657 shares in 2016, and 25,386,307,945 shares in 2017	5,826,149	5,703,144
Retained earnings	918,894	746,785
Accumulated other comprehensive income, net of tax (Note 17)	1,521,163	1,469,308
Less: Treasury stock, at cost-Common stock 10,929,211 shares in 2016, and 19,992,754 shares in 2017	(4,849)	(3,610)
Total MHFG shareholders' equity	8,261,357	8,014,551
Noncontrolling interests	510,700	168,640
Total equity	8,772,057	8,183,191
Total	200,456,304	193,810,151
Consolidated VIEs
Assets:
Cash and due from banks	96,077	51,304
Interest-bearing deposits in other banks	81,807	85,976
Trading account assets	2,099,890	1,639,050
Investments (Notes 4, 9 and 28):
Investments	46,180	40,732
Loans, net of allowance	2,149,321	2,255,409
Other	772,290	620,008
Total	5,245,565	4,692,479
Liabilities and equity:
Other short-term borrowings	60,575	292,614
Trading account liabilities	7,723
Long-term debt	431,190	411,679
Other	1,147,895	967,141
Total	¥ 1,647,383	¥ 1,671,434

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Trading account assets, assets pledged that secured parties are permitted to sell or repledge	¥ 5,861,942	¥ 7,020,645
Available-for-sale securities, assets pledged that secured parties are permitted to sell or repledge	442,775	513,054
Held-to-maturity securities, assets pledged that secured parties are permitted to sell or repledge	1,050,714	1,238,965
Long-term debt, liabilities accounted for at fair value	¥ 1,496,488	¥ 1,055,626
Common stock, par value	¥ 0	¥ 0
Common stock, authorized	48,000,000,000	48,000,000,000
Common stock, issued	25,386,307,945	25,030,525,657
Treasury stock, shares	19,992,754	10,929,211

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Interest and dividend income:
Loans, including fees		¥ 1,009,094	¥ 1,030,802	¥ 988,236
Investments:
Interest		88,311	110,411	130,626
Dividends		77,343	79,600	74,673
Trading account assets		163,114	151,278	174,458
Call loans and funds sold		5,068	6,983	7,555
Receivables under resale agreements and securities borrowing transactions		91,453	53,007	33,379
Deposits		74,647	68,090	48,732
Total interest and dividend income		1,509,030	1,500,171	1,457,659
Interest expense:
Deposits		264,748	213,601	149,776
Trading account liabilities		21,399	21,031	31,402
Call money and funds purchased		3,173	7,830	7,545
Payables under repurchase agreements and securities lending transactions		120,578	66,579	36,641
Other short-term borrowings		12,175	6,791	7,490
Long-term debt		179,639	179,575	179,128
Total interest expense		601,712	495,407	411,982
Net interest income		907,318	1,004,764	1,045,677
Provision (credit) for loan losses (Notes 5 and 6)		37,668	34,560	(60,223)
Net interest income after provision (credit) for loan losses		869,650	970,204	1,105,900
Noninterest income:
Fee and commission income (Note 26)		746,537	742,953	715,657
Foreign exchange gains (losses)-net (Note 27)	[1]	69,453	113,553	(34,520)
Trading account gains (losses)-net (Note 27)		(42,481)	559,139	689,959
Investment gains (losses)-net (Note 4)		333,270	263,793	271,174
Equity in earnings (losses) of equity method investees-net		26,785	28,969	17,502
Gains on disposal of premises and equipment		5,638	10,223	2,754
Other noninterest income		228,830	165,264	138,689
Total noninterest income		1,368,032	1,883,894	1,801,215
Noninterest expenses:
Salaries and employee benefits (Note 21)		663,166	633,557	605,454
General and administrative expenses		570,897	548,027	530,365
Impairment of goodwill (Note 8)			6,222
Occupancy expenses		194,955	195,898	189,004
Fee and commission expenses		148,483	146,107	134,395
Provision (credit) for losses on off-balance-sheet instruments (Note 24)		19,464	(16,447)	(2,827)
Other noninterest expenses		160,342	144,129	183,071
Total noninterest expenses		1,757,307	1,657,493	1,639,462
Income before income tax expense		480,375	1,196,605	1,267,653
Income tax expense (Note 20)		91,244	346,542	437,420
Net income		389,131	850,063	830,233
Less: Net income (loss) attributable to noncontrolling interests		26,691	(429)	27,185
Net income attributable to MHFG shareholders		¥ 362,440	¥ 850,492	¥ 803,048
Earnings per common share (Note 19):
Basic net income per common share		¥ 14.33	¥ 34.19	¥ 32.75
Diluted net income per common share		¥ 14.28	¥ 33.50	¥ 31.64
[1]	Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments, such as translation gains and losses related to foreign currency-denominated available-for-sale securities for which the fair value option has been elected in accordance with ASC 825.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Net income	¥ 389,131	¥ 850,063	¥ 830,233
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on available-for-sale securities, net of tax (Note 4)	51,957	(338,822)	622,975
Foreign currency translation adjustments, net of tax	(12,322)	(123,221)	136,299
Pension liability adjustments, net of tax (Note 21)	11,922	(111,599)	163,338
Change during year	51,557	(573,642)	922,612
Total comprehensive income	440,688	276,421	1,752,845
Less: Total comprehensive income (loss) attributable to noncontrolling interests	26,724	(2,373)	26,669
Total comprehensive income attributable to MHFG shareholders	¥ 413,964	¥ 278,794	¥ 1,726,176

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - JPY (¥) ¥ in Millions	Total	Preferred stock (Note 14):	Common stock (Note 15):	Retained earnings (Accumulated deficit):	Accumulated other comprehensive income, net of tax (Note 17):	Treasury stock, at cost:	Total MHFG shareholders' equity	Noncontrolling interests:
Balance at beginning of fiscal year at Mar. 31, 2014		¥ 312,651	¥ 5,489,295	¥ (537,479)	¥ 1,117,877	¥ (3,874)		¥ 242,901
Issuance of new shares of common stock due to conversion of preferred stock			99,530
Effect of other increase (decrease) in consolidated subsidiaries								(6,128)
Net income attributable to MHFG shareholders	¥ 803,048			803,048
Purchases of treasury stock						(274)
Conversion to common stock		(99,530)
Change during year	922,612				923,128
Issuance of new shares of common stock due to exercise of stock acquisition rights			864
Dividends paid to noncontrolling interests								(3,936)
Dividends declared	(176,137)			(176,137)
Disposal of treasury stock						532
Gains (losses) on disposal of treasury stock			67
Net income (loss) attributable to noncontrolling interests	(27,185)							27,185
Stock-based compensation related to stock options (Note 22)			640
Net unrealized gains (losses) on available-for-sale securities attributable to noncontrolling interests								(1,360)
Foreign currency translation adjustments attributable to noncontrolling interests								686
Pension liability adjustments attributable to noncontrolling interests								158
Balance at end of fiscal year at Mar. 31, 2015	8,189,844	213,121	5,590,396	89,432	2,041,005	(3,616)	¥ 7,930,338	259,506
Issuance of new shares of common stock due to conversion of preferred stock			114,197
Effect of other increase (decrease) in consolidated subsidiaries								(85,809)
Net income attributable to MHFG shareholders	850,492			850,492
Purchases of treasury stock						(653)
Conversion to common stock		(114,197)
Change during year	(573,642)				(571,697)
Issuance of new shares of common stock due to exercise of stock acquisition rights			772
Dividends paid to noncontrolling interests								(2,683)
Dividends declared	(195,265)			(195,265)
Disposal of treasury stock						659
Gains (losses) on disposal of treasury stock			82
Net income (loss) attributable to noncontrolling interests	429							(429)
Other				2,126
Stock-based compensation related to stock options (Note 22)			(1,058)
Net unrealized gains (losses) on available-for-sale securities attributable to noncontrolling interests								(674)
Foreign currency translation adjustments attributable to noncontrolling interests								(352)
Change in ownership interests in consolidated subsidiaries			(1,245)
Pension liability adjustments attributable to noncontrolling interests								(919)
Balance at end of fiscal year (Previously Reported) at Mar. 31, 2016				746,785	1,469,308			168,640
Balance at end of fiscal year (Restatement Adjustment)				(329)	330			(10,441)
Balance at end of fiscal year at Mar. 31, 2016	8,183,191	98,924	5,703,144	746,456	1,469,638	(3,610)	8,014,551	158,199
Issuance of new shares of common stock due to conversion of preferred stock			98,924
Effect of other increase (decrease) in consolidated subsidiaries								328,692
Net income attributable to MHFG shareholders	362,440			362,440
Purchases of treasury stock						(1,903)
Conversion to common stock		¥ (98,924)
Change during year	51,557				51,525
Issuance of new shares of common stock due to exercise of stock acquisition rights			969
Dividends paid to noncontrolling interests								(2,914)
Dividends declared	(190,002)			(190,002)
Disposal of treasury stock						663
Gains (losses) on disposal of treasury stock			(56)
Net income (loss) attributable to noncontrolling interests	(26,691)							26,691
Stock-based compensation related to stock options (Note 22)			(1,009)
Net unrealized gains (losses) on available-for-sale securities attributable to noncontrolling interests								29
Performance-based stock compensation program			354
Foreign currency translation adjustments attributable to noncontrolling interests								(62)
Change in ownership interests in consolidated subsidiaries			23,824
Pension liability adjustments attributable to noncontrolling interests								65
Cancellation of treasury stock			(1)			1
Balance at end of fiscal year at Mar. 31, 2017	¥ 8,772,057		¥ 5,826,149	¥ 918,894	¥ 1,521,163	¥ (4,849)	¥ 8,261,357	¥ 510,700

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	¥ 389,131	¥ 850,063	¥ 830,233
Less: Net income (loss) attributable to noncontrolling interests	26,691	(429)	27,185
Net income attributable to MHFG shareholders	362,440	850,492	803,048
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	171,202	167,930	166,528
Provision (credit) for loan losses	37,668	34,560	(60,223)
Investment losses (gains)-net	(333,270)	(263,793)	(271,174)
Equity in losses (earnings) of equity method investees-net	(26,785)	(28,969)	(17,502)
Foreign exchange losses (gains)-net	22,812	(225,130)	357,103
Deferred income tax expense (benefit)	(107,432)	123,125	181,990
Net change in trading account assets	4,867,508	(778,204)	(2,121,400)
Net change in trading account liabilities	(3,267,060)	916,958	1,333,577
Net change in loans held for sale	(5,574)	(27,347)	56,549
Net change in accrued income	7,087	(2,441)	(7,531)
Net change in accrued expenses	4,485	(26,425)	87,157
Other-net	(519,773)	(499,046)	697,804
Net cash provided by operating activities	1,213,308	241,710	1,205,926
Cash flows from investing activities:
Proceeds from sales of investments	31,139,716	19,830,288	58,629,117
Proceeds from maturities of investments	8,099,488	8,669,730	6,107,552
Purchases of investments	(34,137,270)	(25,046,188)	(61,507,248)
Proceeds from sales of loans	291,782	197,898	651,339
Net change in loans	(5,606,627)	(1,923,627)	(2,800,196)
Net change in interest-bearing deposits in other banks	(10,688,447)	(7,750,251)	(8,189,150)
Net change in call loans and funds sold, and receivables under resale agreements and securities borrowing transactions	(1,481,661)	385,134	1,813,089
Proceeds from sales of premises and equipment	12,059	47,506	41,521
Purchases of premises and equipment	(430,913)	(388,565)	(419,912)
Cash and due from banks acquired in business combination	301
Net cash used in investing activities	(12,801,572)	(5,978,075)	(5,673,888)
Cash flows from financing activities:
Net change in deposits	14,005,565	5,441,731	9,460,669
Net change in call money and funds purchased, and payables under repurchase agreements and securities lending transactions	(771,368)	(3,900,502)	(5,376,701)
Net change in due to trust accounts	(344,217)	3,226,204	499,065
Net change in other short-term borrowings	(589,512)	571,901	(4,480,378)
Proceeds from issuance of long-term debt	4,496,041	2,723,168	6,537,703
Repayment of long-term debt	(4,734,010)	(2,307,082)	(2,196,492)
Proceeds from noncontrolling interests	3,323	1,354	891
Payments to noncontrolling interests		(86)	(1)
Proceeds from issuance of common stock	6	5	6
Proceeds from sales of treasury stock	1	3	3
Purchases of treasury stock	(1,435)	(13)	(12)
Purchases of treasury stock of subsidiaries	(1,696)
Dividends paid	(190,031)	(195,283)	(176,186)
Dividends paid to noncontrolling interests	(2,914)	(2,683)	(3,936)
Net cash provided by financing activities	11,869,753	5,558,717	4,264,631
Effect of exchange rate changes on cash and due from banks	(11,895)	(28,061)	34,758
Net increase (decrease) in cash and due from banks	269,594	(205,709)	(168,573)
Cash and due from banks at beginning of fiscal year	1,322,597	1,528,306	1,696,879
Cash and due from banks at end of fiscal year	1,592,191	1,322,597	1,528,306
Supplemental disclosure of cash flow information:
Interest paid	582,947	435,584	419,070
Income taxes paid	246,802	269,364	172,022
Noncash investing activities:
Transfer of loans into other investments		63,420	2,414
Investment in capital leases	12,467	16,123	8,184
Noncash assets acquired and liabilities assumed at fair value in business combination (Note 3):	0	¥ 0	¥ 0
Noncash assets acquired at fair value	93,049
Noncash Liabilities assumed at fair value	¥ 25,893

Basis of presentation and summa

Basis of presentation and summary of significant accounting policies	12 Months Ended
	Mar. 31, 2017
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”), Trust & Custody Services Bank, Ltd. (“TCSB”), 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. The MHFG Group has introduced an in-house The accompanying consolidated financial statements have been prepared in accordance with 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 and the fiscal year of certain subsidiaries ends on December 31. The necessary adjustments have been made to the consolidated financial statements if significant transactions took place during the three-month period. When determining whether to consolidate investee entities, the MHFG Group performed a careful 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 the 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. 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 due from banks For purposes of the consolidated statements of cash flows, Cash and due from banks includes cash on hand, cash items in the process of collection and noninterest-bearing deposits with banks. 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, 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 denominated in foreign currencies are translated into Japanese yen 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 9 “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 daily 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 4 “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 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”). 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 collectibility of the principal amount is uncertain, 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 5 “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 other obligors, the Group separately monitors the credit quality of each obligor without using time-based triggers. Subsequent recoveries of previously charged-off 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. In determining the appropriate level of the allowance, the MHFG Group evaluates the probable loss by category of loan based on its risk type and characteristics. 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 or listed securities. 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 small balance, homogeneous loans that are collectively evaluated for impairment and to non-homogeneous 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 within 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 back-tested on a periodic basis by comparing the allowance with the actual results subsequent to the balance sheet date. 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 Leasehold improvements 3 to 50 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 the accounts, and any gains or losses on disposal are included in Gains on disposal of premises and equipment or Occupancy expenses. 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 when triggering events occur. 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. An impairment loss is recorded to the extent the carrying amount of goodwill exceeds its estimated fair value. 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 among asset management companies consist primarily of customer relationship intangibles, and are amortized over weighted-average amortization periods of 16 years and 16.9 years, respectively. See Note 3 “Business Combination” for further details of the integration among asset management companies. 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. Pension and other employee benefits MHFG and certain subsidiaries sponsor severance indemnities and pension plans, which provide defined benefits to retired employees. Periodic expense and accrued liabilities are computed based on the actuarial present value of benefits, net of investment returns expected from plan assets and their fair values at the balance sheet date. Net periodic expense is charged to Salaries and employee benefits. Net actuarial gains and losses that arise from differences between actual experience and assumptions are generally amortized over the average remaining service period of participating employees if they exceed the corridor, which is defined as the greater of 10% of plan assets or the projected benefit obligation. Stock-based compensation The compensation cost with regard to stock options is measured at fair value using the Black-Scholes option pricing model. The compensation cost with regard to the performance-based stock compensation is determined based upon the fair value of the shares of MHFG common stock as of the grant date and is recognized over the three year deferral period on a straight-line basis. See Note 22 “Stock-based compensation” for further details of the stock options and the performance-based stock compensation. 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 28 “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 28 “Fair value” for descriptions of valuation methodologies used for its assets and liabilities by product. Fee and commission income Fee revenue is recognized when all of the following criteria have been met: persuasive evidence of an agreement exists, services have been rendered, the price is fixed or determinable, and collectibility is reasonably assured. Fees in respect of securities-related business and fees on funds transfer and collection services are generally recognized as revenue when the related services are performed. Fees on credit-related business, excluding loan origination fees which are deferred and recognized over the loan period as a yield adjustment, are generally recognized either at one time when the service is rendered or over the related transaction period. Fee and commission income is presented on a gross basis and exclusive of consumption taxes. Income taxes Income taxes are accounted for in accordance with ASC 740, “Income Taxes” (“ASC 740”). Deferred income taxes reflect the net tax effects of (1) temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the corresponding amounts used for income tax purposes, and (2) operating loss and tax credit carryforwards. A valuation allowance is recorded for any portion of the deferred tax assets unless it is more likely than not that the deferred tax assets will be realized. 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 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 the possible exercise of all convertible securities, such as convertible preferred stock to the extent they are not anti-dilutive. See Note 19 “Earnings per common share” for the computation of basic and diluted earnings per common share.

Recently issued accounting pron

Recently issued accounting pronouncements	12 Months Ended
	Mar. 31, 2017
Recently issued accounting pronouncements	2. Recently issued accounting pronouncements Recently adopted accounting pronouncements In June 2013, the FASB issued Accounting Standards Update (“ASU”) No.2013-08, No.2013-08”). In June 2014, the FASB issued ASU No.2014-11, 860)—Repurchase-to-Maturity No.2014-11”). repurchase-to-maturity repurchase-to-maturity In November 2014, the FASB issued ASU No.2014-16, No.2014-16”). No.2014-16 In February 2015, the FASB issued ASU No.2015-02, No.2015-02”). 2a-7 No.2015-02 In April 2015, the FASB issued ASU No.2015-03, 835-30)—Simplifying No.2015-03”). ASU No.2015-03 Long-term In May 2015, the FASB issued ASU No.2015-07, (“ASU No.2015-07”). No.2015-07 Accounting pronouncements issued but not yet effective In May 2014, the FASB issued ASU No.2014-09, (“ASU No.2014-09”). No.2015-14, No.2015-14”) ASU No.2014-09 No.2014-09 No.2014-09 No.2014-09 In January 2016, the FASB issued ASU No.2016-01, 825-10)—Recognition No.2016-01”). No.2016-01 In February 2016, the FASB issued ASU No.2016-02, No.2016-02”). right-of-use No.2016-02 In June 2016, the FASB issued ASU No.2016-13, No.2016-13”). available-for-sale No.2016-13 In October 2016, the FASB issued ASU No.2016-16, No.2016-16”). No.2016-16 In January 2017, the FASB issued ASU No.2017-04, No.2017-04”). ASU No. 2017-04 In May 2017, the FASB issued ASU No.2017-09, No.2017-09”). No. 2017-09

Business combination

Business combination	12 Months Ended
	Mar. 31, 2017
Business combination	3. Business combination Integration among asset management companies On October 1, 2016, DIAM Co., Ltd. (“DIAM”), MHTB, Mizuho Asset Management Co., Ltd. (“MHAM”) and Shinko Asset Management Co., Ltd. (“Shinko Asset Management”) (collectively, the “Integrating Companies”) integrated their asset management functions pursuant to an integration agreement signed on July 13, 2016. The integration was implemented through the following steps: (i) a merger between MHAM as surviving company and Shinko Asset Management as absorbed company; (ii) a company split between MHTB and MHAM (after the merger in (i) above) as successor company whereby rights and obligations attributed to Asset Management Division of MHTB were transferred to MHAM; and (iii) a merger between DIAM as surviving company and MHAM as absorbed company. After the integration, DIAM was renamed Asset Management One. As of September 30, 2016, MHAM was a wholly-owned subsidiary of MHFG and DIAM was an equity method affiliate of the MHFG Group which owned 50.0% of the voting equity interests. On October 1, 2016, MHFG exchanged 30.0% of the voting equity interests in MHAM (after the split in (ii) above) for voting equity interests and non-voting Based on the strong commitment of MHFG and Dai-ichi (“Dai-ichi Dai-ichi The following table summarizes the consideration paid for DIAM and the amounts of the acquired assets and assumed liabilities recognized at the acquisition date, as well as the fair value at the acquisition date of the noncontrolling interest in DIAM. There were no material acquisition-related costs that were recognized separately from the acquisition of the assets and the assumption of the liabilities. At October 1, (in millions of yen) Consideration: Equity instruments (1,038,408 common shares of MHAM) 28,842 Fair value of total consideration transferred 28,842 Fair value of equity interests in DIAM held by MHFG before the business 72,106 100,948 Recognized amounts of identifiable assets acquired: Cash and due from banks 831 Interest-bearing deposits in other banks 12,873 Trading account assets 266 Investments 12,234 Premises and equipment-net 3,546 Accrued income 7,882 Intangible assets (Note) 53,037 Deferred tax assets 1,003 Other assets 2,208 Recognized amounts of identifiable liabilities assumed: Trading account liabilities 304 Income taxes payable 918 Deferred taxes liabilities 16,238 Accrued expenses 5,392 Other liabilities 3,041 Total identifiable net assets 67,987 Goodwill 76,225 Noncontrolling interest in DIAM 43,264 100,948 Note: Amount represents customer relationships subject to amortization, of which the weighted-average amortization period is 16.9 years. The fair value of the equity interests in DIAM held by MHFG before the business combination (¥72,106 million), the fair value of the 1,038,408 common shares of MHAM as the consideration paid for DIAM (¥28,842 million) and the fair value of the noncontrolling interest in DIAM (¥43,264 million) were determined with reference to an independent third-party appraisal by applying the income approach and the market approach. The income approach was based on the discounted future cash flows of DIAM and MHAM and the market approach was based on market values, earnings and revenues of public companies comparable to DIAM and MHAM. A discount for lack of control was not considered in determining the fair value of the noncontrolling interest, which is entirely held by Dai-Ichi Dai-Ichi On October 1, 2016, the MHFG Group recognized a gain of ¥56,226 million as a result of remeasuring to fair value its 50.0% of the voting equity interests in DIAM held before the business combination. The gain is included in Other noninterest income in the Group’s consolidated statement of income for the fiscal year ended March 31, 2017. In addition, the MHFG Group recognized an increase in Common stock of ¥23,829 million as a result of remeasuring to fair value its 30.0% of the voting equity interests in MHAM held before the business combination due to the change in the voting equity interests in MHAM. The revenue and earnings of Asset Management One since the acquisition date included in the Group’s consolidated statement of income for the fiscal year ended March 31, 2017 are not material. Other than the gain of ¥56,226 million described above, the revenue and earnings of the MHFG Group would not have differed significantly from those reported in the consolidated statements of income for the fiscal years ended March 31, 2016 and 2017 if the business combination had occurred as of the beginning of the fiscal year ended March 31, 2016.

Investments

Investments	12 Months Ended
	Mar. 31, 2017
Investments	4. 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 Gross unrealized Fair value (in millions of yen) 2016 Available-for-sale Debt securities: Japanese government bonds 15,672,171 91,420 1,015 15,762,576 Japanese local government bonds 234,587 6,097 3 240,681 U.S. Treasury bonds and federal agency securities 436,792 1,720 32 438,480 Other foreign government bonds 939,808 2,740 153 942,395 Agency mortgage-backed securities (1) 920,375 29,804 1,293 948,886 Residential mortgage-backed securities 206,882 4,254 878 210,258 Commercial mortgage-backed securities 186,525 788 523 186,790 Japanese corporate bonds and other debt securities (2) 2,079,599 15,688 420 2,094,867 Foreign corporate bonds and other debt securities (3) 839,981 8,744 1,421 847,304 Equity securities (marketable) 1,663,486 2,121,379 4,577 3,780,288 Total 23,180,206 2,282,634 10,315 25,452,525 Held-to-maturity Debt securities: Japanese government bonds 3,760,032 56,620 — 3,816,652 Agency mortgage-backed securities (4) 1,058,929 3,894 6,266 1,056,557 Total 4,818,961 60,514 6,266 4,873,209 Amortized cost Gross unrealized Gross unrealized Fair value (in millions of yen) 2017 Available-for-sale Debt securities: Japanese government bonds 10,256,512 22,782 16,408 10,262,886 Japanese local government bonds 279,864 4,841 233 284,472 U.S. Treasury bonds and federal agency securities 1,148,389 10 4,578 1,143,821 Other foreign government bonds 933,942 1,246 236 934,952 Agency mortgage-backed securities (1) 832,738 15,500 5,441 842,797 Residential mortgage-backed securities 142,879 1,838 558 144,159 Commercial mortgage-backed securities 223,105 1,092 282 223,915 Japanese corporate bonds and other debt securities (2) 1,958,472 52,046 2,286 2,008,232 Foreign corporate bonds and other debt securities (3) 909,052 3,377 1,643 910,786 Equity securities (marketable) 1,528,808 2,273,883 1,593 3,801,098 Total 18,213,761 2,376,615 33,258 20,557,118 Held-to-maturity Debt securities: Japanese government bonds 3,059,976 37,168 — 3,097,144 Agency mortgage-backed securities (4) 757,384 121 7,931 749,574 Total 3,817,360 37,289 7,931 3,846,718 Notes : (1) Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥168,604 million and ¥780,282 million, respectively, at March 31, 2016, and ¥134,240 million and ¥708,557 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. (2) Other debt securities presented in the above table primarily consist of certificates of deposit (“CDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥158,446 million at March 31, 2016, and ¥155,138 million at March 31, 2017. (3) Other debt securities presented in the above table primarily consist of CDs, ABS, and collateralized loan obligations (“CLO”), of which the total fair values were ¥201,952 million at March 31, 2016, and ¥258,059 million at March 31, 2017. (4) All Agency mortgage-backed securities presented in the above table are Ginnie Mae securities. Contractual maturities The amortized cost and fair value of available-for-sale held-to-maturity Amortized cost Due in one Due after one Due after five Due after Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 3,147,992 5,538,724 1,569,796 — 10,256,512 Japanese local government bonds 41,307 101,307 136,701 549 279,864 U.S. Treasury bonds and federal agency securities 1,065,881 — 82,508 — 1,148,389 Other foreign government bonds 757,093 170,836 6,013 — 933,942 Agency mortgage-backed securities — — — 832,738 832,738 Residential mortgage-backed securities — — — 142,879 142,879 Commercial mortgage-backed securities 7,000 116,633 99,472 — 223,105 Japanese corporate bonds and other debt securities 471,592 866,455 431,097 189,328 1,958,472 Foreign corporate bonds and other debt securities 450,865 399,330 55,808 3,049 909,052 Total 5,941,730 7,193,285 2,381,395 1,168,543 16,684,953 Held-to-maturity Debt securities: Japanese government bonds 1,100,032 1,480,073 479,871 — 3,059,976 Agency mortgage-backed securities — — — 757,384 757,384 Total 1,100,032 1,480,073 479,871 757,384 3,817,360 Fair value Due in one Due after one Due after five Due after Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 3,151,367 5,549,293 1,562,226 — 10,262,886 Japanese local government bonds 41,366 102,326 140,138 642 284,472 U.S. Treasury bonds and federal agency securities 1,065,415 — 78,406 — 1,143,821 Other foreign government bonds 757,094 171,662 6,196 — 934,952 Agency mortgage-backed securities — — — 842,797 842,797 Residential mortgage-backed securities — — — 144,159 144,159 Commercial mortgage-backed securities 7,008 116,641 100,266 — 223,915 Japanese corporate bonds and other debt securities 472,047 869,226 433,132 233,827 2,008,232 Foreign corporate bonds and other debt securities 451,370 400,669 55,728 3,019 910,786 Total 5,945,667 7,209,817 2,376,092 1,224,444 16,756,020 Held-to-maturity Debt securities: Japanese government bonds 1,102,730 1,491,570 502,844 — 3,097,144 Agency mortgage-backed securities — — — 749,574 749,574 Total 1,102,730 1,491,570 502,844 749,574 3,846,718 Other-than-temporary impairment The MHFG Group performs periodic reviews to identify impaired securities in accordance with ASC 320, “Investments—Debt and Equity 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. For equity securities, impairment is evaluated considering the length of time and extent to which the fair value has been below cost, the financial condition and near-term prospects of the issuers, as well as the MHFG Group’s ability and intent to hold these investments for a reasonable period of time sufficient for a forecasted recovery of fair value. If an equity security is deemed other-than-temporarily impaired, it shall be written down to fair value, with the full decline recognized in earnings. The following table shows the other-than-temporary impairment losses on available-for-sale held-to-maturity 2015 2016 2017 (in millions of yen) Available-for-sale Debt securities 450 4,020 138 Equity securities 618 34,041 12,029 Total 1,068 38,061 12,167 For the fiscal year ended March 31, 2017, the other-than-temporary impairment losses on debt securities were attributable to the decline in the fair value of certain Japanese corporate bonds in respect of which the MHFG Group determined credit losses existed. In accordance with ASC 320-10-35-33A 320-10-35-34B, The other-than-temporary impairment losses on equity securities were mainly attributable to the decline in the fair value of certain Japanese equity securities. 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 Gross Fair Gross Fair Gross (in millions of yen) 2016 Available-for-sale Debt securities: Japanese government bonds 1,531,400 692 74,427 323 1,605,827 1,015 Japanese local government bonds 3,434 3 — — 3,434 3 U.S. Treasury bonds and federal agency securities 315,425 32 — — 315,425 32 Other foreign government bonds 225,493 139 225 14 225,718 153 Agency mortgage-backed securities (1) 15,965 86 58,147 1,207 74,112 1,293 Residential mortgage-backed securities 2,417 3 39,984 875 42,401 878 Commercial mortgage-backed securities 40,471 300 22,465 223 62,936 523 Japanese corporate bonds and other debt securities 360,782 348 20,109 72 380,891 420 Foreign corporate bonds and other debt securities 186,478 972 22,090 449 208,568 1,421 Equity securities (marketable) 71,262 4,515 180 62 71,442 4,577 Total 2,753,127 7,090 237,627 3,225 2,990,754 10,315 Held-to-maturity Debt securities: Agency mortgage-backed securities (2) 394,673 5,384 101,892 882 496,565 6,266 Total 394,673 5,384 101,892 882 496,565 6,266 2017 Available-for-sale Debt securities: Japanese government bonds 5,574,649 15,796 95,612 612 5,670,261 16,408 Japanese local government bonds 58,700 233 — — 58,700 233 U.S. Treasury bonds and federal agency securities 1,013,962 4,578 — — 1,013,962 4,578 Other foreign government bonds 334,300 230 8,327 6 342,627 236 Agency mortgage-backed securities (1) 195,887 3,705 42,501 1,736 238,388 5,441 Residential mortgage-backed securities 5,873 3 28,994 555 34,867 558 Commercial mortgage-backed securities 8,314 218 17,634 64 25,948 282 Japanese corporate bonds and other debt securities 470,602 2,062 158,713 224 629,315 2,286 Foreign corporate bonds and other debt securities 202,347 1,353 77,699 290 280,046 1,643 Equity securities (marketable) 30,688 383 4,117 1,210 34,805 1,593 Total 7,895,322 28,561 433,597 4,697 8,328,919 33,258 Held-to-maturity Debt securities: Agency mortgage-backed securities (2) 460,882 3,518 259,466 4,413 720,348 7,931 Total 460,882 3,518 259,466 4,413 720,348 7,931 Notes : (1) Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥69,805 million and ¥4,307 million, respectively, at March 31, 2016, and ¥134,118 million and ¥104,270 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. (2) All Agency mortgage-backed securities presented in the above table are Ginnie Mae securities. At March 31, 2017, 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, U.S. Treasury bonds and federal agency securities 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, including Japanese corporate bonds with similar credit risks as the other-than-temporarily impaired securities, 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, the MHFG Group determined that the debt securities in an unrealized loss position were not considered other-than-temporarily impaired. The equity securities in an unrealized loss position were determined not to be other-than-temporarily impaired based on the evaluation of the following factors: (1) the severity and duration of the impairments, (2) the financial condition and near-term prospects of the issuers, and (3) the MHFG Group’s ability and intent to hold these investments for a reasonable period of time sufficient for a forecasted recovery of fair value. Realized gains and losses The following table shows the realized gains and losses on sales of available-for-sale available-for-sale 2015 2016 2017 (in millions of yen) Gross realized gains 220,250 297,344 353,036 Gross realized losses (14,670 ) (45,376 ) (21,163 ) Net realized gains (losses) on sales of available-for-sale 205,580 251,968 331,873 Other investments The following table summarizes the composition of Other investments at March 31, 2016 and 2017: 2016 2017 (in millions of yen) Equity method investments 258,180 249,679 Investments held by consolidated investment companies 42,045 37,462 Other equity interests 313,221 307,928 Total 613,446 595,069 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 ¥124,830 million and ¥132,817 million, at March 31, 2016 and 2017, respectively. The aggregate market values of these marketable equity securities were ¥277,508 million and ¥273,249 million, respectively. The majority of the aggregate market values of these marketable equity securities are related to Orient Corporation, of which the MHFG Group’s proportionate share of the total outstanding common stock was 49.0% as of March 31, 2017. 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 Other equity interests Other equity interests primarily consist of non-marketable

Loans

Loans	12 Months Ended
	Mar. 31, 2017
Loans	5. Loans The table below presents loans outstanding by domicile and industry of borrower at March 31, 2016 and 2017: 2016 2017 (in millions of yen) Domestic: Manufacturing 8,344,808 8,740,281 Construction and real estate 7,733,513 7,654,016 Services 4,655,704 4,759,225 Wholesale and retail 5,408,850 5,142,003 Transportation and communications 3,267,902 3,490,415 Banks and other financial institutions 3,632,481 4,006,401 Government and public institutions 3,395,784 8,532,246 Other industries (Note) 4,619,336 4,427,349 Individuals: Mortgage loans 10,589,646 9,964,633 Other 924,408 939,971 Total domestic 52,572,432 57,656,540 Foreign: Commercial and industrial 17,319,284 16,872,448 Banks and other financial institutions 6,382,449 6,759,921 Government and public institutions 1,174,665 959,948 Other (Note) 273,695 190,724 Total foreign 25,150,093 24,783,041 Total 77,722,525 82,439,581 Less: Unearned income and deferred loan fees—net 167,156 155,675 Total loans before allowance for loan losses 77,555,369 82,283,906 Note: Other industries of Domestic and Other of Foreign include trade receivables and lease receivables of consolidated VIEs. Net losses on sales of loans were ¥33,291 million, ¥1,752 million and ¥919 million, including unrealized losses related to recording loans held for sale at the lower of cost or fair value of ¥34,262 million, ¥810 million, and ¥310 million for the fiscal years ended March 31, 2015, 2016 and 2017, respectively. 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 and pool allocations 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 groups of small balance, homogeneous loans. The Group pools loans with similar risk characteristics, and the risk is assessed 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 Obligor rating 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 (Note) 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. Note: Special attention obligors are watch obligors with debt in troubled debt restructuring (“TDR”) or 90 days or more delinquent debt. Loans to such obligors are considered impaired. The table below presents credit quality information of loans based on the MHFG Group’s internal rating system at March 31, 2016 and 2017: Normal obligors Watch obligors excluding (1) Impaired Total A-B C-D Retail (2) Other (3) E1-E2 Retail (2) Other (3) (in millions of yen) 2016 Domestic: Manufacturing 4,859,256 2,681,958 103,343 148,102 163,213 12,473 2,958 373,505 8,344,808 Construction and real estate 3,956,798 2,709,617 601,251 157,057 215,244 16,408 255 76,883 7,733,513 Services 2,611,296 1,674,328 195,140 2,380 81,704 24,846 — 66,010 4,655,704 Wholesale and retail 2,240,228 2,552,552 223,677 57,865 147,404 39,486 546 147,092 5,408,850 Transportation and communications 2,410,967 695,697 86,094 380 35,090 10,518 — 29,156 3,267,902 Banks and other financial institutions 2,719,047 881,405 2,234 3,788 22,303 264 — 3,440 3,632,481 Government and public institutions 3,181,241 4,047 — 210,496 — — — — 3,395,784 Other industries (4) 1,954,222 685,258 3,501 1,929,712 7,053 329 35,315 3,946 4,619,336 Individuals — 259,646 10,891,538 107,131 34,744 96,729 1,659 122,607 11,514,054 Total domestic 23,933,055 12,144,508 12,106,778 2,616,911 706,755 201,053 40,733 822,639 52,572,432 Foreign: Commercial and industrial 9,468,077 4,966,929 46 2,214,584 422,567 — 80,339 166,742 17,319,284 Banks and other financial institutions 5,129,904 550,380 — 656,969 45,196 — — — 6,382,449 Government and public institutions 942,366 224,514 — 2,940 4,801 — — 44 1,174,665 Other (4) — 6,308 8,336 258,363 132 10 268 278 273,695 Total foreign 15,540,347 5,748,131 8,382 3,132,856 472,696 10 80,607 167,064 25,150,093 Total 39,473,402 17,892,639 12,115,160 5,749,767 1,179,451 201,063 121,340 989,703 77,722,525 2017 Domestic: Manufacturing 5,313,232 2,599,760 90,825 67,734 276,771 11,589 1,314 379,056 8,740,281 Construction and real estate 4,199,022 2,641,436 558,321 15,585 165,836 16,023 317 57,476 7,654,016 Services 2,699,487 1,687,515 185,577 910 95,973 23,189 204 66,370 4,759,225 Wholesale and retail 2,244,214 2,369,842 200,003 22,785 124,846 32,911 501 146,901 5,142,003 Transportation and communications 2,584,367 739,781 82,543 1,092 50,319 9,698 — 22,615 3,490,415 Banks and other financial institutions 3,050,605 887,527 1,894 37,907 21,574 353 — 6,541 4,006,401 Government and public institutions 4,059,349 1,600 — 4,471,297 — — — — 8,532,246 Other industries (4) 1,873,137 591,109 3,535 1,906,756 4,613 410 41,179 6,610 4,427,349 Individuals — 289,809 10,312,739 80,566 26,288 89,066 1,434 104,702 10,904,604 Total domestic 26,023,413 11,808,379 11,435,437 6,604,632 766,220 183,239 44,949 790,271 57,656,540 Foreign: Commercial and industrial 9,310,432 4,814,906 173 2,153,757 312,275 — 90,722 190,183 16,872,448 Banks and other financial institutions 5,628,387 592,380 — 480,806 58,348 — — — 6,759,921 Government and public institutions 741,478 214,558 — 1,082 2,801 — — 29 959,948 Other (4) — 6,535 9,439 173,464 124 8 753 401 190,724 Total foreign 15,680,297 5,628,379 9,612 2,809,109 373,548 8 91,475 190,613 24,783,041 Total 41,703,710 17,436,758 11,445,049 9,413,741 1,139,768 183,247 136,424 980,884 82,439,581 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) Amounts represent small balance, homogeneous loans which are subject to pool allocations. (3) Non-impaired (4) Other industries of Domestic and Other of Foreign include trade receivables and lease receivables of consolidated VIEs. 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. 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, 2016 and 2017: Recorded investment (1) Unpaid Related (3) Average Interest (4) Requiring an Not (2) Total (in millions of yen) 2016 Domestic: Manufacturing 365,361 8,144 373,505 379,642 138,676 410,491 7,930 Construction and real estate 59,883 17,000 76,883 87,516 10,130 89,075 1,246 Services 56,695 9,315 66,010 72,603 19,095 69,525 1,292 Wholesale and retail 134,425 12,667 147,092 157,215 46,304 149,324 2,376 Transportation and communications 25,665 3,491 29,156 30,497 5,694 33,119 630 Banks and other financial institutions 3,390 50 3,440 3,440 1,095 5,188 42 Other industries 3,591 355 3,946 4,132 799 2,665 64 Individuals 63,367 59,240 122,607 135,325 6,085 133,015 2,058 Total domestic 712,377 110,262 822,639 870,370 227,878 892,402 15,638 Foreign: Total foreign 148,471 18,593 167,064 180,870 61,308 186,440 2,629 Total 860,848 128,855 989,703 1,051,240 289,186 1,078,842 18,267 2017 Domestic: Manufacturing 372,241 6,815 379,056 383,812 148,777 375,895 2,859 Construction and real estate 46,130 11,346 57,476 66,006 6,367 66,796 877 Services 58,366 8,004 66,370 72,261 20,122 66,050 1,173 Wholesale and retail 133,466 13,435 146,901 155,023 52,341 148,865 2,261 Transportation and communications 19,386 3,229 22,615 23,568 5,968 24,035 371 Banks and other financial institutions 2,601 3,940 6,541 6,873 962 5,305 50 Other industries 6,484 126 6,610 6,740 1,999 6,053 91 Individuals 51,893 52,809 104,702 114,880 4,935 114,104 1,696 Total domestic 690,567 99,704 790,271 829,163 241,471 807,103 9,378 Foreign: Total foreign 160,563 30,050 190,613 209,129 61,102 169,192 2,040 Total 851,130 129,754 980,884 1,038,292 302,573 976,295 11,418 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 small balance, homogeneous 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 small balance, homogeneous loans at March 31, 2016 and 2017 was ¥347,839 million and ¥302,251 million, respectively. (4) Amounts represent gross interest income on impaired loans which were included in Interest income on loans in the consolidated statements of income. The remaining balance of impaired loans which had been partially charged off was ¥31,933 million and ¥26,513 million as of March 31, 2016 and 2017, respectively. Troubled debt restructurings The MHFG Group considers a TDR to be a restructuring in which it, for economic or legal reasons related to the obligor’s financial difficulties, grants a concession to the obligor that it would not otherwise consider. The Group considers the relevant obligor to be in financial difficulty when its obligor rating is E2 or below. The following table presents TDRs that were entered into during the fiscal years ended March 31, 2016 and 2017: Loan forgiveness or debt to Interest rate Recorded (Note ) Charge-offs (in millions of yen) 2016 Domestic: Manufacturing 67,058 34,081 108,395 Construction and real estate — — 27,078 Services — — 43,919 Wholesale and retail — — 157,651 Transportation and communications 49 279 28,244 Banks and other financial institutions — — 6,342 Other industries — — 7,120 Individuals — — 28,163 Total domestic 67,107 34,360 406,912 Foreign: Total foreign — — 44,748 Total 67,107 34,360 451,660 2017 Domestic: Manufacturing — — 106,697 Construction and real estate — — 18,818 Services — — 45,287 Wholesale and retail — — 159,649 Transportation and communications — — 17,417 Banks and other financial institutions — — 7,933 Other industries — — 2,518 Individuals — — 17,067 Total domestic — — 375,386 Foreign: Total foreign — — 35,685 Total — — 411,071 Note: Amounts represent the book values of loans immediately after the restructurings. 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, 2016 and 2017 with respect to the loans modified as TDRs within the previous twelve months: Recorded investment 2016 2017 (in millions of yen) Domestic: Manufacturing 10,669 5,164 Construction and real estate 2,195 2,887 Services 4,824 4,471 Wholesale and retail 20,522 10,116 Transportation and communications 2,361 795 Other industries — 14 Individuals 3,864 2,288 Total domestic 44,435 25,735 Foreign: Total foreign 10,846 3,213 Total 55,281 28,948 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, 2016 and 2017: 30-59 days 60-89 days 90 days or Total past Current Total (in millions of yen) 2016 Domestic: Manufacturing 1,555 163 9,454 11,172 8,333,636 8,344,808 Construction and real estate 2,713 1,024 35,691 39,428 7,694,085 7,733,513 Services 2,479 223 7,016 9,718 4,645,986 4,655,704 Wholesale and retail 3,193 886 8,861 12,940 5,395,910 5,408,850 Transportation and communications 594 81 2,033 2,708 3,265,194 3,267,902 Banks and other financial institutions — — — — 3,632,481 3,632,481 Government and public institutions — — — — 3,395,784 3,395,784 Other industries — — 29 29 4,619,307 4,619,336 Individuals 38,682 13,570 38,413 90,665 11,423,389 11,514,054 Total domestic 49,216 15,947 101,497 166,660 52,405,772 52,572,432 Foreign: Total foreign 859 2,598 30,000 33,457 25,116,636 25,150,093 Total 50,075 18,545 131,497 200,117 77,522,408 77,722,525 2017 Domestic: Manufacturing 1,938 360 7,767 10,065 8,730,216 8,740,281 Construction and real estate 2,818 947 32,523 36,288 7,617,728 7,654,016 Services 917 217 5,914 7,048 4,752,177 4,759,225 Wholesale and retail 1,330 2,834 5,585 9,749 5,132,254 5,142,003 Transportation and communications 384 322 1,859 2,565 3,487,850 3,490,415 Banks and other financial institutions — — — — 4,006,401 4,006,401 Government and public institutions — — — — 8,532,246 8,532,246 Other industries — — 69 69 4,427,280 4,427,349 Individuals 32,995 12,291 34,846 80,132 10,824,472 10,904,604 Total domestic 40,382 16,971 88,563 145,916 57,510,624 57,656,540 Foreign: Total foreign 546 216 95,719 96,481 24,686,560 24,783,041 Total 40,928 17,187 184,282 242,397 82,197,184 82,439,581

Allowance for loan losses

Allowance for loan losses	12 Months Ended
	Mar. 31, 2017
Allowance for loan losses	6. 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 Changes in Allowance for loan losses by portfolio segment for the fiscal years ended March 31, 2015, 2016 and 2017 are shown below: Corporate Retail Other Total (in millions of yen) 2015 Balance at beginning of fiscal year 501,349 95,542 29,286 626,177 Provision (credit) for loan losses (40,167 ) (33,261 ) 13,205 (60,223 ) Charge-offs (64,634 ) (3,266 ) (11,322 ) (79,222 ) Recoveries 19,086 1,454 2,743 23,283 Net charge-offs (45,548 ) (1,812 ) (8,579 ) (55,939 ) Others (Note) 7,543 — 2,701 10,244 Balance at end of fiscal year 423,177 60,469 36,613 520,259 2016 Balance at beginning of fiscal year 423,177 60,469 36,613 520,259 Provision (credit) for loan losses 33,532 (15,474 ) 16,502 34,560 Charge-offs (97,536 ) (2,173 ) (12,610 ) (112,319 ) Recoveries 17,232 1,399 2,034 20,665 Net charge-offs (80,304 ) (774 ) (10,576 ) (91,654 ) Others (Note) (8,666 ) — (3,252 ) (11,918 ) Balance at end of fiscal year 367,739 44,221 39,287 451,247 2017 Balance at beginning of fiscal year 367,739 44,221 39,287 451,247 Provision (credit) for loan losses 45,059 (10,666 ) 3,275 37,668 Charge-offs (22,901 ) (1,754 ) (6,597 ) (31,252 ) Recoveries 18,320 5,122 2,158 25,600 Net charge-offs (4,581 ) 3,368 (4,439 ) (5,652 ) Others (Note) (890 ) — (2,700 ) (3,590 ) Balance at end of fiscal year 407,327 36,923 35,423 479,673 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, 2016 and 2017: Corporate Retail Other Total (in millions of yen) 2016 Allowance for loan losses 367,739 44,221 39,287 451,247 of which individually evaluated for impairment 222,591 3,829 12,521 238,941 of which collectively evaluated for impairment 145,148 40,392 26,766 212,306 Loans (Note) 59,385,962 12,414,453 5,922,110 77,722,525 of which individually evaluated for impairment 634,049 24,768 63,280 722,097 of which collectively evaluated for impairment 58,751,913 12,389,685 5,858,830 77,000,428 2017 Allowance for loan losses 407,327 36,923 35,423 479,673 of which individually evaluated for impairment 272,714 2,922 13,306 288,942 of which collectively evaluated for impairment 134,613 34,001 22,117 190,731 Loans (Note) 61,120,654 11,722,726 9,596,201 82,439,581 of which individually evaluated for impairment 772,647 23,422 65,075 861,144 of which collectively evaluated for impairment 60,348,007 11,699,304 9,531,126 81,578,437 Note: Amounts represent loan balances before deducting unearned income and deferred loan fees. In the fiscal year ended March 31, 2015, Credit for loan losses decreased by ¥66,007 million from the previous fiscal year. The decrease was due primarily to an increase in allowance for loan losses on impaired loans related to certain domestic borrowers, although the MHFG Group continued to record a credit for loan losses and recorded a decrease in allowance for loan losses on non-impaired In the fiscal year ended March 31, 2016, Provision for loan losses increased by ¥94,783 million from the previous fiscal year. The MHFG Group recorded a modest level of Provision for loan losses, reflecting how the Japanese economy was in a “leveling off” phase. In the fiscal year ended March 31, 2017, Provision for loan losses increased by ¥3,108 million from the previous fiscal year. Although obligor categories improved as a whole, reflecting the gradual recovery in the economic environment, Provision for loan losses increased due mainly to the deterioration of credit status of certain borrowers.

Premises and equipment

Premises and equipment	12 Months Ended
	Mar. 31, 2017
Premises and equipment	7. Premises and equipment Premises and equipment at March 31, 2016 and 2017 consist of the following: 2016 2017 (in millions of yen) Land 552,205 575,054 Buildings 827,458 807,312 Equipment and furniture 463,205 485,407 Leasehold improvements 88,195 93,967 Construction in progress 20,656 23,093 Software 1,086,124 1,308,292 Total 3,037,843 3,293,125 Less: Accumulated depreciation and amortization 1,199,853 1,251,852 Premises and equipment—net 1,837,990 2,041,273 Depreciation and amortization expense for premises and equipment for the fiscal years ended March 31, 2015, 2016 and 2017 was ¥161,152 million, ¥162,676 million and ¥163,769 million, respectively. Premises and equipment under capital leases, which is primarily comprised of data processing equipment, amounted to ¥69,077 million and ¥80,430 million at March 31, 2016 and 2017, respectively. Accumulated depreciation and amortization on such premises and equipment at March 31, 2016 and 2017 amounted to ¥34,733 million and ¥40,155 million, respectively.

Goodwill and intangible assets

Goodwill and intangible assets	12 Months Ended
	Mar. 31, 2017
Goodwill and intangible assets	8. Goodwill and intangible assets Goodwill The changes in Goodwill during the fiscal years ended March 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 (in millions of yen) Balance at beginning of fiscal year 11,549 11,703 19,097 Goodwill acquired — 16,470 (1) 76,225 (2) Impairment losses recognized — (6,222 ) — Foreign exchange translation 154 (2,854 ) (146 ) Balance at end of fiscal year 11,703 19,097 95,176 Gross amount of goodwill (3) 81,254 94,473 171,432 Accumulated impairment losses 69,551 75,376 76,256 Notes: (1) Goodwill acquired is entirely related to the acquisition of Simplex Real Estate Management Inc. and Simplex REIT Partners Inc. (2) Goodwill acquired is entirely related to the acquisition of Asset Management One (see Note 3 “Business combination”). (3) 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 32 “Business segment information”. Due to the prolonged severe business environment for Banco Mizuho do Brasil S.A., it was determined that the carrying amount of the Banco Mizuho do Brasil S.A. reporting unit exceeded its fair value, which is based on the market approach. Therefore, a goodwill impairment loss of ¥6,222 million was recognized during the fiscal year ended March 31, 2016. Intangible assets The table below presents the gross carrying amount, accumulated amortization and net carrying amount of intangible assets, at March 31, 2016 and 2017: 2016 2017 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) 73,949 35,178 38,771 126,979 42,517 84,462 Other 2,864 2,208 656 2,814 2,190 624 Total 76,813 37,386 39,427 129,793 44,707 85,086 Intangible assets not subject to amortization: Total 9,224 — 9,224 9,061 — 9,061 Total 86,037 37,386 48,651 138,854 44,707 94,147 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 3 “Business combination” for further details of the integration among asset management companies. See Note 1 “Basis of presentation and summary of significant accounting policies” for further information. For the fiscal years ended March 31, 2015, 2016, and 2017, the MHFG Group recognized ¥5,376 million, ¥5,254 million, and ¥7,433 million, respectively, of 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: 2018 9,465 2019 9,243 2020 8,940 2021 8,232 2022 7,699

Pledged assets and collateral

Pledged assets and collateral	12 Months Ended
	Mar. 31, 2017
Pledged assets and collateral	9. 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, 2016 and 2017: 2016 2017 (in billions of yen) Interest-bearing deposits in other banks 69 51 Trading account assets 7,939 6,577 Investments 10,254 8,213 Loans 5,871 7,468 Other assets 1,322 1,588 Total 25,455 23,897 The associated liabilities collateralized by the above assets at March 31, 2016 and 2017 are summarized below: 2016 2017 (in billions of yen) Deposits 813 919 Payables under repurchase agreements 6,182 6,109 Payables under securities lending transactions 2,790 1,460 Other short-term borrowings 657 686 Long-term debt 5,545 4,220 Total 15,987 13,394 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. At March 31, 2016 and 2017, 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 ¥34,377 billion and ¥44,741 billion, respectively. These balances included the reserve funds required to be maintained by the MHFG Group, which amounted to ¥1,322 billion and ¥1,462 billion at March 31, 2016 and 2017, respectively. At March 31, 2016 and 2017, the MHFG Group had received collateral that can be sold or repledged, with a fair value of ¥12,116 billion and ¥13,395 billion, respectively, of which ¥11,616 billion and ¥12,988 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.

Deposits

Deposits	12 Months Ended
	Mar. 31, 2017
Deposits	10. Deposits The balances of time deposits and certificates of deposit issued by domestic offices in amounts of ¥10 million (approximately US$90 thousand at the Federal Reserve Bank of New York’s noon buying rate on March 31, 2017) or more and the balances of these deposits issued by foreign offices in amounts of US$100,000 or more at March 31, 2016 and 2017 are as follows: 2016 2017 (in millions of yen) Domestic offices: Time deposits 19,209,570 17,763,052 Certificates of deposit 6,432,810 5,877,100 Total 25,642,380 23,640,152 Foreign offices: Time deposits 12,708,142 14,862,230 Certificates of deposit 5,394,695 4,754,170 Total 18,102,837 19,616,400 The aggregate amount of demand deposits in overdraft status that have been reclassified as loan balances at March 31, 2016 and 2017 was ¥890 billion and ¥718 billion, respectively. The balance and remaining maturities of time deposits and certificates of deposit issued by domestic and foreign offices at March 31, 2017 are shown in the following table: Time deposits Certificates of deposit Total (in millions of yen) Domestic offices: Due in one year or less 22,800,247 5,821,000 28,621,247 Due after one year through two years 2,024,310 56,100 2,080,410 Due after two years through three years 1,206,888 — 1,206,888 Due after three years through four years 349,896 — 349,896 Due after four years through five years 346,569 — 346,569 Due after five years 133,581 — 133,581 Total 26,861,491 5,877,100 32,738,591 Foreign offices: Due in one year or less 14,765,251 4,599,583 19,364,834 Due after one year through two years 88,304 38,709 127,013 Due after two years through three years 5,740 55,818 61,558 Due after three years through four years — 60,067 60,067 Due after four years through five years 198 — 198 Due after five years 8,956 — 8,956 Total 14,868,449 4,754,177 19,622,626 Total 41,729,940 10,631,277 52,361,217

Due to trust accounts

Due to trust accounts	12 Months Ended
	Mar. 31, 2017
Due to trust accounts	11. Due to trust accounts MHTB and TCSB, which are MHFG’s trust bank subsidiaries, hold assets on behalf of their 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 and TCSB for the customers’ short-term investment needs. These amounts which MHTB and TCSB owe to the trust accounts are recorded as Due to trust accounts. The MHFG Group consolidates certain guaranteed principal money trusts. See Note 25 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts.

Short-term borrowings and long-

Short-term borrowings and long-term debt	12 Months Ended
	Mar. 31, 2017
Short-term borrowings and long-term debt	12. Short-term borrowings and long-term 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, 2016 and 2017 are as follows: 2016 2017 (in millions of yen) Commercial paper and short-term notes issued by consolidated VIEs of asset-backed commercial paper programs (1) (2) 289,219 59,607 Commercial paper and short-term notes issued by MHFG and its subsidiaries (1) (3) 1,369,302 956,447 Borrowings from the Bank of Japan 324,146 355,255 Other 97,372 105,303 Total 2,080,039 1,476,612 Notes: (1) Short-term notes are issued under the laws of Japan in the form of dematerialized commercial paper, whose characteristics are economically the same as commercial paper. (2) Commercial paper and short-term notes issued by consolidated VIEs of asset-backed commercial paper programs in the above table consist of commercial paper and short-term notes, of which the amounts were ¥232,538 million and ¥56,681 million, respectively, at March 31, 2016, and ¥24,559 million and ¥35,048 million, respectively, at March 31, 2017. (3) Commercial paper and short-term notes issued by MHFG and its subsidiaries in the above table consist of commercial paper and short-term notes, of which the amounts were ¥777,602 million and ¥591,700 million, respectively, at March 31, 2016, and ¥765,147 million and ¥191,300 million, respectively, at March 31, 2017. Long-term debt Long-term debt with original maturities of more than one year at March 31, 2016 and 2017 is comprised of the following: 2016 2017 (in millions of yen) Obligations under capital leases 37,811 40,947 Loan participation borrowings 64,524 90,639 Senior borrowings and bonds 11,576,384 11,119,136 Subordinated borrowings and bonds 3,086,808 3,278,692 Total 14,765,527 14,529,414 The following table presents the interest rates and maturities of senior borrowings and bonds, and subordinated borrowings and bonds: Interest rates (1) Maturities (2) 2016 2017 (%) (in millions of yen) Senior borrowings and bonds: fixed rate denominated in Japanese yen 0.00-10.00 Apr. 2017-Dec. 2046 7,863,984 6,011,939 fixed rate denominated in U.S. dollars 0.00-7.49 Apr. 2017-Aug. 2046 1,778,892 2,533,715 fixed rate denominated in other currencies 0.01-10.00 Apr. 2017-May. 2037 135,515 172,370 floating rate denominated in Japanese yen 0.00-23.80 Apr. 2017-Mar. 852,425 717,056 floating rate denominated in U.S. dollars 0.00-10.00 Apr. 2017-Jul. 898,840 1,557,288 floating rate denominated in other currencies 0.00-9.40 Aug. 2017-Sep. 46,728 126,768 Total 11,576,384 11,119,136 Subordinated borrowings and bonds: fixed rate denominated in Japanese yen 0.50-4.26 Apr. 2017-Perpetual 2,596,460 2,858,445 fixed rate denominated in U.S. dollars 4.30-4.70 Jul. 2022-Oct. 490,348 420,247 Total 3,086,808 3,278,692 Total 14,663,192 14,397,828 Notes: (1) The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2017. (2) Maturity information disclosed is the range of maturities at March 31, 2017. (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 the contractual maturities of long-term debt subsequent to March 31, 2017: (in millions of yen) Fiscal year ending March 31: 2018 1,614,386 2019 3,127,227 2020 1,733,501 2021 1,841,416 2022 1,194,536 2023 and thereafter 5,018,348 Total 14,529,414

Other assets and liabilities

Other assets and liabilities	12 Months Ended
	Mar. 31, 2017
Other assets and liabilities	13. Other assets and liabilities The following table sets forth the details of other assets and liabilities at March 31, 2016 and 2017: 2016 2017 (in millions of yen) Other assets: Accounts receivable from brokers, dealers and customers for securities transactions 1,718,769 1,564,295 Collateral provided for derivative transactions 884,651 973,404 Prepaid pension cost 612,102 682,592 Miscellaneous receivables 286,896 324,135 Margins provided for futures contracts 225,240 276,398 Security deposits 113,066 122,858 Loans held for sale 33,133 26,689 Other 823,033 1,021,958 Total 4,696,890 4,992,329 Other liabilities: Accounts payable to brokers, dealers and customers for securities transactions 2,882,824 1,400,141 Guaranteed trust principal 623,904 683,324 Collateral accepted for derivative transactions 715,894 671,691 Miscellaneous payables 442,352 481,809 Margins accepted for futures contracts 334,925 307,066 Unearned income 144,903 134,666 Factoring amounts owed to customers 242,392 53,488 Other 1,089,529 1,294,340 Total 6,476,723 5,026,525 Guaranteed trust principal Guaranteed trust principal is the liability of certain consolidated trust arrangements, in respect of which the MHFG Group provides guarantees for the repayment of principal. See Note 25 “Variable interest entities and securitizations” for further discussion of the guaranteed principal money trusts. Unearned income Unearned income is primarily comprised of refundable fees received from consumer loan customers at the time the loans were made, which is being deferred and recognized in earnings as earned.

Preferred stock

Preferred stock	12 Months Ended
	Mar. 31, 2017
Preferred stock	14. Preferred stock The composition of preferred stock at March 31, 2015, 2016 and 2017 is as follows: 2015 Aggregate amount Number of shares Liquidation Convertible Class of stock Authorized Issued In treasury (in millions of yen) (in yen) Eleventh series class XI preferred stock (1) 914,752 914,752,000 914,752,000 701,631,100 1,000 Yes First series class XIV preferred stock (2) — 900,000,000 — — — — Second series class XIV preferred stock (2) — 900,000,000 — — — — Third series class XIV preferred stock (2) — 900,000,000 — — — — Fourth series class XIV preferred stock (2) — 900,000,000 — — — — First series class XV preferred stock (3) — 900,000,000 — — — — Second series class XV preferred stock (3) — 900,000,000 — — — — Third series class XV preferred stock (3) — 900,000,000 — — — — Fourth series class XV preferred stock (3) — 900,000,000 — — — — First series class XVI preferred stock (4) — 1,500,000,000 — — — — Second series class XVI preferred stock (4) — 1,500,000,000 — — — — Third series class XVI preferred stock (4) — 1,500,000,000 — — — — Fourth series class XVI preferred stock (4) — 1,500,000,000 — — — — Total 914,752 4,214,752,000 914,752,000 701,631,100 2016 Aggregate amount Number of shares Liquidation Convertible Class of stock Authorized Issued In treasury (in millions of yen) (in yen) Eleventh series class XI preferred stock (1) 914,752 914,752,000 914,752,000 815,828,400 1,000 Yes First series class XIV preferred stock (2) — 900,000,000 — — — — Second series class XIV preferred stock (2) — 900,000,000 — — — — Third series class XIV preferred stock (2) — 900,000,000 — — — — Fourth series class XIV preferred stock (2) — 900,000,000 — — — — First series class XV preferred stock (3) — 900,000,000 — — — — Second series class XV preferred stock (3) — 900,000,000 — — — — Third series class XV preferred stock (3) — 900,000,000 — — — — Fourth series class XV preferred stock (3) — 900,000,000 — — — — First series class XVI preferred stock (4) — 1,500,000,000 — — — — Second series class XVI preferred stock (4) — 1,500,000,000 — — — — Third series class XVI preferred stock (4) — 1,500,000,000 — — — — Fourth series class XVI preferred stock (4) — 1,500,000,000 — — — — Total 914,752 4,214,752,000 914,752,000 815,828,400 2017 Aggregate amount Number of shares Liquidation Convertible Class of stock Authorized Issued In treasury (in millions of yen) (in yen) Class XI preferred stock — 914,752,000 — — — — First series class XIV preferred stock (2) — 900,000,000 — — — — Second series class XIV preferred stock (2) — 900,000,000 — — — — Third series class XIV preferred stock (2) — 900,000,000 — — — — Fourth series class XIV preferred stock (2) — 900,000,000 — — — — First series class XV preferred stock (3) — 900,000,000 — — — — Second series class XV preferred stock (3) — 900,000,000 — — — — Third series class XV preferred stock (3) — 900,000,000 — — — — Fourth series class XV preferred stock (3) — 900,000,000 — — — — First series class XVI preferred stock (4) — 1,500,000,000 — — — — Second series class XVI preferred stock (4) — 1,500,000,000 — — — — Third series class XVI preferred stock (4) — 1,500,000,000 — — — — Fourth series class XVI preferred stock (4) — 1,500,000,000 — — — — Total — 4,214,752,000 — — Notes: (1) The aggregate amount and number of issued shares include the preferred stock in treasury which has been converted into common stock but not yet cancelled. (2) The total number of authorized shares from first to fourth series class XIV preferred stock shall not exceed 900,000,000. (3) The total number of authorized shares from first to fourth series class XV preferred stock shall not exceed 900,000,000. (4) The total number of authorized shares from first to fourth series class XVI preferred stock shall not exceed 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 In June 2013, MHFG newly authorized class XIV preferred stock, class XV preferred stock and class XVI preferred stock to meet the requirements of Basel III. Under Basel III, in order for preferred stock issued by a bank holding company to be included as its regulatory capital under the capital adequacy requirements, the terms and conditions of the preferred stock are required to include a provision that in the event the bank holding company is considered to be non-viable, write-off The following table shows the changes in the number of shares and the aggregate amount of preferred stock during the fiscal years ended March 31, 2015, 2016 and 2017: Class of stock Issued at Net Issued at Net Issued at Net Issued at (number of shares) Eleventh series class XI preferred stock (Note) 914,752,000 — 914,752,000 — 914,752,000 (914,752,000 ) — Total 914,752,000 — 914,752,000 — 914,752,000 (914,752,000 ) — Class of stock Aggregate Net Aggregate Net Aggregate Net Aggregate (in millions of yen) Eleventh series class XI preferred stock (Note) 914,752 — 914,752 — 914,752 (914,752 ) — Total 914,752 — 914,752 — 914,752 (914,752 ) — Note: In July 2016, all shares of the eleventh series class XI preferred stock were converted into common stock and cancelled.

Common stock

Common stock	12 Months Ended
	Mar. 31, 2017
Common stock	15. Common stock The following table shows the changes in the number of issued shares of common stock during the fiscal years ended March 31, 2015, 2016 and 2017: 2015 2016 2017 (shares) Balance at beginning of fiscal year 24,263,885,187 24,621,897,967 25,030,525,657 Issuance of new shares of common stock due to conversion of Eleventh series class XI preferred stock 351,822,780 403,667,690 349,677,288 Issuance of new shares of common stock due to exercise of stock acquisition rights 6,190,000 4,960,000 6,105,000 Balance at end of fiscal year 24,621,897,967 25,030,525,657 25,386,307,945

Dividends

Dividends	12 Months Ended
	Mar. 31, 2017
Dividends	16. Dividends The amount available for dividends under the Companies Act is based on the amount recorded in MHFG’s non-consolidated period-end In making a distribution of retained earnings, an entity must set aside in its legal reserve an amount equal to one-tenth one-quarter In addition to the provision that requires an appropriation for the legal reserve, the Companies Act and the 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, 2017, was ¥1,831,321 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 18 “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. The following table shows dividends on preferred stock and common stock during the fiscal years ended March 31, 2015, 2016 and 2017: 2015 Cash dividends Class of stock Per share In aggregate (in yen) (in millions of yen) Eleventh series class XI preferred stock 20 5,906 Common stock 7 170,231 Total 176,137 2016 Cash dividends Class of stock Per share In aggregate (in yen) (in millions of yen) Eleventh series class XI preferred stock 20 3,572 Common stock 7.75 191,693 Total 195,265 2017 Cash dividends Class of stock Per share In aggregate (in yen) (in millions of yen) Eleventh series class XI preferred stock (Note) 10 989 Common stock 7.50 189,013 Total 190,002 Note: In July 2016, all shares of the eleventh series class XI preferred stock were converted into common stock and cancelled. Consequently, the amount for the fiscal year does not include interim dividends.

Accumulated other comprehensive

Accumulated other comprehensive income	12 Months Ended
	Mar. 31, 2017
Accumulated other comprehensive income	17. Accumulated other comprehensive income Changes in each component of AOCI for the fiscal years ended March 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 (in millions of yen) AOCI, balance at beginning of fiscal year, previously reported 1,117,877 2,041,005 1,469,308 Cumulative effect of change in accounting principles (Notes 2 and 25) — — 330 AOCI, balance at beginning of fiscal year, adjusted 1,117,877 2,041,005 1,469,638 Net unrealized gains (losses) on available-for-sale Balance at beginning of fiscal year, previously reported 1,123,272 1,747,607 1,409,459 Cumulative effect of change in accounting principles — — (85 ) Balance at beginning of fiscal year, adjusted 1,123,272 1,747,607 1,409,374 Unrealized holding gains (losses) during year 763,115 (189,479 ) 273,844 Less: reclassification adjustments for losses (gains) included in net income (138,780 ) (148,669 ) (221,916 ) Change during year 624,335 (338,148 ) 51,928 Balance at end of fiscal year 1,747,607 1,409,459 1,461,302 Foreign currency translation adjustments: Balance at beginning of fiscal year, previously reported (6,434 ) 129,179 6,310 Cumulative effect of change in accounting principles — — 415 Balance at beginning of fiscal year, adjusted (6,434 ) 129,179 6,725 Foreign currency translation adjustments during year 134,104 (122,081 ) (11,920 ) Less: reclassification adjustments for losses (gains) included in net income 1,509 (788 ) (340 ) Change during year 135,613 (122,869 ) (12,260 ) Balance at end of fiscal year 129,179 6,310 (5,535 ) Pension liability adjustments: Balance at beginning of fiscal year, previously reported 1,039 164,219 53,539 Unrealized gains (losses) during year 163,191 (107,497 ) 11,561 Less: reclassification adjustments for losses (gains) included in net income (11 ) (3,183 ) 296 Change during year 163,180 (110,680 ) 11,857 Balance at end of fiscal year 164,219 53,539 65,396 Total other comprehensive income (loss), net of tax attributable to MHFG shareholders 923,128 (571,697 ) 51,525 AOCI, balance at end of fiscal year 2,041,005 1,469,308 1,521,163 The following table shows the amounts reclassified out of AOCI into net income during the fiscal year ended March 31, 2017: Before tax (1) Tax effect (2) Net of tax before Net of tax attributable to (2) Net of tax attributable 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 319,707 (97,729 ) 221,978 (62 ) 221,916 Investment gains (losses)—net Foreign currency translation adjustments 340 — 340 — 340 Foreign exchange gains (losses)-net Pension liability adjustments (476 ) 178 (298 ) 2 (296 ) Salaries and employee benefits Total 319,571 (97,551 ) 222,020 (60 ) 221,960 Notes: (1) The amounts in the Before tax column are recorded in each account presented under the heading “Affected line items in the consolidated statements of income”. (2) The amounts in the Tax effect column and Net of tax attributable to noncontrolling interests column are recorded in Income tax expense and Net income (loss) attributable to noncontrolling interests in the consolidated statements of income, respectively.

Regulatory matters

Regulatory matters	12 Months Ended
	Mar. 31, 2017
Regulatory matters	18. 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 the Banking Act and related regulations. 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 Basel Committee on Banking Supervision (“BCBS”) and are intended to further strengthen the soundness and stability of Japanese banks. In December 2010, BCBS issued the Basel III rules text (later revised in June 2011, January 2013 and October 2014), which presents the details of global regulatory standards on bank capital adequacy and liquidity agreed by the Governors and Heads of Supervision, which is the oversight body of BCBS, and endorsed by the G20 Leaders at the Seoul summit in November 2010. 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, and the introduction of the capital conservation buffer and countercyclical capital buffer as measures to promote the build-up of capital that can be drawn down in periods of stress, and the introduction of two global liquidity standards. 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 rules text that have been applied from January 1, 2013. The framework of Basel III is based on the following three pillars: minimum capital requirements; supervisory review; and market discipline. Under the first pillar, the capital ratio is calculated by dividing regulatory capital, or risk-based capital, by risk-weighted assets. Under the second pillar, banks are required to maintain adequate capital to support all of the major risks in their business and are encouraged to develop and use better risk management techniques in monitoring and managing such risks. Under the third pillar, banks are required to enhance disclosure, including disclosure of details of the capital adequacy ratio, the amount of each type of risk and the method of calculation used so that the market may make more effective evaluations. With regard to risk-based capital, the guidelines based on Basel III set out higher and better-quality capital standards compared to those under Basel II, which had been effective until Basel III was applied. The guidelines based on Basel III require a target minimum standard capital adequacy ratio of 8%, Tier 1 capital ratio of 6% and Common Equity Tier 1 capital ratio of 4.5%, on both a consolidated and non-consolidated Risk-based capital, calculated from financial statements prepared under Japanese GAAP, is classified into the following two tiers: Tier 1 capital; and Tier 2 capital. Tier 1 capital consists of Common Equity Tier 1 capital and Additional Tier 1 capital. Common Equity Tier 1 capital generally consists of common stock, capital surplus, retained earnings, accumulated other comprehensive income and other disclosed reserves and others less any regulatory adjustments. Additional Tier 1 capital generally consists of instruments issued by a bank or its holding company that meet the criteria for inclusion in Additional Tier 1 capital and others less any regulatory adjustments. Tier 2 capital generally consists of instruments issued by a bank or its holding company such as subordinated debt that meet the criteria for inclusion in Tier 2 capital, general reserve for possible losses on loans (equaling the sum of (i) the excess of the amount of qualified reserves over the amount of expected losses and (ii) the amount of general reserves calculated based on the standardized approach) and others less any regulatory adjustments. 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 preferred securities (the amounts thereof included within Additional Tier 1 capital as of March 31, 2017 being ¥577.5 billion) and existing subordinated debt issued before March 2013 (the amounts thereof included within Tier 2 capital as of March 31, 2017 being ¥842.1 billion) are subject to the phase-out In November 2011, the Financial Stability Board (“FSB”) published policy measures to address the systemic and moral hazard risks associated with systemically important financial institutions. The policy measures include requirements for global systemically important banks (“G-SIBs”) G-SIBs In November 2015, the Financial Service Agency published the revised capital adequacy guidelines to introduce the Basel III rules text regarding the capital conservation buffer, the countercyclical capital buffer and the additional loss absorption capacity requirement for G-SIBs and domestic systemically important banks (“D-SIBs”). G-SIBs D-SIBs build-up In December 2015, the Financial Service Agency published a capital adequacy guideline regarding the designation of G-SIBs D-SIBs (“G-SIB”) (“D-SIB”), Regulatory adjustments such as goodwill and other intangibles, and defined benefit pension fund assets and liabilities, are to be applied mainly to the calculation of Common Equity Tier 1 capital in the form of the deductions. The regulatory adjustments began at 20% of the required deductions in the calculation of Common Equity Tier 1 capital in March 2014 and will be increased by 20% increments per year through March 2018 when the regulatory adjustments reach 100%. During this transition period, the remainder not deducted from capital will continue to be subject to existing national treatments. 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 2016 March 2017 March 2018 March 2019 March 2020 March 2021 March 2022 Minimum Common Equity Tier 1 capital 4.5 % 4.5 % 4.5 % 4.5 % 4.5 % 4.5 % 4.5 % Minimum Tier 1 capital 6.0 % 6.0 % 6.0 % 6.0 % 6.0 % 6.0 % 6.0 % Minimum total capital 8.0 % 8.0 % 8.0 % 8.0 % 8.0 % 8.0 % 8.0 % Capital conservation buffer 0.625 % 1.25 % 1.875 % 2.5 % 2.5 % 2.5 % 2.5 % Phase out of recognition of capital instruments that no longer qualify as capital 60.0 % 50.0 % 40.0 % 30.0 % 20.0 % 10.0 % 0.0 % Phase-in 60.0 % 80.0 % 100.0 % 100.0 % 100.0 % 100.0 % 100.0 % Additional loss absorbency requirements for G-SIBs D-SIBs (Note) 0.25 % 0.50 % 0.75 % 1.0 % 1.0 % 1.0 % 1.0 % Note: Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB D-SIB If the capital adequacy ratio of a financial institution falls below the required level, the Financial Services Agency may, depending upon the extent of capital deterioration, take certain corrective action, including requiring the financial institution to submit an improvement plan to strengthen its capital base, reduce 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 of MHFG, MHBK, and MHTB as of March 31, 2016 and 2017 calculated in accordance with Japanese GAAP and the guidelines established by the Financial Services Agency are set forth in the following table: 2016 2017 Amount Ratio Amount Ratio (in billions of yen, except percentages) Consolidated: MHFG: Common Equity Tier 1 capital: Required (Note) 3,361 5.375 3,857 6.25 Actual 6,566 10.50 7,002 11.34 Tier 1 capital: Required (Note) 4,299 6.875 4,783 7.75 Actual 7,905 12.64 8,212 13.30 Total risk-based capital: Required (Note) 5,550 8.875 6,017 9.75 Actual 9,639 15.41 10,051 16.28 MHBK: Common Equity Tier 1 capital: Required 2,555 4.50 2,541 4.50 Actual 6,142 10.81 6,304 11.16 Tier 1 capital: Required 3,406 6.00 3,388 6.00 Actual 7,244 12.75 7,536 13.34 Total risk-based capital: Required 4,542 8.00 4,517 8.00 Actual 8,780 15.46 9,149 16.20 MHTB: Common Equity Tier 1 capital: Required 109 4.50 112 4.50 Actual 440 18.21 466 18.73 Tier 1 capital: Required 145 6.00 149 6.00 Actual 440 18.21 466 18.73 Total risk-based capital: Required 193 8.00 199 8.00 Actual 472 19.52 485 19.47 Non-consolidated: MHBK: Common Equity Tier 1 capital: Required 2,489 4.50 2,432 4.50 Actual 5,892 10.65 6,057 11.20 Tier 1 capital: Required 3,318 6.00 3,243 6.00 Actual 7,004 12.66 7,316 13.53 Total risk-based capital: Required 4,424 8.00 4,324 8.00 Actual 8,576 15.50 8,938 16.53 MHTB: Common Equity Tier 1 capital: Required 109 4.50 113 4.50 Actual 448 18.52 475 18.98 Tier 1 capital: Required 145 6.00 150 6.00 Actual 448 18.52 475 18.98 Total risk-based capital: Required 194 8.00 200 8.00 Actual 480 19.80 493 19.70 Note: The required ratios disclosed above, at March 31, 2016 and 2017, include the transitional capital conservation buffer of 0.625% and 1.25%, respectively, and the transitional additional loss absorbency requirements for G-SIBs D-SIBs MHFG’s securities subsidiaries in Japan are also subject to the capital adequacy requirement under the 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 determined in accordance with Japanese GAAP, 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 March 31, 2017, that MHFG, MHBK, MHTB, and their securities subsidiaries in Japan 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, 2017
Earnings per common share	19. 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 the assumed conversion to common shares of all convertible securities such as convertible preferred stock. The following table sets forth the computation of basic and diluted earnings per common share for the fiscal years ended March 31, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Net income: Net income attributable to MHFG shareholders 803,048 850,492 362,440 Less: Net income attributable to preferred shareholders 4,910 2,430 — Net income attributable to common shareholders 798,138 848,062 362,440 Effect of dilutive securities: Convertible preferred stock 4,910 2,430 — Net income attributable to common shareholders after assumed conversions 803,048 850,492 362,440 2015 2016 2017 (thousands of shares) Shares: Weighted average common shares outstanding 24,368,116 24,806,161 25,285,899 Effect of dilutive securities: Convertible preferred stock (Note) 994,745 563,044 82,993 Stock options 18,186 17,828 11,410 Weighted average common shares after assumed conversions 25,381,047 25,387,033 25,380,302 2015 2016 2017 (in yen) Amounts per common share: Basic net income per common share 32.75 34.19 14.33 Diluted net income per common share 31.64 33.50 14.28 Note: The number of common shares after assumed conversion of the convertible preferred stock is based on the applicable conversion prices.

Income taxes

Income taxes	12 Months Ended
	Mar. 31, 2017
Income taxes	20. Income taxes Income tax expense The following table presents the components of Income tax expense for the fiscal years ended March 31, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Current: Domestic 184,180 162,408 130,164 Foreign 71,250 61,009 68,512 Total current tax expense 255,430 223,417 198,676 Deferred: Domestic 187,134 127,185 (99,831 ) Foreign (5,144 ) (4,060 ) (7,601 ) Total deferred tax expense 181,990 123,125 (107,432 ) Total income tax expense 437,420 346,542 91,244 The preceding table does not reflect the tax effects of items recorded directly in Equity for the fiscal years ended March 31, 2015, 2016 and 2017. The detailed amounts recorded directly in Equity are as follows: 2015 2016 2017 (in millions of yen) Net unrealized gains (losses) on available-for-sale Unrealized gains (losses) 403,690 (97,339 ) 112,467 Less: reclassification adjustments (65,699 ) (65,207 ) (97,729 ) Total 337,991 (162,546 ) 14,738 Foreign currency translation adjustments: Unrealized gains (losses) — 126 — Less: reclassification adjustments — — — Total — 126 — Pension liability adjustments: Unrealized gains (losses) 87,654 (51,661 ) 4,785 Less: reclassification adjustments (16 ) (1,317 ) 178 Total 87,638 (52,978 ) 4,963 Total tax effect before allocation to noncontrolling interests 425,629 (215,398 ) 19,701 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, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen, except tax rates) Income before income tax expense 1,267,653 1,196,605 480,375 Effective statutory tax rate 35.64 % 33.06 % 30.86 % Income tax calculated at the statutory tax rate 451,792 395,598 148,244 Income not subject to tax (20,911 ) (12,888 ) (7,521 ) Expenses not deductible for tax purposes 1,532 1,521 1,483 Tax rate differentials of subsidiaries (3,517 ) (2,208 ) (2,165 ) Change in valuation allowance (4,444 ) (1,897 ) 112,781 (3) Change in undistributed earnings of subsidiaries 16,084 (16,112 ) 5,217 Change in net operating loss carryforwards resulting from intercompany capital transactions (1,290 ) (1,446 ) 647 Effect of enacted change in tax rates (21,714 ) (1) (7,976 ) (2) — Reversal of outside basis differences — — (159,119 ) (3) Other 19,888 (8,050 ) (8,323 ) Income tax expense 437,420 346,542 91,244 Notes: (1) On March 31, 2015, the National Diet of Japan approved a bill affecting the statutory tax rates of MHFG and its domestic subsidiaries. As a result, the statutory tax rate in respect of MHFG’s tax returns for the fiscal year ended March 31, 2016 was reduced to 33.06% from the previous rate of 35.64%. In addition, the tax rate for the fiscal years ended March 31, 2017 and thereafter was reduced to 32.26%. The decrease in the MHFG Group’s balance of net deferred tax liabilities, reflecting such tax rate reductions, was recognized as a reduction to Income tax expense in the fiscal year ended March 31, 2015. (2) On March 29, 2016, the National Diet of Japan approved a bill affecting the statutory tax rates of MHFG and its domestic subsidiaries. As a result, the statutory tax rate in respect of MHFG’s tax returns for the fiscal year ended March 31, 2017 was reduced to 30.86% from the previous rate of 32.26%, and the statutory tax rate for the fiscal year ending March 31, 2018 will be the same rate. In addition, the tax rate for the fiscal years ending March 31, 2019 and thereafter will be 30.62%. The decrease in the Group’s balance of net deferred tax liabilities, reflecting such tax rate reductions, was recognized as a reduction to Income tax expense in the fiscal year ended March 31, 2016. (3) These amounts for the fiscal year ended March 31, 2017 represent mainly the reversal of an outside basis difference related to certain foreign subsidiaries due to their organizational restructuring and the related increase in the valuation allowance. Deferred tax assets and liabilities The components of net deferred tax assets (liabilities) at March 31, 2016 and 2017 are as follows: 2016 2017 (in millions of yen) Deferred tax assets: Investments 522,197 497,629 Allowance for loan losses 178,683 184,366 Trading securities — 30,841 Derivative financial instruments — 14,537 Premises and equipment — 3,594 Net operating loss carryforwards (1) (2) 341,572 452,166 Other 170,414 190,083 1,212,866 1,373,216 Valuation allowance (2) (339,922 ) (438,344 ) Deferred tax assets, net of valuation allowance 872,944 934,872 Deferred tax liabilities: Available-for-sale 710,497 724,160 Prepaid pension cost and accrued pension liabilities 174,959 195,620 Undistributed earnings of subsidiaries 11,944 17,161 Derivative financial instruments 56,877 — Trading securities 23,154 — Premises and equipment 1,033 — Other 38,990 74,886 Deferred tax liabilities 1,017,454 1,011,827 Net deferred tax assets (liabilities) (144,510 ) (76,955 ) Notes: (1) The amount includes ¥268,544 million and ¥271,266 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions as of March 31, 2016 and 2017, respectively. The tax effect of the net operating loss carryforwards is offset by a full valuation allowance because MHFG experienced a significant expiration of net operating loss carryforwards of ¥1,262 billion in March 2013, which is negative evidence outweighing any positive evidence. Furthermore, MHFG is a holding company whose primary sources of future taxable income are management fees from subsidiaries that are not sufficient to realize deferred tax assets related to the net operating loss carryforwards. (2) The amount includes ¥115,698 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2017. The tax effect of the net operating loss carryforwards is substantially offset by ¥90,204 million 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. 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, 2016 and 2017: Deferred tax assets Valuation allowance Deferred tax assets, net of valuation allowance (in billions of yen) 2016 Japan (1) 270 (270 ) — The United States 16 (8 ) 8 The United Kingdom (2) 53 (53 ) — Others 3 (3 ) — Total 342 (334 ) 8 2017 Japan (3) 388 (362 ) 26 The United States 15 (3 ) 12 The United Kingdom (2) 46 (46 ) — Others 3 (3 ) — Total 452 (414 ) 38 Notes: (1) ¥265 billion of the Japan deferred tax assets of ¥270 billion is related to MHFG, which is offset by a full valuation allowance, and will expire during the fiscal year ending March 31, 2018. (2) The United Kingdom net operating loss carryforwards may be carried forward indefinitely for the tax purposes. (3) ¥265 billion of the Japan deferred tax assets of ¥388 billion is related to MHFG, which is offset by a full valuation allowance, and will expire during the fiscal year ending March 31, 2018. In addition, ¥116 billion of the Japan deferred tax assets 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 non-principal 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, 2017, 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, 2017. 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, 2017, 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, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Balance at beginning of fiscal year 443,847 388,551 339,922 Changes that directly affected Income tax expense (4,444 ) (1,897 ) 112,781 Changes that did not affect Income tax expense: Expiration of net operating loss carryforwards — — — Others (50,852 ) (46,732 ) (14,359 ) Total (50,852 ) (46,732 ) (14,359 ) Balance at end of fiscal year 388,551 339,922 438,344 The decrease in the fiscal year ended March 31, 2015 of ¥4,444 million in the valuation allowance that directly affected Income tax expense was a result of an assessment of the realizability of deferred tax assets that mainly reflected decreases in deductible temporary differences. The decrease in the fiscal year ended March 31, 2015 of ¥50,852 million in others was primarily related to a decrease in the valuation allowance that is fully recognized against MHFG’s net operating loss carryforwards due to tax rate reductions. The decrease in the fiscal year ended March 31, 2016 of ¥1,897 million 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 decrease in the fiscal year ended March 31, 2016 of ¥46,732 million in others was primarily related to a decrease in the valuation allowance that is fully recognized against the MHFG Group’s net operating loss carryforwards due to tax rate reductions and the anticipated liquidation of one of MHFG’s subsidiaries. The increase in the fiscal year ended March 31, 2017 of ¥112,781 million in the valuation allowance that directly affected Income tax expense was a result of an assessment of realizability of deferred tax assets related to the net operating loss carryforwards, primarily related to the reversal of an outside basis difference related to certain foreign subsidiaries due to their organizational restructuring. The decrease in the fiscal year ended March 31, 2017 of ¥14,359 million in others was primarily related to a decrease in the valuation allowance that is fully recognized against the MHFG Group’s net operating loss carryforwards due to tax rate reductions and foreign currency rate reductions of MHFG’s foreign subsidiaries. Net operating loss carryforwards At March 31, 2017, the MHFG Group had net operating loss carryforwards totaling ¥1,590 billion. These carryforwards are scheduled to expire as follows: Net operating loss (in billions of yen) Fiscal year ending March 31: 2018 865 2019 4 2020 — 2021 — 2022 1 2023 and thereafter (Note) 720 Total 1,590 Note: Including the net operating loss carryforwards which may be carried forward indefinitely in the United Kingdom. Included in net operating loss carryforwards in the above table are MHFG’s net operating loss carryforwards of ¥879 billion resulting mainly from intercompany capital transactions, ¥865 billion of which are net operating loss carryforwards generated in relation to a previous intragroup reorganization. The tax loss was recorded at MHFG in accordance with Japanese tax law. The net operating loss carryforwards due to this transaction are to expire in March 31, 2018. In addition, included in the net operating loss carryforwards in the above table are MHSC’s net operating loss carryforwards of ¥378 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 are to expire in 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, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Total unrecognized tax benefits at beginning of fiscal year 1,691 1,632 1,300 Gross amount of increases (decreases) related to positions taken during prior years (37 ) (415 ) 167 Gross amount of increases related to positions taken during the current year 346 181 409 Amount of decreases related to settlements (652 ) — — Foreign exchange translation 284 (98 ) (9 ) Total unrecognized tax benefits at end of fiscal year 1,632 1,300 1,867 The total amount of unrecognized tax benefits including ¥517 million, ¥506 million and ¥675 million of interest and penalties was ¥1,632 million, ¥1,300 million and ¥1,867 million at March 31, 2015, 2016 and 2017, 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 2008, 2002 and 2015, respectively. The Group does not anticipate that increases or decreases of unrecognized tax benefits within the next twelve months would have a material effect on its consolidated results of operations or financial condition.

Pension and other employee bene

Pension and other employee benefit plans	12 Months Ended
	Mar. 31, 2017
Pension and other employee benefit plans	21. 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. 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, 2015, 2016 and 2017 were ¥2,444 million, ¥2,820 million and ¥3,141 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, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Service cost-benefits earned during the fiscal year 33,578 38,032 44,367 Interest costs on projected benefit obligations 13,060 10,479 5,724 Expected return on plan assets (38,087 ) (40,603 ) (35,969 ) Amortization of prior service benefits (195 ) (195 ) (195 ) Amortization of net actuarial loss (gain) 150 (4,108 ) 780 Special termination benefits 5,504 4,456 3,857 Net periodic benefit cost 14,010 8,061 18,564 Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before-tax 2016 2017 (in millions of yen) Net actuarial gain (loss) (160,132 ) 15,645 Amortization of net actuarial loss (gain) (4,108 ) 780 Amortization of prior service benefits (195 ) (195 ) Total recognized in other comprehensive income (loss) before-tax (164,435 ) 16,230 As of March 31, 2017, 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 ¥180 million and ¥417 million, respectively. Weighted-average assumptions used to determine benefit obligations and net periodic benefit cost are as follows: 2015 2016 2017 Weighted-average assumptions used to determine benefit obligations at fiscal year end: Discount rates 0.76 % 0.37 % 0.47 % Rates of increase in future compensation levels 2.00-4.80 % 1.80-4.80 % 1.80-4.80 % Weighted-average assumptions used to determine net periodic benefit cost during the year: Discount rates 0.96 % 0.76 % 0.37 % Rates of increase in future compensation levels 2.00-4.80 % 2.00-4.80 % 1.80-4.80 % Expected rates of return on plan assets 2.17 % 1.95 % 1.73 % In estimating the discount rates, the MHFG Group uses interest rates on high-quality fixed-income government and corporate bonds. The durations of such 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 environment. The following table sets forth the combined funded status and amounts recognized in the accompanying consolidated balance sheets at March 31, 2016 and 2017 for the plans of MHFG and its subsidiaries: 2016 2017 (in millions of yen) Change in benefit obligations: Benefit obligations at beginning of fiscal year 1,392,459 1,495,208 Service cost 38,032 44,367 Interest cost 10,479 5,724 Plan participants’ contributions 1,192 1,215 Actuarial loss (gain) 125,122 67,335 Foreign exchange translation (4,054 ) (2,159 ) Benefits paid (51,392 ) (51,899 ) Lump-sum (16,630 ) (13,898 ) Benefit obligations at end of fiscal year 1,495,208 1,545,893 Change in plan assets: Fair value of plan assets at beginning of fiscal year 2,081,600 2,082,996 Actual return (negative return) on plan assets 5,058 118,714 Foreign exchange translation (3,312 ) (3,273 ) Employer contributions 49,850 53,059 Plan participants’ contributions 1,192 1,215 Benefits paid (51,392 ) (51,899 ) Fair value of plan assets at end of fiscal year 2,082,996 2,200,812 Funded status 587,788 654,919 Amounts recognized in the consolidated balance sheets consist of: Prepaid pension cost 612,102 682,592 Accrued pension liability (24,314 ) (27,673 ) Net amount recognized 587,788 654,919 Amounts recognized in Accumulated other comprehensive income (loss) before-tax Prior service benefits (cost) (1,025 ) (1,220 ) Net actuarial gain (loss) 57,619 74,044 Net amount recognized 56,594 72,824 Note: The aggregated accumulated benefit obligations of these plans were ¥1,493,393 million and ¥1,544,039 million, as of March 31, 2016 and 2017, respectively. The defined benefit plans generally employ a multi-variable and non-linear lump-sum In the fiscal year ended March 31, 2017, the Group incorporated employee-level anticipated future mortality improvement actuarial indicators in its pension benefit calculation, which resulted in an increase of the benefit obligations of ¥79,861 million. 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, 2016 and 2017: 2016 2017 (in millions of yen) Plans with projected benefit obligations in excess of plan assets: Projected benefit obligations 50,554 57,980 Fair value of plan assets 26,240 30,306 Plans with accumulated benefit obligations in excess of plan assets: Accumulated benefit obligations 48,738 56,125 Fair value of plan assets 26,240 30,306 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 the 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, liquidity of a financial instrument, etc. The investments in each asset category are further diversified across funds, strategies, sectors, etc. 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, 2017 is as follows: Asset category Asset ratio Japanese equity securities 5.00 % Japanese debt securities 44.00 % Foreign equity securities 25.00 % Foreign debt securities 10.00 % General account of life insurance companies 14.00 % 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 rates. Fair value of plan assets The following table presents the fair value of plan assets of MHFG and its subsidiaries at March 31, 2016 and 2017, 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 28 “Fair value”. 2016 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in billions of yen) Japanese equity securities: Common stocks (1) 1,114 1 — 1,115 1,162 — — 1,162 Pooled funds (2) 10 1 — 11 10 — — 10 Japanese debt securities: Government bonds 262 — — 262 254 — — 254 Pooled funds (2) — 1 — 1 — 2 — 2 Other — 32 — 32 — 25 — 25 Foreign equity securities: Common stocks 98 — — 98 111 — — 111 Pooled funds (2) — 2 — 2 — 2 — 2 Foreign debt securities: Government bonds 72 2 — 74 68 3 — 71 Pooled funds (2) — 8 — 8 — 7 — 7 Other — 16 — 16 — 16 — 16 General account of life insurance companies (3) — 121 — 121 — 124 — 124 Hedge funds — — — — — — — — Other 44 (4) (4 ) (5) — 40 78 1 — 79 Plan assets measured at net asset value (6) 303 338 Total assets at fair value 1,600 180 — 2,083 1,683 180 — 2,201 Notes: (1) This class represents equity securities held in the employee retirement benefit trusts of ¥1,115 billion and ¥1,162 billion at March 31, 2016 and 2017, 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. (4) Amounts primarily include cash and short-term assets carried at fair value. (5) Amounts primarily include foreign exchange contracts carried at fair value. (6) 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. Amounts of actual returns on and purchases and sales of Level 3 assets during the fiscal years ended March 31, 2016 and 2017 were not significant. Contributions The total contribution of approximately ¥51 billion is expected to be paid to the pension plans during the fiscal year ending March 31, 2018, 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: 2018 66,140 2019 67,758 2020 69,578 2021 70,808 2022 71,549 2023-2027 354,180

Stock-based compensation

Stock-based compensation	12 Months Ended
	Mar. 31, 2017
Stock-based compensation	22. 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 amount to be paid upon exercise shall be 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, 2017: Number of Weighted-average Weighted-average Aggregate (in yen) (in years) (in millions of yen) Outstanding at beginning of fiscal year 17,190,000 1 Exercised during fiscal year 6,371,000 1 Outstanding at end of fiscal year 10,819,000 1 16.49 2,196 Exercisable at end of fiscal year — — — — There were no non-vested The following table presents the assumptions used in the Black-Scholes option pricing model to estimate the fair value of the stock acquisition rights granted during the fiscal year ended March 31, 2015. The risk-free interest rate is based on the Japanese government bonds yield curve for the expected remaining term in effect at the date of grant. The expected volatility is based on the historical trading data of MHFG common stock. The expected remaining term is based on the average service period of Directors of MHFG, MHBK, MHTB and MHSC, which represents the period of time that stock acquisition rights granted are expected to be outstanding. The expected dividend yield is based on the dividend rate of MHFG common stock at the date of grant. 2015 Risk-free interest rate 0.01 % Expected volatility 25.91 % Expected remaining term (in years) 2.46 Expected dividend yield 3.42 % The weighted-average grant-date fair value of stock acquisition rights granted during the fiscal year ended March 31, 2015 was ¥186,990. The compensation cost related to this plan recognized in income was ¥1,795 million during the fiscal year ended March 31, 2015. In May, 2015, MHFG announced discontinuance of the current stock option program along with the introduction of performance payments and performance-based stock compensation for Directors. Thereafter, MHFG has not issued and will not issue any new stock options. Performance-based stock compensation MHFG, MHBK, MHTB and MHSC introduced a new performance-based stock compensation program for Directors on May, 2015 using a trust. The program utilizes the Board Benefit Trust framework. The performance-based 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 officers’ interests with those of the shareholders and increasing the incentive to enhance corporate value. The payment thereof is a reflection of each officer’s performance. The entire amount of the payment in respect of the performance-based stock compensation is deferred over three years and the deferred portion is subject to reduction or forfeiture depending on certain factors, including the performance of the MHFG group or the relevant Directors. The following table presents activities related to the performance-based stock compensation for the fiscal year ended March 31, 2017: Number of shares Weighted-average grant-date fair value (per share in yen) Outstanding as of March 31, 2016 — — Granted during fiscal year 9,000,000 158.68 Vested during fiscal year — — Forfeited during fiscal year — — Outstanding as of March 31, 2017 9,000,000 158.68 The shares of MHFG common stock were acquired from the stock market by the trustee by using the money entrusted to the Compensation Committee. The total amount of the common stock was ¥1,428 million. The compensation cost with regard to the performance-based stock compensation is determined based upon the fair value of shares of MHFG common stock as of grant date and is recognized over three year deferral period on a straight-line basis. The compensation cost recognized in this performance-based stock compensation program for the fiscal year ended March 31, 2017 was ¥354 million. As of the fiscal year ended March 31, 2017, the total compensation cost related to non-vested

Derivative financial instrument

Derivative financial instruments	12 Months Ended
	Mar. 31, 2017
Derivative financial instruments	23. Derivative financial instruments The MHFG Group enters into derivative financial instruments in response to the diverse needs of customers, to control 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. 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 credit risk is measured by the fair value of all derivatives in a gain position and its potential increase at the balance sheet dates. The exposure to 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, 2016 and 2017. The fair values of 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 master netting agreements in the consolidated balance sheets, or the table below. Fair value Derivative receivables (2) Derivative payables (2) 2016 Notional amount (1) Designated Not designated Designated Not designated (in billions of yen) Interest rate contracts 1,066,252 — 11,522 — 11,269 Foreign exchange contracts 141,517 4 3,126 1 2,979 Equity-related contracts 3,115 18 152 — 140 Credit-related contracts 4,826 — 43 — 37 Other contracts 327 — 59 — 55 Total 1,216,037 22 14,902 1 14,480 Fair value Derivative receivables (2) Derivative payables (2) 2017 Notional amount (1) Designated Not designated Designated Not designated (in billions of yen) Interest rate contracts 961,518 — 8,506 — 8,473 Foreign exchange contracts 167,698 2 2,743 — 2,611 Equity-related contracts 4,177 — 134 5 224 Credit-related contracts 3,696 — 35 — 36 Other contracts 360 — 23 — 22 Total 1,137,449 2 11,441 5 11,366 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, not offset against derivative positions, was included in Other assets and Other liabilities, respectively, of which the amounts were ¥885 billion and ¥716 billion at March 31, 2016, and ¥973 billion and ¥672 billion at March 31, 2017, 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. Any ineffectiveness must be reported immediately in earnings. 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 available-for-sale The following table summarizes gains and losses information related to fair value hedges for the fiscal years ended March 31, 2015, 2016 and 2017: Gains (losses) recorded in income 2015 Derivatives Hedged Hedge Net gain (loss) excluded (in millions of yen) Equity-related contracts (29,666 ) 28,005 — (1,661 ) Total (29,666 ) 28,005 — (1,661 ) Gains (losses) recorded in income 2016 Derivatives Hedged Hedge Net gain (loss) excluded (in millions of yen) Equity-related contracts 14,623 (18,224 ) — (3,601 ) Total 14,623 (18,224 ) — (3,601 ) Gains (losses) recorded in income 2017 Derivatives Hedged Hedge Net gain (loss) excluded (in millions of yen) Equity-related contracts (14,747 ) 11,393 — (3,354 ) Total (14,747 ) 11,393 — (3,354 ) 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, 2015, 2016 and 2017: Gains (losses) recorded in income and other comprehensive income (“OCI”) 2015 2016 2017 Effective portion Ineffective portion Effective portion Ineffective portion Effective portion Ineffective portion (in millions of yen) Financial instruments hedging foreign exchange risk (53,252 ) (2,678 ) 46,697 696 16,767 47 Total (53,252 ) (2,678 ) 46,697 696 16,767 47 Note: No amount related to the effective portion of net investment hedges was reclassified from Accumulated other comprehensive income to earnings for the fiscal year ended March 31, 2015. Related to the effective portion of net investment hedges, gains of ¥345 million and ¥41 million were reclassified from Accumulated other comprehensive income to earnings for the fiscal years ended March 31, 2016 and 2017, respectively. 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 hedging strategies: (1) interest-rate swap transactions for the purpose of hedging the interest-rate risks in deposits, loans etc., (2) currency swap transactions for the purpose of hedging the foreign exchange risk of these assets, and (3) credit derivatives for the purpose of hedging the credit risk in loans, residential mortgage-backed securities (“RMBS”), commercial mortgage-backed securities (“CMBS”), 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 gain (loss) 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, 2015, 2016 and 2017: Gains (losses) recorded in income 2015 2016 2017 (in millions of yen) Interest rate contracts 265,324 319,225 (209,361 ) Foreign exchange contracts (93,601 ) 65,101 37,129 Equity-related contracts (1) (100,326 ) 21,571 5,131 Credit-related contracts (2) (18,007 ) (6,960 ) (6,694 ) Other contracts 368 2,015 742 Total 53,758 400,952 (173,053 ) Notes: (1) The net gain (loss) excluded from the assessment of the effectiveness of fair value hedges is not included in the above table. (2) Amounts include the net loss of ¥2,836 million, ¥5,230 million and ¥7,594 million on the credit derivatives hedging the credit risk of loans during the fiscal years ended March 31, 2015, 2016 and 2017, respectively. 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, 2016 and 2017: 2016 2017 Notional amount Fair value Notional amount Fair value (in billions of yen) Credit protection written: Investment grade 1,603 14 1,546 21 Non-investment 763 1 298 1 Total 2,366 15 1,844 22 Credit protection purchased 2,592 (9 ) 1,994 (23 ) 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, 2016 and 2017: Maximum payout/Notional amount 2016 2017 (in billions of yen) One year or less 538 507 After one year through five years 1,729 1,020 After five years 99 317 Total 2,366 1,844 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, 2016 and 2017: 2016 2017 (in billions of yen) Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions 790 698 Collateral provided to counterparties in the normal course of business 746 658 Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered 44 40

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Mar. 31, 2017
Commitments and contingencies	24. 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 with guarantees for the repayment of trust principal, e.g., loan trusts and certain jointly operated designated money trusts. Pursuant to Japanese trust-related laws, trustees are prohibited from compensating beneficiaries for any loss in the beneficial interests in each trust. However, under a special condition of the Japanese trust-related laws, trust banks as trustees are allowed to enter into an agreement to provide compensation for any loss in the principal of the trust. The MHFG Group manages and administers the 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. Carrying amount 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, 2016 and 2017 was ¥357 billion and ¥249 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 ¥336 billion and ¥228 billion at March 31, 2016 and 2017, respectively. Maximum exposure under guarantee contracts The table below summarizes the remaining term and maximum potential amount of future payments by type of guarantee at March 31, 2016 and 2017. The maximum potential amount of future payments disclosed below represents the contractual amounts that could be required to be repaid in the event of the guarantees being executed, without consideration of possible recoveries under recourse provisions or from collateral held. With respect to written options included in derivative financial instruments in the table below, in theory, the MHFG Group is exposed to unlimited losses; therefore, the table shows the notional amounts of the contracts as a substitute for the maximum exposure. 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 2016 Maximum Amount by expiration period One year or less After one year After five years (in billions of yen) Performance guarantees 2,110 1,049 909 152 Guarantees on loans 297 117 20 160 Guarantees on securities 203 67 136 — Other guarantees 1,571 1,206 325 40 Guarantees for the repayment of trust principal 1,141 1,051 63 27 Liabilities of trust accounts 12,747 12,537 79 131 Derivative financial instruments 15,792 6,505 8,032 1,255 2017 Maximum Amount by expiration period One year or less After one year After five years (in billions of yen) Performance guarantees 2,243 1,246 828 169 Guarantees on loans 278 147 20 111 Guarantees on securities 175 37 138 — Other guarantees 1,823 1,246 513 64 Guarantees for the repayment of trust principal 730 654 52 24 Liabilities of trust accounts 15,177 14,927 82 168 Derivative financial instruments 14,415 6,066 6,603 1,746 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, 2016 and 2017: 2016 2017 (in billions of yen) Investment grade 3,160 3,477 Non-investment 1,022 1,042 Total 4,182 4,519 Note: Investment grade in the internal rating scale generally corresponds to BBB- or above in the external rating scale. 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, 2016 and 2017: 2016 2017 (in billions of yen) Commitments to extend credit (Note) 75,742 76,678 Commercial letters of credit 448 522 Total 76,190 77,200 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 Leases The MHFG Group leases certain office space and equipment under noncancelable agreements. The lease periods for these leases range from less than 1 year to around 30 years. These leases include cancellation clauses with penalties of a maximum of approximately 5 years-worth of rentals and/or periodic adjustment clauses of rentals. The table below shows future minimum lease payments for capitalized leases and future minimum rental payments for operating leases at March 31, 2017: Capitalized leases Operating leases (in millions of yen) Fiscal year ending March 31: 2018 11,519 52,280 2019 10,721 46,330 2020 8,697 41,157 2021 6,118 35,291 2022 3,188 30,562 2023 and thereafter 1,846 57,787 Total minimum lease/rental payments 42,089 263,407 Amount representing interest 1,142 Present value of minimum lease payments 40,947 Total rental expense for the fiscal years ended March 31, 2015, 2016 and 2017 was ¥109,390 million, ¥118,400 million and ¥113,991 million, respectively. During prior years, the MHFG Group’s major banking subsidiaries sold their head offices (including land, buildings, facilities and equipment) to third parties. Concurrent with the sales, these subsidiaries leased the properties back for periods of 5 and 10 years for total rental payments for these periods of ¥214,690 million. The terms of certain lease agreements were changed during the fiscal years ended March 31, 2009, 2011, 2012 and 2014, and the total rental payments for these periods increased to ¥282,832 million, as a consequence. The MHFG Group accounted for the transactions as operating leases. The future minimum rental payments under the terms of the related lease agreements were ¥58,336 million, ¥49,883 million and ¥41,430 million at March 31, 2015, 2016 and 2017, respectively. During the fiscal year ended March 31, 2014, MHFG began to lease its head office from a third party and accounted for the lease arrangement as operating lease. Legal proceedings The MHFG Group is involved in normal collection proceedings initiated by the Group and other legal proceedings in the ordinary course of business. The Group’s Indonesian subsidiary acts as the collateral agent for the trustee of bond issuances made by subsidiaries of Asia Pulp & Paper Company Ltd. (“APP”). In that role, the subsidiary is involved in a dispute between the bondholders and such APP subsidiaries in their capacities as the issuers, guarantors and/or pledgors of security for the bonds relating to foreclosure proceedings in respect of the collateral and the subsidiary has been named as a defendant in a lawsuit brought by the obligors under the bonds in Indonesia. The Group’s consolidated financial statements do not include a reserve in relation to this dispute and the Group does not believe that the resolution of this matter will have a significant impact on the consolidated financial condition or results of operations of the Group, although there can be no assurance as to the foregoing.

Variable interest entities and

Variable interest entities and securitizations	12 Months Ended
	Mar. 31, 2017
Variable interest entities and securitizations	25. 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, and structured finance. 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 comprehensively 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, as of March 31, 2016 and 2017: Consolidated VIEs Significant 2016 Consolidated assets Total assets Maximum (in billions of yen) Asset-backed commercial paper/loan programs 2,092 — — Asset-backed securitizations 579 205 13 Investments in securitization products 337 445 154 Investment funds 1,660 2,422 367 Trust arrangements and other 24 — — Total 4,692 3,072 534 Consolidated VIEs Significant 2017 Consolidated assets Total assets Maximum (in billions of yen) Asset-backed commercial paper/loan programs 2,031 — — Asset-backed securitizations 629 108 11 Investments in securitization products 375 445 154 Investment funds 2,188 3,895 463 Trust arrangements and other 23 — — Total 5,246 4,448 628 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, 2016 and 2017: Assets on balance sheets related to unconsolidated VIEs: 2016 2017 (in billions of yen) Trading account assets 55 85 Investments 254 254 Loans 205 237 Total 514 576 Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs: 2016 2017 (in billions of yen) Payables under securities lending transactions 27 31 Trading account liabilities 1 1 Total 28 32 Maximum exposure to loss (Note) 534 628 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 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 to meet its clients’ needs for off-balance-sheet 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 certain VIEs, where the MHFG Group provides liquidity and credit support facilities, writes credit protection or invests in debt or equity instruments in its role as an arranger, servicer, administrator or asset manager, etc., the Group has the power to determine which assets will be held by the VIEs or to manage and monitor these assets. In addition, through the variable interests above, the Group has the obligation to absorb losses and the right to receive benefits that could potentially be significant to the VIEs. Therefore, the Group consolidates such VIEs. 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. 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 to be VIEs. By design, such investments were investment grade at issuance and held by a diverse group of investors. The potential loss amounts of the securities and the loans are generally limited to the amounts invested because the Group has no contractual involvement in such VIEs beyond its investments. Since the Group is involved in these VIEs only as an investor, the Group does not ordinarily have the power to direct the VIEs’ activities that most significantly impact the VIEs’ economic performance. However, the Group consolidates VIEs, where the transactions are tailored by the third party arrangers to meet the Group’s needs as a main investor, who is ultimately deemed to have the power to determine which assets are to be held by the VIEs. The Group also invests in certain beneficial interests issued by VIEs which hold real estate that the Group utilizes. In addition to these variable interests, when the Group has the power including the sole unilateral ability to liquidate the VIEs, the Group consolidates such VIEs. 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 consolidates certain investment funds where it is deemed to be the primary beneficiary. Prior to April 1, 2016, the Group determined that certain investment funds managed by the Group that had attributes of an investment company (or similar entity) qualified for the deferral from certain requirements of ASC 810 that originated from Statement of Financial Accounting Standards (“SFAS”) No.167 “Amendments to FASB Interpretation No.46(R)” (“SFAS No.167”). For these funds, the Group determined whether it was the primary beneficiary by evaluating whether it absorbed the majority of expected losses, received the majority of expected residual returns, or both. On April 1, 2016, the Group adopted ASU No.2015-02 Upon the adoption of ASU No.2015-02, 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. 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 (Refer to Note 11 “Due to trust accounts”). See Note 24 “Commitments and contingencies” for the balances of guaranteed trust principal that are not consolidated at March 31, 2016 and 2017. 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. 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. 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 860 are met. These criteria are (1) the transferred financial assets are legally isolated from the Group’s creditors, (2) the transferee or beneficial interest holder has the right to pledge or exchange the transferred financial assets, and (3) the Group does not maintain effective control over the transferred financial assets. If all the criteria are not met, the transfer is accounted for as a secured borrowing. For the fiscal years ended March 31, 2015, 2016 and 2017, 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, 2016 and 2017. 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 ¥243 billion and ¥64 billion as of March 31, 2016, and ¥244 billion and ¥91 billion as of March 31, 2017, 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.

Fee and commission income

Fee and commission income	12 Months Ended
	Mar. 31, 2017
Fee and commission income	26. Fee and commission income Details of Fee and commission income for the fiscal years ended March 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 (in millions of yen) Securities-related business 172,234 175,723 165,857 Deposits and lending business 131,491 143,763 164,573 Remittance business 110,181 109,859 108,368 Trust fees 49,827 50,496 47,379 Fees for other customer services 251,924 263,112 260,360 Total 715,657 742,953 746,537 Securities-related business fees consist of broker’s fees and markups on securities underwriting and other securities related activities. Remittance business fees consist of service charges for funds transfer and collections. Trust fees are earned primarily by fiduciary asset management and administration services for corporate pension plans, investment funds, and other. Fees for other customer services include fees related to the MHFG Group’s agency business, guarantee related business, and other. Fee and commission related to assets management business, which are included in Other noninterest income in the Group’s consolidated statement of income, for the fiscal years ended March 31, 2015, 2016 and 2017 were ¥57,998 million, ¥61,803 million and ¥79,426 million, respectively.

Trading account gains and losse

Trading account gains and losses	12 Months Ended
	Mar. 31, 2017
Trading account gains and losses	27. 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 available-for-sale 2015 2016 2017 (in millions of yen) Trading account gains (losses)—net: Trading securities 635,027 156,559 126,332 Derivative contracts: Interest rate contracts (1) 265,324 319,225 (209,361 ) Foreign exchange contracts (93,601 ) 65,101 37,129 Equity-related contracts (1) (101,988 ) 17,970 1,777 Credit-related contracts (2) (15,171 ) (1,731 ) 900 Other contracts 368 2,015 742 Total 689,959 559,139 (42,481 ) Foreign exchange gains (losses)—net (3) (34,520 ) 113,553 69,453 Net trading gains (losses) 655,439 672,692 26,972 Notes: (1) The net gain (loss) excluded from the assessment of the effectiveness of fair value hedges is included in the above table. (2) Amounts do not include the net loss of ¥2,836 million, ¥5,230 million and ¥7,594 million on the credit derivatives hedging the credit risk of loans during the fiscal years ended March 31, 2015, 2016 and 2017, respectively. The net loss is recorded in Other noninterest expenses. (3) Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments, such as translation gains and losses related to foreign currency-denominated available-for-sale

Fair value

Fair value	12 Months Ended
	Mar. 31, 2017
Fair value	28. 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 were previously applied to large holdings of publicly traded financial instruments. 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 well-documented 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 “ Investments” 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, 2017, 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 Ginnie Mae 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 foreign currency denominated securitization products such as RMBS, CMBS, and ABS 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. As it pertains to investment funds, exchange-traded funds (“ETF”) are generally classified in Level 1. Hedge funds the Group invests in are primarily multi strategy funds that employ a fundamental bottom-up start-up ten-year 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 Investments The fair values of available-for-sale non-binding Other investments, except for investments held by consolidated investment companies, have not been measured at fair value on a recurring basis. Investments held by consolidated investment companies mainly consist of marketable and non-marketable non-marketable Non-marketable Long-term debt Where fair value accounting has been elected for structured notes, the fair values are determined by incorporating the fair values of embedded derivatives that are primarily derived by using the same procedures described for derivative financial instruments above. Such instruments are classified in Level 2 or Level 3 depending on the observability of significant inputs to the model used in determining the fair value of the embedded derivatives. Items measured at fair value on a recurring basis Assets and liabilities measured at fair value on a recurring basis at March 31, 2016 and 2017, including those for which the MHFG Group has elected the fair value option, are summarized below: 2016 Level 1 Level 2 Level 3 Assets/ (in billions of yen) Assets: Trading securities (1) Japanese government bonds 2,272 31 — 2,303 Japanese local government bonds — 79 — 79 U.S. Treasury bonds and federal agency securities 3,729 77 — 3,806 Other foreign government bonds 2,192 373 — 2,565 Agency mortgage-backed securities 995 563 — 1,558 Residential mortgage-backed securities — — 21 21 Commercial mortgage-backed securities — 2 2 4 Certificates of deposit and commercial paper — 881 — 881 Corporate bonds and other 9 1,693 720 2,422 Equity securities 758 62 21 841 Trading securities measured at net asset value (2) 617 Derivatives: Interest rate contracts 97 11,396 29 11,522 Foreign exchange contracts 23 3,099 8 3,130 Equity-related contracts 46 95 29 170 Credit-related contracts — 40 3 43 Other contracts — 21 38 59 Available-for-sale Japanese government bonds 15,037 726 — 15,763 Japanese local government bonds — 241 — 241 U.S. Treasury bonds and federal agency securities 438 — — 438 Other foreign government bonds 352 590 — 942 Agency mortgage-backed securities 169 780 — 949 Residential mortgage-backed securities — 87 123 210 Commercial mortgage-backed securities — — 187 187 Japanese corporate bonds and other debt securities — 1,921 174 2,095 Foreign corporate bonds and other debt securities — 739 108 847 Equity securities (marketable) 3,716 65 — 3,781 Other investments — — 42 42 Total assets measured at fair value on a recurring basis 29,833 23,561 1,505 55,516 Liabilities: Trading securities sold, not yet purchased 2,482 148 — 2,630 Derivatives: Interest rate contracts 98 11,168 3 11,269 Foreign exchange contracts 26 2,953 1 2,980 Equity-related contracts 60 56 24 140 Credit-related contracts — 33 4 37 Other contracts — 18 37 55 Long-term debt (3) — 433 623 1,056 Total liabilities measured at fair value on a recurring basis 2,666 14,809 692 18,167 2017 Level 1 Level 2 Level 3 Assets/ (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,485 23 — 1,508 Japanese local government bonds — 69 — 69 U.S. Treasury bonds and federal agency securities 2,883 80 — 2,963 Other foreign government bonds 1,127 457 — 1,584 Agency mortgage-backed securities 1,335 638 — 1,973 Residential mortgage-backed securities — — 15 15 Commercial mortgage-backed securities — 3 — 3 Certificates of deposit and commercial paper — 554 — 554 Corporate bonds and other 3 1,449 1,052 2,504 Equity securities 1,661 20 23 1,704 Trading securities measured at net asset value (2) 678 Derivatives: Interest rate contracts 37 8,442 27 8,506 Foreign exchange contracts 28 2,709 8 2,745 Equity-related contracts 31 89 14 134 Credit-related contracts — 33 2 35 Other contracts 1 11 11 23 Available-for-sale Japanese government bonds 9,543 720 — 10,263 Japanese local government bonds — 284 — 284 U.S. Treasury bonds and federal agency securities 1,144 — — 1,144 Other foreign government bonds 346 589 — 935 Agency mortgage-backed securities 134 709 — 843 Residential mortgage-backed securities — 67 77 144 Commercial mortgage-backed securities — — 224 224 Japanese corporate bonds and other debt securities — 1,834 174 2,008 Foreign corporate bonds and other debt securities — 801 110 911 Equity securities (marketable) 3,717 84 — 3,801 Other investments — — 37 37 Total assets measured at fair value on a recurring basis 23,475 19,665 1,774 45,592 Liabilities: Trading securities sold, not yet purchased 1,993 228 — 2,221 Derivatives: Interest rate contracts 46 8,426 1 8,473 Foreign exchange contracts 20 2,591 — 2,611 Equity-related contracts 129 61 39 229 Credit-related contracts — 34 2 36 Other contracts 1 10 11 22 Long-term debt (3) — 903 593 1,496 Total liabilities measured at fair value on a recurring basis 2,189 12,253 646 15,088 Notes: (1) Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option. (2) 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, 2016 and 2017 were ¥30 billion and ¥33 billion, respectively. (3) Amounts represent items for which the Group elected the fair value option. 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, 2016 and 2017: 2016 April 1, Gains Gains Transfers Transfers Purchases Sales Issuances Settlements March 31, 2016 Change in (losses) (6) (in billions of yen) Assets: Trading securities: Other foreign government bonds — — (2) — — — 1 (1 ) — — — — Residential mortgage-backed securities 29 — (2) — — — — — — (8 ) 21 — Commercial mortgage-backed securities 4 — (2) — — — — — — (2 ) 2 — Corporate bonds and other 639 (43 ) (2) — 25 (34 ) 452 (192 ) — (127 ) 720 (38 ) Equity securities 23 (3 ) (2) — — — 1 — — — 21 (1 ) Derivatives, net (1) Interest rate contracts 18 (1 ) (2) — — — — — — 9 26 11 Foreign exchange contracts 8 (1 ) (2) — — — — — — — 7 (2 ) Equity-related contracts (14 ) 22 (2) — — — — — — (3 ) 5 14 Credit-related contracts (1 ) — (2) — — — — — — — (1 ) — Other contracts — 1 (2) — — — — — — — 1 1 Available-for-sale Residential mortgage-backed securities 166 — (3) — (4) — — — (4 ) — (39 ) 123 — Commercial mortgage-backed securities 169 — (3) — (4) — — 102 (62 ) — (22 ) 187 — Japanese corporate bonds and other debt securities 155 (2 ) (3) — (4) — — 67 (3 ) — (43 ) 174 (4 ) Foreign corporate bonds and other debt securities 85 2 (3) (5 ) (4) 23 — 41 — — (38 ) 108 — Other investments 53 7 (3) — — — 5 (20 ) — (3 ) 42 (7 ) Liabilities: Trading securities sold, not yet purchased — — (2) — — — (5 ) 5 — — — — Long-term debt 587 18 (5) — 8 — (1 ) — 305 (258 ) 623 19 2017 April 1, Gains Gains Transfers Transfers Purchases Sales Issuances Settlements March 31, 2017 Change in (losses) (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 21 (1 ) (2) — — — — — — (5 ) 15 (1 ) Commercial mortgage-backed securities 2 — (2) — — — — — — (2 ) — — Corporate bonds and other 720 12 (2) — 296 (39 ) 875 (555 ) — (257 ) 1,052 19 Equity securities 21 1 (2) — — — 3 (2 ) — — 23 — Derivatives, net (1) Interest rate contracts 26 (2 ) (2) — — — — — — 2 26 2 Foreign exchange contracts 7 7 (2) — — — — — — (6 ) 8 1 Equity-related contracts 5 (31 ) (2) — — — — — — 1 (25 ) (35 ) Credit-related contracts (1 ) 1 (2) — — — — — — — — — Other contracts 1 — (2) — — — — — — (1 ) — — Available-for-sale Residential mortgage-backed securities 123 — (3) (1 ) (4) — — — (7 ) — (38 ) 77 — Commercial mortgage-backed securities 187 — (3) 1 (4) — — 63 (12 ) — (15 ) 224 — Japanese corporate bonds and other debt securities 174 (1 ) (3) 43 (4) — — 10 (19 ) — (33 ) 174 — Foreign corporate bonds and other debt securities 108 1 (3) (1 ) (4) — (2 ) 10 — — (6 ) 110 — Other investments 42 — (3) — — — 12 (3 ) — (14 ) 37 — Liabilities: Trading securities sold, not yet purchased — — (2) — 1 — (54 ) 53 — — — — Long-term debt 623 20 (5) — 21 (12 ) (2 ) 1 278 (296 ) 593 18 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, 2016 and 2017. Transfers between levels 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, 2016, the transfers into Level 3 included ¥25 billion of Trading securities, ¥23 billion of Available-for-sale Available-for-sale During the fiscal year ended March 31, 2017, the transfers into Level 3 included ¥296 billion of Trading securities, ¥1 billion of Trading securities sold, not yet purchased and ¥21 billion of Long-term debt. Transfers into Level 3 for Trading securities and Trading securities sold, not yet purchased were primarily due to decreased liquidity for certain Japanese and foreign corporate bonds. Transfers into Level 3 for Long-term debt were primarily due to changes in the impact of unobservable inputs on the value of certain structured notes. During the fiscal year ended March 31, 2017, the transfers out of Level 3 included ¥39 billion of Trading securities, ¥2 billion of Available-for-sale Available-for-sale 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, 2016 and 2017: 2016 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 144 Discounted cash flow Prepayment rate 3%–19% 7% Price-based Default rate 0%–2% 0% Recovery rate 100%–100% 100% Discount margin 13bps–180bps 60bps Commercial mortgage-backed securities 189 Discounted cash flow Price-based Discount margin 6bps–580bps 37bps Corporate bonds and other debt securities 1,002 Discounted cash flow Prepayment rate (1) 0%–21% 19% Price-based Default rate (1) 0%–2% 2% Recovery rate (1) 60%–69% 68% Discount margin (1) 11bps–1,115bps 151bps Discount margin (2) 10bps–3,850bps 454bps Derivatives, net: Interest rate contracts 26 Internal valuation model (3) IR – IR correlation 32%–100% Default rate (4) 0%–63% Foreign exchange contracts 7 Internal valuation model (3) FX – IR correlation 5%–50% FX – FX correlation 54%–54% Default rate (4) 0%–63% Equity-related contracts 5 Internal valuation model (3) Equity – IR correlation 30%–30% Equity – FX correlation 55%–55% Equity volatility 10%–40% Credit-related contracts (1) Internal valuation model (3) Default rate 0%–42% Credit correlation 29%–100% Long-term debt 623 Internal valuation model (3) IR – IR correlation 32%–100% FX – IR correlation 5%–50% FX – FX correlation 54%–54% Equity – IR correlation 30%–30% Equity – FX correlation 55%–55% Equity correlation 18%–100% Equity volatility 14%–39% Default rate 0%–5% Credit correlation 28%–100% 2017 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 92 Discounted cash flow Prepayment rate 0%–18% 7% Price-based Default rate 0%–1% 0% Recovery rate 100%–100% 100% Discount margin 15bps–170bps 55bps Commercial mortgage-backed securities 224 Discounted cash flow Price-based Discount margin 4bps–205bps 28bps Corporate bonds and other debt securities 1,336 Discounted cash flow Prepayment rate (1) 16%–30% 29% Price-based Default rate (1) 1%–2% 2% Recovery rate (1) 60%–68% 68% Discount margin (1) 8bps–1,181bps 131bps Discount margin (2) 10bps–939bps 359bps Derivatives, net: Interest rate contracts 26 Internal valuation model (3) IR – IR correlation 23%–100% Default rate (4) 0%–63% Foreign exchange contracts 8 Internal valuation model (3) FX – IR correlation 5%–52% FX – FX correlation 55%–55% Default rate (4) 0%–63% Equity-related contracts (25) Internal valuation model (3) Equity – IR correlation 25%–25% Equity – FX correlation 55%–55% Equity volatility 6%–59% Credit-related contracts — Internal valuation model (3) Default rate 0%–5% Credit correlation 30%–100% Long-term debt 593 Internal valuation model (3) IR – IR correlation 23%–100% FX – IR correlation 5%–52% FX – FX correlation 55%–55% Equity – IR correlation 25%–25% Equity – FX correlation 55%–55% Equity correlation 20%–100% Equity volatility 5%–40% Default rate 0%–3% Credit correlation 33%–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, 2016 and 2017: 2016 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 124 — — 124 197 Loans held-for-sale 13 — 7 6 14 Other investments 1 — — 1 2 Premises and equipment—net — — — — 1 Goodwill — — — — 6 Total assets measured at fair value on a nonrecurring basis 138 — 7 131 220 2017 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 124 — — 124 194 Loans held-for-sale 7 — 7 — 8 Other investments 7 6 — 1 11 Premises and equipment—net 7 — 6 1 11 Total assets measured at fair value on a nonrecurring basis 145 6 13 126 224 Loans in the table above have been impaired and measured based upon the fair value of the underlying collateral. Loans held-for-sale Other investments in the table above, which consist of certain equity method investments and non-marketable non-marketable non-marketable non-marketable Premises and equipment—net in the table above have been impaired and written down to fair value. Goodwill in the table above is entirely related to Banco Mizuho do Brasil S.A. reporting unit. Due to the decline in the fair value of the reporting unit, the carrying amount of the goodwill was reduced to its fair value which is based on the market approach and an impairment loss was recognized. As the determination of the fair value of the goodwill required significant management judgment and estimation, it is classified as Level 3. Fair value option The MHFG Group elected the fair value option for certain eligible financial instruments described below. Foreign currency denominated available-for-sale Prior to the adoption of the fair value option in accordance with ASC 825, the changes in fair value of foreign currency denominated available-for-sale available-for-sale 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 ¥20 billion and ¥36 billion at March 31, 2016 and 2017, respectively. The net unrealized gains (losses) resulting from changes in fair values of these notes of ¥14 billion and ¥16 billion, which included the fair value changes attributable to changes in the Group’s own credit risk, were recorded in Other noninterest income (expenses) for the fiscal years ended March 31, 2016 and 2017, respectively. 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 fair value. Accordingly, the net realizable or liquidation values could be materially different from the estimates presented below. ASC 825 does not require the disclosure of the fair value of nonfinancial instruments. 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, 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 Performing loans have been fair valued as groups of similar loans based on the type of loan, credit quality, prepayment assumptions and remaining maturity. The fair value of performing 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 impaired loans is determined based on either discounted cash flows incorporating the Group’s best estimate of the expected future cash flows or the fair value of the underlying collateral, if impaired loans are collateral dependent. 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 13 “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 deposits and certificates of deposit is primarily estimated based on discounted cash flow analysis using current interest rates for instruments with similar maturities. The carrying value of short-term certificates of deposit approximates the fair value. Due to trust accounts The carrying value of due to trust accounts approximates the fair value since they generally have short-term maturities with interest rates that approximate market rates. Other short-term borrowings The carrying value of the majority of other short-term borrowings approximates the fair value since they generally have short-term maturities with interest rates that approximate market rates. The fair value of certain borrowings is estimated based on discounted cash flow analysis using interest rates approximating the MHFG Group’s incremental borrowing rates for instruments with similar maturities. Long-term debt Long-term debt is fair valued using quoted market prices, if available. Otherwise, the fair value of long-term debt is estimated based on discounted cash flow analysis using interest rates approximating the MHFG Group’s incremental borrowing rates for instruments with similar maturities. Other financial liabilities The carrying value of other financial liabilities, which primarily consist of accounts payable to brokers, dealers, and customers for securities transactions, accrued expenses and collateral accepted for derivative transactions, approximates the fair value since they generally have short-term maturities with interest rates that approximate market rates. The majority of other financial liabilities is classified as Level 2, and included in the table in Note 13 “Other assets and liabilities”. The fair value of certain off-balance-sheet The following table shows the carrying amounts and fair values at March 31, 2016 and 2017, 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

Offsetting of financial assets

Offsetting of financial assets and financial liabilities	12 Months Ended
	Mar. 31, 2017
Offsetting of financial assets and financial liabilities	29. 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, 2016 and 2017. 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 (3) Gross amounts recognized Gross amounts offset on the Net amounts presented on the (2) Financial instruments (4) Cash collateral Net (in billions of yen) 2016 Assets (1) Derivatives 14,130 — 14,130 (12,167 ) (599 ) 1,364 Receivables under resale agreements 7,490 — 7,490 (7,461 ) — 29 Receivables under securities borrowing transactions 3,327 — 3,327 (3,318 ) — 9 Total 24,947 — 24,947 (22,946 ) (599 ) 1,402 Liabilities (1) Derivatives 13,652 — 13,652 (12,043 ) (748 ) 861 Payables under repurchase agreements 16,507 — 16,507 (16,464 ) — 43 Payables under securities lending transactions 2,538 — 2,538 (2,531 ) — 7 Total 32,697 — 32,697 (31,038 ) (748 ) 911 2017 Assets (1) Derivatives 10,608 — 10,608 (8,966 ) (620 ) 1,022 Receivables under resale agreements 8,698 — 8,698 (8,662 ) — 36 Receivables under securities borrowing transactions 3,127 — 3,127 (3,116 ) — 11 Total 22,433 — 22,433 (20,744 ) (620 ) 1,069 Liabilities (1) Derivatives 10,405 — 10,405 (8,866 ) (901 ) 638 Payables under repurchase agreements 17,446 — 17,446 (17,391 ) — 55 Payables under securities lending transactions 1,458 — 1,458 (1,455 ) — 3 Total 29,309 — 29,309 (27,712 ) (901 ) 696 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, 2017
Repurchase agreements and securities lending transactions accounted for as secured borrowings	30. 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, 2016 and 2017: Overnight and Up to 30 days 31-90 days Greater than Total (in billions of yen) 2016 Repurchase agreements 6,289 6,125 3,582 837 16,833 Securities lending transactions 1,909 700 — 236 2,845 Total 8,198 6,825 3,582 1,073 19,678 2017 Repurchase agreements 249 12,700 3,897 1,124 17,970 Securities lending transactions 320 1,359 — 240 1,919 Total 569 14,059 3,897 1,364 19,889 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, 2016 and 2017: Repurchase Securities lending (in billions of yen) 2016 Japanese government bonds and Japanese local government bonds 532 1,891 Foreign government bonds and foreign agency mortgage-backed securities 15,781 700 Commercial paper and corporate bonds 221 27 Equity securities 141 185 Other 158 42 Total (Note) 16,833 2,845 2017 Japanese government bonds and Japanese local government bonds 1,127 1,152 Foreign government bonds and foreign agency mortgage-backed securities 15,782 375 Commercial paper and corporate bonds 294 47 Equity securities 578 320 Other 189 25 Total (Note) 17,970 1,919 Note: Amounts exceeded the gross amounts recognized in Note 29 “Offsetting of financial assets and financial liabilities” by ¥633 billion and ¥985 billion, at March 31, 2016 and 2017, 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 activities on a daily basis, diversifying the maturities and counterparties, and using mainly highly liquid securities.

Related party transactions

Related party transactions	12 Months Ended
	Mar. 31, 2017
Related party transactions	31. Related party transactions Transactions with directors, executive officers, and their associates The banking subsidiaries of MHFG make loans to the MHFG Group’s directors, executive officers, and their associates in their ordinary course of business. At March 31, 2016 and 2017, outstanding loans to such related parties were not considered significant. These related party loans were made on substantially the same terms, including interest rate and collateral, as those prevailing at the same time for comparable transactions with unrelated parties. At March 31, 2016 and 2017, there were no loans to these related parties that were considered impaired. Other transactions, such as deposits, were entered into between MHFG’s subsidiaries and the MHFG Group’s directors, executive officers, and their associates during the fiscal years ended March 31, 2015, 2016 and 2017. The outstanding amounts of these transactions, which were made in the ordinary course of business with substantially the same terms as those for comparable transactions with unrelated parties, were not considered significant. Transactions with other related parties A number of transactions were entered into with other related parties, such as MHFG’s employees and affiliates accounted for under the equity method. These transactions included loans, deposits, and other banking services. They were not significant in amount and were conducted with substantially the same terms as those for comparable transactions with unrelated parties.

Business segment information

Business segment information	12 Months Ended
	Mar. 31, 2017
Business segment information	32. Business segment information The MHFG Group has introduced an in-house Specifically, the company system is classified into the following five in-house In line with the aforementioned system, the reportable segments have been changed from those based on the relevant principal consolidated subsidiaries to the five in-house 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 each business segment’s net business profits with income before income tax expense under U.S. GAAP. Management does not use information on business segment’s assets to allocate resources and assess performance and has not prepared information on the segment’s assets. Accordingly, information on the segment’s assets is not available. MHFG (Consolidated) 2016 (1) Retail & Corporate & Global Global Asset Others (3) Total (in billions of yen) Gross profits 676.4 434.9 403.8 577.7 52.1 76.7 2,221.6 General and administrative expenses 661.2 183.2 232.7 178.9 30.1 58.9 1,345.0 Others — — — — — (23.7 ) (23.7 ) Net business profits (losses) (2) 15.2 251.7 171.1 398.8 22.0 (5.9 ) 852.9 MHFG (Consolidated) 2017 Retail & Corporate & Global Global Asset Others (3) Total (in billions of yen) Gross profits 646.1 445.1 386.5 539.4 49.6 26.0 2,092.7 General and administrative expenses 678.3 186.7 237.8 200.9 29.3 87.5 1,420.5 Others — — — — — (8.8 ) (8.8 ) Net business profits (losses) (2) (32.2 ) 258.4 148.7 338.5 20.3 (70.3 ) 663.4 Notes: (1) Following the introduction of an in-house (2) Net business profits is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (or the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income) less general and administrative expenses. Measurement of net business profits is required for regulatory reporting to the Financial Services Agency. (3) “Others” includes items which should be eliminated as internal transactions between each segment on a consolidated basis. Before the introduction of the in-house 2015 (1)(2) MHBK (Consolidated) MHTB (Consolidated) MHSC (Consolidated) Others MHFG MHBK (Non-consolidated) Others Total Total Personal Retail Banking Corporate (Large Corporate Financial Inter- national Trading and others (h) (i) (j) (k) Total (in billions of yen) Gross profits: Net interest income 1,087.3 934.9 213.4 77.6 179.5 99.6 33.3 147.1 184.4 152.4 39.4 1.8 0.9 1,129.4 Net noninterest income 598.4 560.6 48.7 53.7 128.0 79.8 27.4 164.9 58.1 37.8 122.6 335.8 61.5 1,118.3 Total 1,685.7 1,495.5 262.1 131.3 307.5 179.4 60.7 312.0 242.5 190.2 162.0 337.6 62.4 2,247.7 General and administrative expenses 904.7 833.7 233.5 118.4 94.4 76.5 30.3 92.6 188.0 71.0 94.5 268.0 54.0 1,321.2 Others (43.2 ) — — — — — — — — (43.2 ) (3.7 ) — (2.7 ) (49.6 ) Net business profits (3) 737.8 661.8 28.6 12.9 213.1 102.9 30.4 219.4 54.5 76.0 63.8 69.6 5.7 876.9 2016 (2) MHBK (Consolidated) MHTB (Consolidated) MHSC (Consolidated) Others MHFG (Consolidated) MHBK (Non-consolidated) Others Total Total Personal Retail Banking Corporate (Large Corporate Financial Inter- national Trading and others (h) (i) (j) (k) Total (in billions of yen) Gross profits: Net interest income 959.4 830.1 214.8 75.7 173.0 97.5 32.5 175.5 61.1 129.3 36.1 5.4 2.8 1,003.7 Net noninterest income 675.3 633.7 45.0 53.1 143.7 77.5 31.8 185.1 97.5 41.6 130.7 343.8 68.1 1,217.9 Total 1,634.7 1,463.8 259.8 128.8 316.7 175.0 64.3 360.6 158.6 170.9 166.8 349.2 70.9 2,221.6 General and administrative expenses 903.3 833.3 234.4 118.6 91.9 75.2 29.8 122.1 161.3 70.0 99.1 279.3 63.3 1,345.0 Others (22.1 ) — — — — — — — — (22.1 ) (4.2 ) — 2.5 (23.8 ) Net business profits (losses) (3) 709.3 630.5 25.4 10.2 224.8 99.8 34.5 238.5 (2.7 ) 78.8 63.5 69.9 10.1 852.8 2017 (2)(4) MHBK (Consolidated) MHTB (Consolidated) MHSC (Consolidated) Others MHFG (Consolidated) MHBK (Non-consolidated) Others Total (a)-(g) Total (h) (i) (j) (k) Total (in billions of yen) Gross profits: Net interest income (expense) 836.5 719.8 116.7 30.2 (1.5 ) 2.6 867.8 Net noninterest income 686.7 600.6 86.1 121.8 333.1 83.3 1,224.9 Total 1,523.2 1,320.4 202.8 152.0 331.6 85.9 2,092.7 General and administrative expenses 982.7 866.6 116.1 101.6 257.5 78.7 1,420.5 Others (8.7 ) — (8.7 ) (5.2 ) 0.1 5.0 (8.8 ) Net business profits (3) 531.8 453.8 78.0 45.2 74.2 12.2 663.4 Notes: (1) Beginning on April 1, 2015, new allocation methods have been applied to the calculation of “Gross profits” and “General and administrative expenses” for reportable segments of MHBK. Figures for the fiscal year ended March 31, 2015 have been restated for the new allocation methods. (2) “Others (h)” and “Others (k)” include the elimination of transactions between consolidated subsidiaries. (3) Net business profits is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (or the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income) less general and administrative expenses. Measurement of net business profits is required for regulatory reporting to the Financial Services Agency. (4) Segment information based on the relevant principal consolidated subsidiaries for the fiscal year ended March 31, 2017 is presented for comparability purposes. Due to system limitations, it is impracticable to present the details of MHBK (Non-consolidated). 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, to the corresponding items in the accompanying consolidated statements of income. A reconciliation of total net business profits under the internal management reporting systems for the fiscal years ended March 31, 2015, 2016 and 2017 presented above to income before income tax expense shown on the consolidated statements of income is as follows: 2015 2016 2017 (in billions of yen) Net business profits 876.9 852.8 663.4 U.S. GAAP adjustments 230.8 201.3 (387.8 ) (Provision) credit for loan losses 60.2 (34.6 ) (37.7 ) Net gains (losses) related to equity investments 160.1 188.4 259.6 Non-recurring (8.0 ) (3.9 ) (8.8 ) Gains on disposal of premises and equipment 2.8 10.2 5.6 (Provision) credit for losses on off-balance-sheet 2.8 16.4 (19.5 ) Others—net (57.9 ) (34.0 ) 5.6 Income before income tax expense 1,267.7 1,196.6 480.4

Foreign activities

Foreign activities	12 Months Ended
	Mar. 31, 2017
Foreign activities	33. 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 Others Europe Asia/Oceania and others Total (in billions of yen) Fiscal year ended March 31, 2015: Total revenue (1) 2,396.9 324.1 102.4 211.8 223.7 3,258.9 Total expenses (2) 1,459.9 210.8 24.3 133.8 162.4 1,991.2 Income before income tax expense 937.0 113.3 78.1 78.0 61.3 1,267.7 Net income 565.6 79.7 76.2 74.3 34.4 830.2 Total assets at end of fiscal year 127,468.2 31,074.9 4,871.0 10,880.6 15,819.7 190,114.4 Fiscal year ended March 31, 2016: Total revenue (1) 2,288.5 434.4 45.7 187.5 428.0 3,384.1 Total expenses (2) 1,534.2 282.6 28.7 126.2 215.8 2,187.5 Income before income tax expense 754.3 151.8 17.0 61.3 212.2 1,196.6 Net income 464.7 136.9 15.4 51.1 182.0 850.1 Total assets at end of fiscal year 133,157.1 28,985.3 4,227.5 11,616.9 15,823.4 193,810.2 Fiscal year ended March 31, 2017: Total revenue (1) 1,748.3 500.3 70.3 190.7 367.5 2,877.1 Total expenses (2) 1,712.3 303.2 29.1 136.2 215.9 2,396.7 Income before income tax expense 36.0 197.1 41.2 54.5 151.6 480.4 Net income 5.7 167.6 38.8 39.5 137.5 389.1 Total assets at end of fiscal year 138,832.3 30,262.0 4,203.3 10,629.1 16,529.6 200,456.3 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, 2017
Mizuho Financial Group, Inc., parent company	34. Mizuho Financial Group, Inc., parent company The following tables present the parent company only financial information of MHFG: Condensed balance sheets 2016 2017 (in millions of yen) Assets: Cash and due from banks 137 15,912 Interest-bearing deposits in other banks 16,305 4,278 Investments in subsidiaries and affiliated companies 8,840,003 8,993,388 Long-term loans receivable from subsidiaries 624,518 2,697,250 Other 400,590 477,375 Total 9,881,553 12,188,203 Liabilities and shareholders’ equity: Short-term borrowings 1,186,345 1,156,100 Long-term debt 584,518 2,632,250 Other liabilities 96,139 138,496 Shareholders’ equity 8,014,551 8,261,357 Total 9,881,553 12,188,203 Condensed statements of income 2015 2016 2017 (in millions of yen) Income: Dividends from subsidiaries and affiliated companies: Banking subsidiaries 316,035 272,070 300,530 Non-banking 28,633 20,814 27,618 Management fees from subsidiaries 32,163 39,267 48,594 Interest Income on Loans and Discounts 799 9,630 39,359 Other income 37,308 1,855 21,054 Total 414,938 343,636 437,155 Expenses: Operating expenses 26,855 31,063 38,927 Interest expense 8,937 11,914 38,759 Bond issuance cost 865 3,230 9,835 Other expense 1,828 5,973 7,708 Total 38,485 52,180 95,229 Equity in undistributed net income of subsidiaries 427,037 559,553 21,251 Income before income tax expense 803,490 851,009 363,177 Income tax expense 442 517 737 Net income 803,048 850,492 362,440 Condensed statements of cash flows 2015 2016 2017 (in millions of yen) Cash flows from operating activities: Net income 803,048 850,492 362,440 Adjustments and other (460,230 ) (546,946 ) (40,595 ) Net cash provided by operating activities 342,818 303,546 321,845 Cash flows from investing activities: Net change in loans (150,000 ) (479,948 ) (2,022,860 ) Purchases of premises and equipment (159,670 ) (165 ) (40,362 ) Payments for purchases of securities of subsidiaries — (2,249 ) (65,269 ) Proceeds from withdrawal of securities of subsidiaries — — 13,359 Net change in other investing activities 3,294 1,872 6,691 Net cash used in investing activities (306,376 ) (480,490 ) (2,108,441 ) Cash flows from financing activities: Net change in short-term borrowings 130,000 (10,000 ) (30,000 ) Proceeds from issuance of long-term debt 150,000 479,948 2,022,860 Repayment of long-term debt (141,200 ) (98,800 ) — Proceeds from issuance of common stock 6 5 6 Purchases of treasury stock (12 ) (13 ) (1,435 ) Dividends paid (176,186 ) (195,283 ) (190,031 ) Net change in other financing activities 1,006 1,001 971 Net cash provided by (used in) financing activities (36,386 ) 176,858 1,802,371 Net increase (decrease) in cash and due from banks 56 (86 ) 15,775 Cash and due from banks at beginning of fiscal year 167 223 137 Cash and due from banks at end of fiscal year 223 137 15,912

Basis of presentation and sum42

Basis of presentation and summary of significant accounting policies (Policies)	12 Months Ended
	Mar. 31, 2017
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”), Trust & Custody Services Bank, Ltd. (“TCSB”), 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. The MHFG Group has introduced an in-house The accompanying consolidated financial statements have been prepared in accordance with 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 and the fiscal year of certain subsidiaries ends on December 31. The necessary adjustments have been made to the consolidated financial statements if significant transactions took place during the three-month period. When determining whether to consolidate investee entities, the MHFG Group performed a careful 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 the 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.
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 due from banks	Definition of cash and due from banks For purposes of the consolidated statements of cash flows, Cash and due from banks includes cash on hand, cash items in the process of collection and noninterest-bearing deposits with banks.
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, 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 denominated in foreign currencies are translated into Japanese yen 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 9 “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 daily 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 4 “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 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”). 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 collectibility of the principal amount is uncertain, 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 5 “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 other obligors, the Group separately monitors the credit quality of each obligor without using time-based triggers. Subsequent recoveries of previously charged-off 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. In determining the appropriate level of the allowance, the MHFG Group evaluates the probable loss by category of loan based on its risk type and characteristics. 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 or listed securities. 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 small balance, homogeneous loans that are collectively evaluated for impairment and to non-homogeneous 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 within 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 back-tested on a periodic basis by comparing the allowance with the actual results subsequent to the balance sheet date.
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 Leasehold improvements 3 to 50 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 the accounts, and any gains or losses on disposal are included in Gains on disposal of premises and equipment or Occupancy expenses.
Impairment of long-lived assets	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 when triggering events occur.
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. An impairment loss is recorded to the extent the carrying amount of goodwill exceeds its estimated fair value.
Intangible assets	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 among asset management companies consist primarily of customer relationship intangibles, and are amortized over weighted-average amortization periods of 16 years and 16.9 years, respectively. See Note 3 “Business Combination” for further details of the integration among asset management companies. 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.
Pension and other employee benefits	Pension and other employee benefits MHFG and certain subsidiaries sponsor severance indemnities and pension plans, which provide defined benefits to retired employees. Periodic expense and accrued liabilities are computed based on the actuarial present value of benefits, net of investment returns expected from plan assets and their fair values at the balance sheet date. Net periodic expense is charged to Salaries and employee benefits. Net actuarial gains and losses that arise from differences between actual experience and assumptions are generally amortized over the average remaining service period of participating employees if they exceed the corridor, which is defined as the greater of 10% of plan assets or the projected benefit obligation.
Stock-based compensation	Stock-based compensation The compensation cost with regard to stock options is measured at fair value using the Black-Scholes option pricing model. The compensation cost with regard to the performance-based stock compensation is determined based upon the fair value of the shares of MHFG common stock as of the grant date and is recognized over the three year deferral period on a straight-line basis. See Note 22 “Stock-based compensation” for further details of the stock options and the performance-based stock compensation.
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 28 “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 28 “Fair value” for descriptions of valuation methodologies used for its assets and liabilities by product.
Fee and commission income	Fee and commission income Fee revenue is recognized when all of the following criteria have been met: persuasive evidence of an agreement exists, services have been rendered, the price is fixed or determinable, and collectibility is reasonably assured. Fees in respect of securities-related business and fees on funds transfer and collection services are generally recognized as revenue when the related services are performed. Fees on credit-related business, excluding loan origination fees which are deferred and recognized over the loan period as a yield adjustment, are generally recognized either at one time when the service is rendered or over the related transaction period. Fee and commission income is presented on a gross basis and exclusive of consumption taxes.
Income taxes	Income taxes Income taxes are accounted for in accordance with ASC 740, “Income Taxes” (“ASC 740”). Deferred income taxes reflect the net tax effects of (1) temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the corresponding amounts used for income tax purposes, and (2) operating loss and tax credit carryforwards. A valuation allowance is recorded for any portion of the deferred tax assets unless it is more likely than not that the deferred tax assets will be realized. 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 the possible exercise of all convertible securities, such as convertible preferred stock to the extent they are not anti-dilutive. See Note 19 “Earnings per common share” for the computation of basic and diluted earnings per common share.

Basis of presentation and sum43

Basis of presentation and summary of significant accounting policies (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule Of Useful Lives For Property Plant Equipment	The useful lives of premises and equipment are as follows: Years Buildings 3 to 50 Equipment and furniture 2 to 20 Leasehold improvements 3 to 50

Business combination (Tables)

Business combination (Tables)	12 Months Ended
	Mar. 31, 2017
Summary of Consideration Paid	The following table summarizes the consideration paid for DIAM and the amounts of the acquired assets and assumed liabilities recognized at the acquisition date, as well as the fair value at the acquisition date of the noncontrolling interest in DIAM. There were no material acquisition-related costs that were recognized separately from the acquisition of the assets and the assumption of the liabilities. At October 1, (in millions of yen) Consideration: Equity instruments (1,038,408 common shares of MHAM) 28,842 Fair value of total consideration transferred 28,842 Fair value of equity interests in DIAM held by MHFG before the business 72,106 100,948 Recognized amounts of identifiable assets acquired: Cash and due from banks 831 Interest-bearing deposits in other banks 12,873 Trading account assets 266 Investments 12,234 Premises and equipment-net 3,546 Accrued income 7,882 Intangible assets (Note) 53,037 Deferred tax assets 1,003 Other assets 2,208 Recognized amounts of identifiable liabilities assumed: Trading account liabilities 304 Income taxes payable 918 Deferred taxes liabilities 16,238 Accrued expenses 5,392 Other liabilities 3,041 Total identifiable net assets 67,987 Goodwill 76,225 Noncontrolling interest in DIAM 43,264 100,948 Note: Amount represents customer relationships subject to amortization, of which the weighted-average amortization period is 16.9 years.

Investments (Tables)

Investments (Tables)	12 Months Ended
	Mar. 31, 2017
Amortized Cost Gross Unrealized Gains and Losses and Fair Value of Investments Table	The amortized cost, gross unrealized gains and losses, and fair value of available-for-sale held-to-maturity Amortized cost Gross unrealized Gross unrealized Fair value (in millions of yen) 2016 Available-for-sale Debt securities: Japanese government bonds 15,672,171 91,420 1,015 15,762,576 Japanese local government bonds 234,587 6,097 3 240,681 U.S. Treasury bonds and federal agency securities 436,792 1,720 32 438,480 Other foreign government bonds 939,808 2,740 153 942,395 Agency mortgage-backed securities (1) 920,375 29,804 1,293 948,886 Residential mortgage-backed securities 206,882 4,254 878 210,258 Commercial mortgage-backed securities 186,525 788 523 186,790 Japanese corporate bonds and other debt securities (2) 2,079,599 15,688 420 2,094,867 Foreign corporate bonds and other debt securities (3) 839,981 8,744 1,421 847,304 Equity securities (marketable) 1,663,486 2,121,379 4,577 3,780,288 Total 23,180,206 2,282,634 10,315 25,452,525 Held-to-maturity Debt securities: Japanese government bonds 3,760,032 56,620 — 3,816,652 Agency mortgage-backed securities (4) 1,058,929 3,894 6,266 1,056,557 Total 4,818,961 60,514 6,266 4,873,209 Amortized cost Gross unrealized Gross unrealized Fair value (in millions of yen) 2017 Available-for-sale Debt securities: Japanese government bonds 10,256,512 22,782 16,408 10,262,886 Japanese local government bonds 279,864 4,841 233 284,472 U.S. Treasury bonds and federal agency securities 1,148,389 10 4,578 1,143,821 Other foreign government bonds 933,942 1,246 236 934,952 Agency mortgage-backed securities (1) 832,738 15,500 5,441 842,797 Residential mortgage-backed securities 142,879 1,838 558 144,159 Commercial mortgage-backed securities 223,105 1,092 282 223,915 Japanese corporate bonds and other debt securities (2) 1,958,472 52,046 2,286 2,008,232 Foreign corporate bonds and other debt securities (3) 909,052 3,377 1,643 910,786 Equity securities (marketable) 1,528,808 2,273,883 1,593 3,801,098 Total 18,213,761 2,376,615 33,258 20,557,118 Held-to-maturity Debt securities: Japanese government bonds 3,059,976 37,168 — 3,097,144 Agency mortgage-backed securities (4) 757,384 121 7,931 749,574 Total 3,817,360 37,289 7,931 3,846,718 Notes : (1) Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥168,604 million and ¥780,282 million, respectively, at March 31, 2016, and ¥134,240 million and ¥708,557 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Government National Mortgage Association (“Ginnie Mae”) securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. (2) Other debt securities presented in the above table primarily consist of certificates of deposit (“CDs”) and asset-backed securities (“ABS”), of which the total fair values were ¥158,446 million at March 31, 2016, and ¥155,138 million at March 31, 2017. (3) Other debt securities presented in the above table primarily consist of CDs, ABS, and collateralized loan obligations (“CLO”), of which the total fair values were ¥201,952 million at March 31, 2016, and ¥258,059 million at March 31, 2017. (4) All Agency mortgage-backed securities presented in the above table are Ginnie Mae securities.
Investments Classified by Contractual Maturity Date	Securities not due at a single maturity date and securities embedded with call or prepayment options, such as mortgage-backed securities, are included in the table below based on their contractual maturities. Amortized cost Due in one Due after one Due after five Due after Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 3,147,992 5,538,724 1,569,796 — 10,256,512 Japanese local government bonds 41,307 101,307 136,701 549 279,864 U.S. Treasury bonds and federal agency securities 1,065,881 — 82,508 — 1,148,389 Other foreign government bonds 757,093 170,836 6,013 — 933,942 Agency mortgage-backed securities — — — 832,738 832,738 Residential mortgage-backed securities — — — 142,879 142,879 Commercial mortgage-backed securities 7,000 116,633 99,472 — 223,105 Japanese corporate bonds and other debt securities 471,592 866,455 431,097 189,328 1,958,472 Foreign corporate bonds and other debt securities 450,865 399,330 55,808 3,049 909,052 Total 5,941,730 7,193,285 2,381,395 1,168,543 16,684,953 Held-to-maturity Debt securities: Japanese government bonds 1,100,032 1,480,073 479,871 — 3,059,976 Agency mortgage-backed securities — — — 757,384 757,384 Total 1,100,032 1,480,073 479,871 757,384 3,817,360 Fair value Due in one Due after one Due after five Due after Total (in millions of yen) Available-for-sale Debt securities: Japanese government bonds 3,151,367 5,549,293 1,562,226 — 10,262,886 Japanese local government bonds 41,366 102,326 140,138 642 284,472 U.S. Treasury bonds and federal agency securities 1,065,415 — 78,406 — 1,143,821 Other foreign government bonds 757,094 171,662 6,196 — 934,952 Agency mortgage-backed securities — — — 842,797 842,797 Residential mortgage-backed securities — — — 144,159 144,159 Commercial mortgage-backed securities 7,008 116,641 100,266 — 223,915 Japanese corporate bonds and other debt securities 472,047 869,226 433,132 233,827 2,008,232 Foreign corporate bonds and other debt securities 451,370 400,669 55,728 3,019 910,786 Total 5,945,667 7,209,817 2,376,092 1,224,444 16,756,020 Held-to-maturity Debt securities: Japanese government bonds 1,102,730 1,491,570 502,844 — 3,097,144 Agency mortgage-backed securities — — — 749,574 749,574 Total 1,102,730 1,491,570 502,844 749,574 3,846,718
Other-Than-Temporary Impairment Losses on Available-for-Sale Securities	The following table shows the other-than-temporary impairment losses on available-for-sale held-to-maturity 2015 2016 2017 (in millions of yen) Available-for-sale Debt securities 450 4,020 138 Equity securities 618 34,041 12,029 Total 1,068 38,061 12,167
Unrealized Loss Position Investments	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 Gross Fair Gross Fair Gross (in millions of yen) 2016 Available-for-sale Debt securities: Japanese government bonds 1,531,400 692 74,427 323 1,605,827 1,015 Japanese local government bonds 3,434 3 — — 3,434 3 U.S. Treasury bonds and federal agency securities 315,425 32 — — 315,425 32 Other foreign government bonds 225,493 139 225 14 225,718 153 Agency mortgage-backed securities (1) 15,965 86 58,147 1,207 74,112 1,293 Residential mortgage-backed securities 2,417 3 39,984 875 42,401 878 Commercial mortgage-backed securities 40,471 300 22,465 223 62,936 523 Japanese corporate bonds and other debt securities 360,782 348 20,109 72 380,891 420 Foreign corporate bonds and other debt securities 186,478 972 22,090 449 208,568 1,421 Equity securities (marketable) 71,262 4,515 180 62 71,442 4,577 Total 2,753,127 7,090 237,627 3,225 2,990,754 10,315 Held-to-maturity Debt securities: Agency mortgage-backed securities (2) 394,673 5,384 101,892 882 496,565 6,266 Total 394,673 5,384 101,892 882 496,565 6,266 2017 Available-for-sale Debt securities: Japanese government bonds 5,574,649 15,796 95,612 612 5,670,261 16,408 Japanese local government bonds 58,700 233 — — 58,700 233 U.S. Treasury bonds and federal agency securities 1,013,962 4,578 — — 1,013,962 4,578 Other foreign government bonds 334,300 230 8,327 6 342,627 236 Agency mortgage-backed securities (1) 195,887 3,705 42,501 1,736 238,388 5,441 Residential mortgage-backed securities 5,873 3 28,994 555 34,867 558 Commercial mortgage-backed securities 8,314 218 17,634 64 25,948 282 Japanese corporate bonds and other debt securities 470,602 2,062 158,713 224 629,315 2,286 Foreign corporate bonds and other debt securities 202,347 1,353 77,699 290 280,046 1,643 Equity securities (marketable) 30,688 383 4,117 1,210 34,805 1,593 Total 7,895,322 28,561 433,597 4,697 8,328,919 33,258 Held-to-maturity Debt securities: Agency mortgage-backed securities (2) 460,882 3,518 259,466 4,413 720,348 7,931 Total 460,882 3,518 259,466 4,413 720,348 7,931 Notes : (1) Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥69,805 million and ¥4,307 million, respectively, at March 31, 2016, and ¥134,118 million and ¥104,270 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise. (2) All Agency mortgage-backed securities presented in the above table are Ginnie Mae securities.
Realized Gains (Losses) on Sales of Available-for-Sale Securities	The following table shows the realized gains and losses on sales of available-for-sale available-for-sale 2015 2016 2017 (in millions of yen) Gross realized gains 220,250 297,344 353,036 Gross realized losses (14,670 ) (45,376 ) (21,163 ) Net realized gains (losses) on sales of available-for-sale 205,580 251,968 331,873
Other Investments Disclosure	The following table summarizes the composition of Other investments at March 31, 2016 and 2017: 2016 2017 (in millions of yen) Equity method investments 258,180 249,679 Investments held by consolidated investment companies 42,045 37,462 Other equity interests 313,221 307,928 Total 613,446 595,069

Loans (Tables)

Loans (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Accounts, Notes, Loans and Financing Receivable	The table below presents loans outstanding by domicile and industry of borrower at March 31, 2016 and 2017: 2016 2017 (in millions of yen) Domestic: Manufacturing 8,344,808 8,740,281 Construction and real estate 7,733,513 7,654,016 Services 4,655,704 4,759,225 Wholesale and retail 5,408,850 5,142,003 Transportation and communications 3,267,902 3,490,415 Banks and other financial institutions 3,632,481 4,006,401 Government and public institutions 3,395,784 8,532,246 Other industries (Note) 4,619,336 4,427,349 Individuals: Mortgage loans 10,589,646 9,964,633 Other 924,408 939,971 Total domestic 52,572,432 57,656,540 Foreign: Commercial and industrial 17,319,284 16,872,448 Banks and other financial institutions 6,382,449 6,759,921 Government and public institutions 1,174,665 959,948 Other (Note) 273,695 190,724 Total foreign 25,150,093 24,783,041 Total 77,722,525 82,439,581 Less: Unearned income and deferred loan fees—net 167,156 155,675 Total loans before allowance for loan losses 77,555,369 82,283,906 Note: Other industries of Domestic and Other of Foreign include trade receivables and lease receivables of consolidated VIEs.
Financing Receivable Credit Quality Indicators	The table below presents credit quality information of loans based on the MHFG Group’s internal rating system at March 31, 2016 and 2017: Normal obligors Watch obligors excluding (1) Impaired Total A-B C-D Retail (2) Other (3) E1-E2 Retail (2) Other (3) (in millions of yen) 2016 Domestic: Manufacturing 4,859,256 2,681,958 103,343 148,102 163,213 12,473 2,958 373,505 8,344,808 Construction and real estate 3,956,798 2,709,617 601,251 157,057 215,244 16,408 255 76,883 7,733,513 Services 2,611,296 1,674,328 195,140 2,380 81,704 24,846 — 66,010 4,655,704 Wholesale and retail 2,240,228 2,552,552 223,677 57,865 147,404 39,486 546 147,092 5,408,850 Transportation and communications 2,410,967 695,697 86,094 380 35,090 10,518 — 29,156 3,267,902 Banks and other financial institutions 2,719,047 881,405 2,234 3,788 22,303 264 — 3,440 3,632,481 Government and public institutions 3,181,241 4,047 — 210,496 — — — — 3,395,784 Other industries (4) 1,954,222 685,258 3,501 1,929,712 7,053 329 35,315 3,946 4,619,336 Individuals — 259,646 10,891,538 107,131 34,744 96,729 1,659 122,607 11,514,054 Total domestic 23,933,055 12,144,508 12,106,778 2,616,911 706,755 201,053 40,733 822,639 52,572,432 Foreign: Commercial and industrial 9,468,077 4,966,929 46 2,214,584 422,567 — 80,339 166,742 17,319,284 Banks and other financial institutions 5,129,904 550,380 — 656,969 45,196 — — — 6,382,449 Government and public institutions 942,366 224,514 — 2,940 4,801 — — 44 1,174,665 Other (4) — 6,308 8,336 258,363 132 10 268 278 273,695 Total foreign 15,540,347 5,748,131 8,382 3,132,856 472,696 10 80,607 167,064 25,150,093 Total 39,473,402 17,892,639 12,115,160 5,749,767 1,179,451 201,063 121,340 989,703 77,722,525 2017 Domestic: Manufacturing 5,313,232 2,599,760 90,825 67,734 276,771 11,589 1,314 379,056 8,740,281 Construction and real estate 4,199,022 2,641,436 558,321 15,585 165,836 16,023 317 57,476 7,654,016 Services 2,699,487 1,687,515 185,577 910 95,973 23,189 204 66,370 4,759,225 Wholesale and retail 2,244,214 2,369,842 200,003 22,785 124,846 32,911 501 146,901 5,142,003 Transportation and communications 2,584,367 739,781 82,543 1,092 50,319 9,698 — 22,615 3,490,415 Banks and other financial institutions 3,050,605 887,527 1,894 37,907 21,574 353 — 6,541 4,006,401 Government and public institutions 4,059,349 1,600 — 4,471,297 — — — — 8,532,246 Other industries (4) 1,873,137 591,109 3,535 1,906,756 4,613 410 41,179 6,610 4,427,349 Individuals — 289,809 10,312,739 80,566 26,288 89,066 1,434 104,702 10,904,604 Total domestic 26,023,413 11,808,379 11,435,437 6,604,632 766,220 183,239 44,949 790,271 57,656,540 Foreign: Commercial and industrial 9,310,432 4,814,906 173 2,153,757 312,275 — 90,722 190,183 16,872,448 Banks and other financial institutions 5,628,387 592,380 — 480,806 58,348 — — — 6,759,921 Government and public institutions 741,478 214,558 — 1,082 2,801 — — 29 959,948 Other (4) — 6,535 9,439 173,464 124 8 753 401 190,724 Total foreign 15,680,297 5,628,379 9,612 2,809,109 373,548 8 91,475 190,613 24,783,041 Total 41,703,710 17,436,758 11,445,049 9,413,741 1,139,768 183,247 136,424 980,884 82,439,581 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) Amounts represent small balance, homogeneous loans which are subject to pool allocations. (3) Non-impaired (4) Other industries of Domestic and Other of Foreign include trade receivables and lease receivables of consolidated VIEs.
Impaired Financing Receivables	The table below presents impaired loans information at March 31, 2016 and 2017: Recorded investment (1) Unpaid Related (3) Average Interest (4) Requiring an Not (2) Total (in millions of yen) 2016 Domestic: Manufacturing 365,361 8,144 373,505 379,642 138,676 410,491 7,930 Construction and real estate 59,883 17,000 76,883 87,516 10,130 89,075 1,246 Services 56,695 9,315 66,010 72,603 19,095 69,525 1,292 Wholesale and retail 134,425 12,667 147,092 157,215 46,304 149,324 2,376 Transportation and communications 25,665 3,491 29,156 30,497 5,694 33,119 630 Banks and other financial institutions 3,390 50 3,440 3,440 1,095 5,188 42 Other industries 3,591 355 3,946 4,132 799 2,665 64 Individuals 63,367 59,240 122,607 135,325 6,085 133,015 2,058 Total domestic 712,377 110,262 822,639 870,370 227,878 892,402 15,638 Foreign: Total foreign 148,471 18,593 167,064 180,870 61,308 186,440 2,629 Total 860,848 128,855 989,703 1,051,240 289,186 1,078,842 18,267 2017 Domestic: Manufacturing 372,241 6,815 379,056 383,812 148,777 375,895 2,859 Construction and real estate 46,130 11,346 57,476 66,006 6,367 66,796 877 Services 58,366 8,004 66,370 72,261 20,122 66,050 1,173 Wholesale and retail 133,466 13,435 146,901 155,023 52,341 148,865 2,261 Transportation and communications 19,386 3,229 22,615 23,568 5,968 24,035 371 Banks and other financial institutions 2,601 3,940 6,541 6,873 962 5,305 50 Other industries 6,484 126 6,610 6,740 1,999 6,053 91 Individuals 51,893 52,809 104,702 114,880 4,935 114,104 1,696 Total domestic 690,567 99,704 790,271 829,163 241,471 807,103 9,378 Foreign: Total foreign 160,563 30,050 190,613 209,129 61,102 169,192 2,040 Total 851,130 129,754 980,884 1,038,292 302,573 976,295 11,418 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 small balance, homogeneous 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 small balance, homogeneous loans at March 31, 2016 and 2017 was ¥347,839 million and ¥302,251 million, respectively. (4) Amounts represent gross interest income on impaired loans which were included in Interest income on loans in the consolidated statements of income.
Troubled Debt Restructurings on Financing Receivables by Type of Restructuring	The following table presents TDRs that were entered into during the fiscal years ended March 31, 2016 and 2017: Loan forgiveness or debt to Interest rate Recorded (Note ) Charge-offs (in millions of yen) 2016 Domestic: Manufacturing 67,058 34,081 108,395 Construction and real estate — — 27,078 Services — — 43,919 Wholesale and retail — — 157,651 Transportation and communications 49 279 28,244 Banks and other financial institutions — — 6,342 Other industries — — 7,120 Individuals — — 28,163 Total domestic 67,107 34,360 406,912 Foreign: Total foreign — — 44,748 Total 67,107 34,360 451,660 2017 Domestic: Manufacturing — — 106,697 Construction and real estate — — 18,818 Services — — 45,287 Wholesale and retail — — 159,649 Transportation and communications — — 17,417 Banks and other financial institutions — — 7,933 Other industries — — 2,518 Individuals — — 17,067 Total domestic — — 375,386 Foreign: Total foreign — — 35,685 Total — — 411,071 Note: Amounts represent the book values of loans immediately after the restructurings.
Troubled Debt Restructurings on Financing Receivables Subsequently Defaulted	The following table presents payment defaults which occurred during the fiscal years ended March 31, 2016 and 2017 with respect to the loans modified as TDRs within the previous twelve months: Recorded investment 2016 2017 (in millions of yen) Domestic: Manufacturing 10,669 5,164 Construction and real estate 2,195 2,887 Services 4,824 4,471 Wholesale and retail 20,522 10,116 Transportation and communications 2,361 795 Other industries — 14 Individuals 3,864 2,288 Total domestic 44,435 25,735 Foreign: Total foreign 10,846 3,213 Total 55,281 28,948
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, 2016 and 2017: 30-59 days 60-89 days 90 days or Total past Current Total (in millions of yen) 2016 Domestic: Manufacturing 1,555 163 9,454 11,172 8,333,636 8,344,808 Construction and real estate 2,713 1,024 35,691 39,428 7,694,085 7,733,513 Services 2,479 223 7,016 9,718 4,645,986 4,655,704 Wholesale and retail 3,193 886 8,861 12,940 5,395,910 5,408,850 Transportation and communications 594 81 2,033 2,708 3,265,194 3,267,902 Banks and other financial institutions — — — — 3,632,481 3,632,481 Government and public institutions — — — — 3,395,784 3,395,784 Other industries — — 29 29 4,619,307 4,619,336 Individuals 38,682 13,570 38,413 90,665 11,423,389 11,514,054 Total domestic 49,216 15,947 101,497 166,660 52,405,772 52,572,432 Foreign: Total foreign 859 2,598 30,000 33,457 25,116,636 25,150,093 Total 50,075 18,545 131,497 200,117 77,522,408 77,722,525 2017 Domestic: Manufacturing 1,938 360 7,767 10,065 8,730,216 8,740,281 Construction and real estate 2,818 947 32,523 36,288 7,617,728 7,654,016 Services 917 217 5,914 7,048 4,752,177 4,759,225 Wholesale and retail 1,330 2,834 5,585 9,749 5,132,254 5,142,003 Transportation and communications 384 322 1,859 2,565 3,487,850 3,490,415 Banks and other financial institutions — — — — 4,006,401 4,006,401 Government and public institutions — — — — 8,532,246 8,532,246 Other industries — — 69 69 4,427,280 4,427,349 Individuals 32,995 12,291 34,846 80,132 10,824,472 10,904,604 Total domestic 40,382 16,971 88,563 145,916 57,510,624 57,656,540 Foreign: Total foreign 546 216 95,719 96,481 24,686,560 24,783,041 Total 40,928 17,187 184,282 242,397 82,197,184 82,439,581

Allowance for loan losses (Tabl

Allowance for loan losses (Tables)	12 Months Ended
	Mar. 31, 2017
Allowance for Credit Losses on Financing Receivables	Changes in Allowance for loan losses by portfolio segment for the fiscal years ended March 31, 2015, 2016 and 2017 are shown below: Corporate Retail Other Total (in millions of yen) 2015 Balance at beginning of fiscal year 501,349 95,542 29,286 626,177 Provision (credit) for loan losses (40,167 ) (33,261 ) 13,205 (60,223 ) Charge-offs (64,634 ) (3,266 ) (11,322 ) (79,222 ) Recoveries 19,086 1,454 2,743 23,283 Net charge-offs (45,548 ) (1,812 ) (8,579 ) (55,939 ) Others (Note) 7,543 — 2,701 10,244 Balance at end of fiscal year 423,177 60,469 36,613 520,259 2016 Balance at beginning of fiscal year 423,177 60,469 36,613 520,259 Provision (credit) for loan losses 33,532 (15,474 ) 16,502 34,560 Charge-offs (97,536 ) (2,173 ) (12,610 ) (112,319 ) Recoveries 17,232 1,399 2,034 20,665 Net charge-offs (80,304 ) (774 ) (10,576 ) (91,654 ) Others (Note) (8,666 ) — (3,252 ) (11,918 ) Balance at end of fiscal year 367,739 44,221 39,287 451,247 2017 Balance at beginning of fiscal year 367,739 44,221 39,287 451,247 Provision (credit) for loan losses 45,059 (10,666 ) 3,275 37,668 Charge-offs (22,901 ) (1,754 ) (6,597 ) (31,252 ) Recoveries 18,320 5,122 2,158 25,600 Net charge-offs (4,581 ) 3,368 (4,439 ) (5,652 ) Others (Note) (890 ) — (2,700 ) (3,590 ) Balance at end of fiscal year 407,327 36,923 35,423 479,673 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, 2016 and 2017: Corporate Retail Other Total (in millions of yen) 2016 Allowance for loan losses 367,739 44,221 39,287 451,247 of which individually evaluated for impairment 222,591 3,829 12,521 238,941 of which collectively evaluated for impairment 145,148 40,392 26,766 212,306 Loans (Note) 59,385,962 12,414,453 5,922,110 77,722,525 of which individually evaluated for impairment 634,049 24,768 63,280 722,097 of which collectively evaluated for impairment 58,751,913 12,389,685 5,858,830 77,000,428 2017 Allowance for loan losses 407,327 36,923 35,423 479,673 of which individually evaluated for impairment 272,714 2,922 13,306 288,942 of which collectively evaluated for impairment 134,613 34,001 22,117 190,731 Loans (Note) 61,120,654 11,722,726 9,596,201 82,439,581 of which individually evaluated for impairment 772,647 23,422 65,075 861,144 of which collectively evaluated for impairment 60,348,007 11,699,304 9,531,126 81,578,437 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, 2017
Property, Plant and Equipment	Premises and equipment at March 31, 2016 and 2017 consist of the following: 2016 2017 (in millions of yen) Land 552,205 575,054 Buildings 827,458 807,312 Equipment and furniture 463,205 485,407 Leasehold improvements 88,195 93,967 Construction in progress 20,656 23,093 Software 1,086,124 1,308,292 Total 3,037,843 3,293,125 Less: Accumulated depreciation and amortization 1,199,853 1,251,852 Premises and equipment—net 1,837,990 2,041,273

Goodwill and intangible assets

Goodwill and intangible assets (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Goodwill	The changes in Goodwill during the fiscal years ended March 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 (in millions of yen) Balance at beginning of fiscal year 11,549 11,703 19,097 Goodwill acquired — 16,470 (1) 76,225 (2) Impairment losses recognized — (6,222 ) — Foreign exchange translation 154 (2,854 ) (146 ) Balance at end of fiscal year 11,703 19,097 95,176 Gross amount of goodwill (3) 81,254 94,473 171,432 Accumulated impairment losses 69,551 75,376 76,256 Notes: (1) Goodwill acquired is entirely related to the acquisition of Simplex Real Estate Management Inc. and Simplex REIT Partners Inc. (2) Goodwill acquired is entirely related to the acquisition of Asset Management One (see Note 3 “Business combination”). (3) 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 32 “Business segment information”.
Schedule of Intangible Assets by Major Class	The table below presents the gross carrying amount, accumulated amortization and net carrying amount of intangible assets, at March 31, 2016 and 2017: 2016 2017 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) 73,949 35,178 38,771 126,979 42,517 84,462 Other 2,864 2,208 656 2,814 2,190 624 Total 76,813 37,386 39,427 129,793 44,707 85,086 Intangible assets not subject to amortization: Total 9,224 — 9,224 9,061 — 9,061 Total 86,037 37,386 48,651 138,854 44,707 94,147 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 3 “Business combination” for further details of the integration among asset management companies. See Note 1 “Basis of presentation and summary of significant accounting policies” for further information.
Schedule of Expected Amortization Expense	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: 2018 9,465 2019 9,243 2020 8,940 2021 8,232 2022 7,699

Pledged assets and collateral (

Pledged assets and collateral (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Assets Pledged as Collateral	The following amounts, by balance sheet classification, have been pledged as collateral for borrowings and for other purposes at March 31, 2016 and 2017: 2016 2017 (in billions of yen) Interest-bearing deposits in other banks 69 51 Trading account assets 7,939 6,577 Investments 10,254 8,213 Loans 5,871 7,468 Other assets 1,322 1,588 Total 25,455 23,897
Schedule of Secured Borrowings	The associated liabilities collateralized by the above assets at March 31, 2016 and 2017 are summarized below: 2016 2017 (in billions of yen) Deposits 813 919 Payables under repurchase agreements 6,182 6,109 Payables under securities lending transactions 2,790 1,460 Other short-term borrowings 657 686 Long-term debt 5,545 4,220 Total 15,987 13,394

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Mar. 31, 2017
Deposit Liabilities Table Disclosures	The balances of time deposits and certificates of deposit issued by domestic offices in amounts of ¥10 million (approximately US$90 thousand at the Federal Reserve Bank of New York’s noon buying rate on March 31, 2017) or more and the balances of these deposits issued by foreign offices in amounts of US$100,000 or more at March 31, 2016 and 2017 are as follows: 2016 2017 (in millions of yen) Domestic offices: Time deposits 19,209,570 17,763,052 Certificates of deposit 6,432,810 5,877,100 Total 25,642,380 23,640,152 Foreign offices: Time deposits 12,708,142 14,862,230 Certificates of deposit 5,394,695 4,754,170 Total 18,102,837 19,616,400
Interest Bearing Deposit Liabilities by Maturity Disclosures	The balance and remaining maturities of time deposits and certificates of deposit issued by domestic and foreign offices at March 31, 2017 are shown in the following table: Time deposits Certificates of deposit Total (in millions of yen) Domestic offices: Due in one year or less 22,800,247 5,821,000 28,621,247 Due after one year through two years 2,024,310 56,100 2,080,410 Due after two years through three years 1,206,888 — 1,206,888 Due after three years through four years 349,896 — 349,896 Due after four years through five years 346,569 — 346,569 Due after five years 133,581 — 133,581 Total 26,861,491 5,877,100 32,738,591 Foreign offices: Due in one year or less 14,765,251 4,599,583 19,364,834 Due after one year through two years 88,304 38,709 127,013 Due after two years through three years 5,740 55,818 61,558 Due after three years through four years — 60,067 60,067 Due after four years through five years 198 — 198 Due after five years 8,956 — 8,956 Total 14,868,449 4,754,177 19,622,626 Total 41,729,940 10,631,277 52,361,217

Short-term borrowings and lon52

Short-term borrowings and long-term debt (Tables)	12 Months Ended
	Mar. 31, 2017
Details of Other Short-Term Borrowings	Details of Other short-term borrowings at March 31, 2016 and 2017 are as follows: 2016 2017 (in millions of yen) Commercial paper and short-term notes issued by consolidated VIEs of asset-backed commercial paper programs (1) (2) 289,219 59,607 Commercial paper and short-term notes issued by MHFG and its subsidiaries (1) (3) 1,369,302 956,447 Borrowings from the Bank of Japan 324,146 355,255 Other 97,372 105,303 Total 2,080,039 1,476,612 Notes: (1) Short-term notes are issued under the laws of Japan in the form of dematerialized commercial paper, whose characteristics are economically the same as commercial paper. (2) Commercial paper and short-term notes issued by consolidated VIEs of asset-backed commercial paper programs in the above table consist of commercial paper and short-term notes, of which the amounts were ¥232,538 million and ¥56,681 million, respectively, at March 31, 2016, and ¥24,559 million and ¥35,048 million, respectively, at March 31, 2017. (3) Commercial paper and short-term notes issued by MHFG and its subsidiaries in the above table consist of commercial paper and short-term notes, of which the amounts were ¥777,602 million and ¥591,700 million, respectively, at March 31, 2016, and ¥765,147 million and ¥191,300 million, respectively, at March 31, 2017.
Long-Term Obligations	Long-term debt with original maturities of more than one year at March 31, 2016 and 2017 is comprised of the following: 2016 2017 (in millions of yen) Obligations under capital leases 37,811 40,947 Loan participation borrowings 64,524 90,639 Senior borrowings and bonds 11,576,384 11,119,136 Subordinated borrowings and bonds 3,086,808 3,278,692 Total 14,765,527 14,529,414
Schedule of Long-term Debt Instruments	The following table presents the interest rates and maturities of senior borrowings and bonds, and subordinated borrowings and bonds: Interest rates (1) Maturities (2) 2016 2017 (%) (in millions of yen) Senior borrowings and bonds: fixed rate denominated in Japanese yen 0.00-10.00 Apr. 2017-Dec. 2046 7,863,984 6,011,939 fixed rate denominated in U.S. dollars 0.00-7.49 Apr. 2017-Aug. 2046 1,778,892 2,533,715 fixed rate denominated in other currencies 0.01-10.00 Apr. 2017-May. 2037 135,515 172,370 floating rate denominated in Japanese yen 0.00-23.80 Apr. 2017-Mar. 852,425 717,056 floating rate denominated in U.S. dollars 0.00-10.00 Apr. 2017-Jul. 898,840 1,557,288 floating rate denominated in other currencies 0.00-9.40 Aug. 2017-Sep. 46,728 126,768 Total 11,576,384 11,119,136 Subordinated borrowings and bonds: fixed rate denominated in Japanese yen 0.50-4.26 Apr. 2017-Perpetual 2,596,460 2,858,445 fixed rate denominated in U.S. dollars 4.30-4.70 Jul. 2022-Oct. 490,348 420,247 Total 3,086,808 3,278,692 Total 14,663,192 14,397,828 Notes: (1) The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2017. (2) Maturity information disclosed is the range of maturities at March 31, 2017. (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.
Schedule of Maturities of Long-term Debt	The following is a summary of the contractual maturities of long-term debt subsequent to March 31, 2017: (in millions of yen) Fiscal year ending March 31: 2018 1,614,386 2019 3,127,227 2020 1,733,501 2021 1,841,416 2022 1,194,536 2023 and thereafter 5,018,348 Total 14,529,414

Other assets and liabilities (T

Other assets and liabilities (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Other Assets and Other Liabilities	The following table sets forth the details of other assets and liabilities at March 31, 2016 and 2017: 2016 2017 (in millions of yen) Other assets: Accounts receivable from brokers, dealers and customers for securities transactions 1,718,769 1,564,295 Collateral provided for derivative transactions 884,651 973,404 Prepaid pension cost 612,102 682,592 Miscellaneous receivables 286,896 324,135 Margins provided for futures contracts 225,240 276,398 Security deposits 113,066 122,858 Loans held for sale 33,133 26,689 Other 823,033 1,021,958 Total 4,696,890 4,992,329 Other liabilities: Accounts payable to brokers, dealers and customers for securities transactions 2,882,824 1,400,141 Guaranteed trust principal 623,904 683,324 Collateral accepted for derivative transactions 715,894 671,691 Miscellaneous payables 442,352 481,809 Margins accepted for futures contracts 334,925 307,066 Unearned income 144,903 134,666 Factoring amounts owed to customers 242,392 53,488 Other 1,089,529 1,294,340 Total 6,476,723 5,026,525

Preferred stock (Tables)

Preferred stock (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Stockholders Equity	The following table shows the changes in the number of shares and the aggregate amount of preferred stock during the fiscal years ended March 31, 2015, 2016 and 2017: Class of stock Issued at Net Issued at Net Issued at Net Issued at (number of shares) Eleventh series class XI preferred stock (Note) 914,752,000 — 914,752,000 — 914,752,000 (914,752,000 ) — Total 914,752,000 — 914,752,000 — 914,752,000 (914,752,000 ) — Class of stock Aggregate Net Aggregate Net Aggregate Net Aggregate (in millions of yen) Eleventh series class XI preferred stock (Note) 914,752 — 914,752 — 914,752 (914,752 ) — Total 914,752 — 914,752 — 914,752 (914,752 ) — Note: In July 2016, all shares of the eleventh series class XI preferred stock were converted into common stock and cancelled.
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, 2015, 2016 and 2017: 2015 2016 2017 (shares) Balance at beginning of fiscal year 24,263,885,187 24,621,897,967 25,030,525,657 Issuance of new shares of common stock due to conversion of Eleventh series class XI preferred stock 351,822,780 403,667,690 349,677,288 Issuance of new shares of common stock due to exercise of stock acquisition rights 6,190,000 4,960,000 6,105,000 Balance at end of fiscal year 24,621,897,967 25,030,525,657 25,386,307,945
Preferred stock
Schedule of Stock by Class	The composition of preferred stock at March 31, 2015, 2016 and 2017 is as follows: 2015 Aggregate amount Number of shares Liquidation Convertible Class of stock Authorized Issued In treasury (in millions of yen) (in yen) Eleventh series class XI preferred stock (1) 914,752 914,752,000 914,752,000 701,631,100 1,000 Yes First series class XIV preferred stock (2) — 900,000,000 — — — — Second series class XIV preferred stock (2) — 900,000,000 — — — — Third series class XIV preferred stock (2) — 900,000,000 — — — — Fourth series class XIV preferred stock (2) — 900,000,000 — — — — First series class XV preferred stock (3) — 900,000,000 — — — — Second series class XV preferred stock (3) — 900,000,000 — — — — Third series class XV preferred stock (3) — 900,000,000 — — — — Fourth series class XV preferred stock (3) — 900,000,000 — — — — First series class XVI preferred stock (4) — 1,500,000,000 — — — — Second series class XVI preferred stock (4) — 1,500,000,000 — — — — Third series class XVI preferred stock (4) — 1,500,000,000 — — — — Fourth series class XVI preferred stock (4) — 1,500,000,000 — — — — Total 914,752 4,214,752,000 914,752,000 701,631,100 2016 Aggregate amount Number of shares Liquidation Convertible Class of stock Authorized Issued In treasury (in millions of yen) (in yen) Eleventh series class XI preferred stock (1) 914,752 914,752,000 914,752,000 815,828,400 1,000 Yes First series class XIV preferred stock (2) — 900,000,000 — — — — Second series class XIV preferred stock (2) — 900,000,000 — — — — Third series class XIV preferred stock (2) — 900,000,000 — — — — Fourth series class XIV preferred stock (2) — 900,000,000 — — — — First series class XV preferred stock (3) — 900,000,000 — — — — Second series class XV preferred stock (3) — 900,000,000 — — — — Third series class XV preferred stock (3) — 900,000,000 — — — — Fourth series class XV preferred stock (3) — 900,000,000 — — — — First series class XVI preferred stock (4) — 1,500,000,000 — — — — Second series class XVI preferred stock (4) — 1,500,000,000 — — — — Third series class XVI preferred stock (4) — 1,500,000,000 — — — — Fourth series class XVI preferred stock (4) — 1,500,000,000 — — — — Total 914,752 4,214,752,000 914,752,000 815,828,400 2017 Aggregate amount Number of shares Liquidation Convertible Class of stock Authorized Issued In treasury (in millions of yen) (in yen) Class XI preferred stock — 914,752,000 — — — — First series class XIV preferred stock (2) — 900,000,000 — — — — Second series class XIV preferred stock (2) — 900,000,000 — — — — Third series class XIV preferred stock (2) — 900,000,000 — — — — Fourth series class XIV preferred stock (2) — 900,000,000 — — — — First series class XV preferred stock (3) — 900,000,000 — — — — Second series class XV preferred stock (3) — 900,000,000 — — — — Third series class XV preferred stock (3) — 900,000,000 — — — — Fourth series class XV preferred stock (3) — 900,000,000 — — — — First series class XVI preferred stock (4) — 1,500,000,000 — — — — Second series class XVI preferred stock (4) — 1,500,000,000 — — — — Third series class XVI preferred stock (4) — 1,500,000,000 — — — — Fourth series class XVI preferred stock (4) — 1,500,000,000 — — — — Total — 4,214,752,000 — — Notes: (1) The aggregate amount and number of issued shares include the preferred stock in treasury which has been converted into common stock but not yet cancelled. (2) The total number of authorized shares from first to fourth series class XIV preferred stock shall not exceed 900,000,000. (3) The total number of authorized shares from first to fourth series class XV preferred stock shall not exceed 900,000,000. (4) The total number of authorized shares from first to fourth series class XVI preferred stock shall not exceed 1,500,000,000.

Dividends (Tables)

Dividends (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Dividends Payable	The following table shows dividends on preferred stock and common stock during the fiscal years ended March 31, 2015, 2016 and 2017: 2015 Cash dividends Class of stock Per share In aggregate (in yen) (in millions of yen) Eleventh series class XI preferred stock 20 5,906 Common stock 7 170,231 Total 176,137 2016 Cash dividends Class of stock Per share In aggregate (in yen) (in millions of yen) Eleventh series class XI preferred stock 20 3,572 Common stock 7.75 191,693 Total 195,265 2017 Cash dividends Class of stock Per share In aggregate (in yen) (in millions of yen) Eleventh series class XI preferred stock (Note) 10 989 Common stock 7.50 189,013 Total 190,002 Note: In July 2016, all shares of the eleventh series class XI preferred stock were converted into common stock and cancelled. Consequently, the amount for the fiscal year does not include interim dividends.

Accumulated other comprehensi56

Accumulated other comprehensive income (Tables)	12 Months Ended
	Mar. 31, 2017
Changes in Each Component of Accumulated Other Comprehensive Income, Net Of Tax	Changes in each component of AOCI for the fiscal years ended March 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 (in millions of yen) AOCI, balance at beginning of fiscal year, previously reported 1,117,877 2,041,005 1,469,308 Cumulative effect of change in accounting principles (Notes 2 and 25) — — 330 AOCI, balance at beginning of fiscal year, adjusted 1,117,877 2,041,005 1,469,638 Net unrealized gains (losses) on available-for-sale Balance at beginning of fiscal year, previously reported 1,123,272 1,747,607 1,409,459 Cumulative effect of change in accounting principles — — (85 ) Balance at beginning of fiscal year, adjusted 1,123,272 1,747,607 1,409,374 Unrealized holding gains (losses) during year 763,115 (189,479 ) 273,844 Less: reclassification adjustments for losses (gains) included in net income (138,780 ) (148,669 ) (221,916 ) Change during year 624,335 (338,148 ) 51,928 Balance at end of fiscal year 1,747,607 1,409,459 1,461,302 Foreign currency translation adjustments: Balance at beginning of fiscal year, previously reported (6,434 ) 129,179 6,310 Cumulative effect of change in accounting principles — — 415 Balance at beginning of fiscal year, adjusted (6,434 ) 129,179 6,725 Foreign currency translation adjustments during year 134,104 (122,081 ) (11,920 ) Less: reclassification adjustments for losses (gains) included in net income 1,509 (788 ) (340 ) Change during year 135,613 (122,869 ) (12,260 ) Balance at end of fiscal year 129,179 6,310 (5,535 ) Pension liability adjustments: Balance at beginning of fiscal year, previously reported 1,039 164,219 53,539 Unrealized gains (losses) during year 163,191 (107,497 ) 11,561 Less: reclassification adjustments for losses (gains) included in net income (11 ) (3,183 ) 296 Change during year 163,180 (110,680 ) 11,857 Balance at end of fiscal year 164,219 53,539 65,396 Total other comprehensive income (loss), net of tax attributable to MHFG shareholders 923,128 (571,697 ) 51,525 AOCI, balance at end of fiscal year 2,041,005 1,469,308 1,521,163
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, 2017: Before tax (1) Tax effect (2) Net of tax before Net of tax attributable to (2) Net of tax attributable 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 319,707 (97,729 ) 221,978 (62 ) 221,916 Investment gains (losses)—net Foreign currency translation adjustments 340 — 340 — 340 Foreign exchange gains (losses)-net Pension liability adjustments (476 ) 178 (298 ) 2 (296 ) Salaries and employee benefits Total 319,571 (97,551 ) 222,020 (60 ) 221,960 Notes: (1) The amounts in the Before tax column are recorded in each account presented under the heading “Affected line items in the consolidated statements of income”. (2) The amounts in the Tax effect column and Net of tax attributable to noncontrolling interests column are recorded in Income tax expense and Net income (loss) attributable to noncontrolling interests in the consolidated statements of income, respectively.

Regulatory matters (Tables)

Regulatory matters (Tables)	12 Months Ended
	Mar. 31, 2017
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 2016 March 2017 March 2018 March 2019 March 2020 March 2021 March 2022 Minimum Common Equity Tier 1 capital 4.5 % 4.5 % 4.5 % 4.5 % 4.5 % 4.5 % 4.5 % Minimum Tier 1 capital 6.0 % 6.0 % 6.0 % 6.0 % 6.0 % 6.0 % 6.0 % Minimum total capital 8.0 % 8.0 % 8.0 % 8.0 % 8.0 % 8.0 % 8.0 % Capital conservation buffer 0.625 % 1.25 % 1.875 % 2.5 % 2.5 % 2.5 % 2.5 % Phase out of recognition of capital instruments that no longer qualify as capital 60.0 % 50.0 % 40.0 % 30.0 % 20.0 % 10.0 % 0.0 % Phase-in 60.0 % 80.0 % 100.0 % 100.0 % 100.0 % 100.0 % 100.0 % Additional loss absorbency requirements for G-SIBs D-SIBs (Note) 0.25 % 0.50 % 0.75 % 1.0 % 1.0 % 1.0 % 1.0 % Note: Figures assume that the additional loss absorbency requirements applied to the Group as a G-SIB D-SIB
Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations	Capital adequacy ratios of MHFG, MHBK, and MHTB as of March 31, 2016 and 2017 calculated in accordance with Japanese GAAP and the guidelines established by the Financial Services Agency are set forth in the following table: 2016 2017 Amount Ratio Amount Ratio (in billions of yen, except percentages) Consolidated: MHFG: Common Equity Tier 1 capital: Required (Note) 3,361 5.375 3,857 6.25 Actual 6,566 10.50 7,002 11.34 Tier 1 capital: Required (Note) 4,299 6.875 4,783 7.75 Actual 7,905 12.64 8,212 13.30 Total risk-based capital: Required (Note) 5,550 8.875 6,017 9.75 Actual 9,639 15.41 10,051 16.28 MHBK: Common Equity Tier 1 capital: Required 2,555 4.50 2,541 4.50 Actual 6,142 10.81 6,304 11.16 Tier 1 capital: Required 3,406 6.00 3,388 6.00 Actual 7,244 12.75 7,536 13.34 Total risk-based capital: Required 4,542 8.00 4,517 8.00 Actual 8,780 15.46 9,149 16.20 MHTB: Common Equity Tier 1 capital: Required 109 4.50 112 4.50 Actual 440 18.21 466 18.73 Tier 1 capital: Required 145 6.00 149 6.00 Actual 440 18.21 466 18.73 Total risk-based capital: Required 193 8.00 199 8.00 Actual 472 19.52 485 19.47 Non-consolidated: MHBK: Common Equity Tier 1 capital: Required 2,489 4.50 2,432 4.50 Actual 5,892 10.65 6,057 11.20 Tier 1 capital: Required 3,318 6.00 3,243 6.00 Actual 7,004 12.66 7,316 13.53 Total risk-based capital: Required 4,424 8.00 4,324 8.00 Actual 8,576 15.50 8,938 16.53 MHTB: Common Equity Tier 1 capital: Required 109 4.50 113 4.50 Actual 448 18.52 475 18.98 Tier 1 capital: Required 145 6.00 150 6.00 Actual 448 18.52 475 18.98 Total risk-based capital: Required 194 8.00 200 8.00 Actual 480 19.80 493 19.70 Note: The required ratios disclosed above, at March 31, 2016 and 2017, include the transitional capital conservation buffer of 0.625% and 1.25%, respectively, and the transitional additional loss absorbency requirements for G-SIBs D-SIBs

Earnings per common share (Tabl

Earnings per common share (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Calculation of Numerator and Denominator in Earnings Per Share	The following table sets forth the computation of basic and diluted earnings per common share for the fiscal years ended March 31, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Net income: Net income attributable to MHFG shareholders 803,048 850,492 362,440 Less: Net income attributable to preferred shareholders 4,910 2,430 — Net income attributable to common shareholders 798,138 848,062 362,440 Effect of dilutive securities: Convertible preferred stock 4,910 2,430 — Net income attributable to common shareholders after assumed conversions 803,048 850,492 362,440 2015 2016 2017 (thousands of shares) Shares: Weighted average common shares outstanding 24,368,116 24,806,161 25,285,899 Effect of dilutive securities: Convertible preferred stock (Note) 994,745 563,044 82,993 Stock options 18,186 17,828 11,410 Weighted average common shares after assumed conversions 25,381,047 25,387,033 25,380,302 2015 2016 2017 (in yen) Amounts per common share: Basic net income per common share 32.75 34.19 14.33 Diluted net income per common share 31.64 33.50 14.28 Note: The number of common shares after assumed conversion of the convertible preferred stock is based on the applicable conversion prices.

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Components of Income Tax Expense	The following table presents the components of Income tax expense for the fiscal years ended March 31, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Current: Domestic 184,180 162,408 130,164 Foreign 71,250 61,009 68,512 Total current tax expense 255,430 223,417 198,676 Deferred: Domestic 187,134 127,185 (99,831 ) Foreign (5,144 ) (4,060 ) (7,601 ) Total deferred tax expense 181,990 123,125 (107,432 ) Total income tax expense 437,420 346,542 91,244
Comprehensive Income Tax (Expense) Benefit Components	The detailed amounts recorded directly in Equity are as follows: 2015 2016 2017 (in millions of yen) Net unrealized gains (losses) on available-for-sale Unrealized gains (losses) 403,690 (97,339 ) 112,467 Less: reclassification adjustments (65,699 ) (65,207 ) (97,729 ) Total 337,991 (162,546 ) 14,738 Foreign currency translation adjustments: Unrealized gains (losses) — 126 — Less: reclassification adjustments — — — Total — 126 — Pension liability adjustments: Unrealized gains (losses) 87,654 (51,661 ) 4,785 Less: reclassification adjustments (16 ) (1,317 ) 178 Total 87,638 (52,978 ) 4,963 Total tax effect before allocation to noncontrolling interests 425,629 (215,398 ) 19,701
Schedule of Effective Income Tax Rate Reconciliation	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, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen, except tax rates) Income before income tax expense 1,267,653 1,196,605 480,375 Effective statutory tax rate 35.64 % 33.06 % 30.86 % Income tax calculated at the statutory tax rate 451,792 395,598 148,244 Income not subject to tax (20,911 ) (12,888 ) (7,521 ) Expenses not deductible for tax purposes 1,532 1,521 1,483 Tax rate differentials of subsidiaries (3,517 ) (2,208 ) (2,165 ) Change in valuation allowance (4,444 ) (1,897 ) 112,781 (3) Change in undistributed earnings of subsidiaries 16,084 (16,112 ) 5,217 Change in net operating loss carryforwards resulting from intercompany capital transactions (1,290 ) (1,446 ) 647 Effect of enacted change in tax rates (21,714 ) (1) (7,976 ) (2) — Reversal of outside basis differences — — (159,119 ) (3) Other 19,888 (8,050 ) (8,323 ) Income tax expense 437,420 346,542 91,244 Notes: (1) On March 31, 2015, the National Diet of Japan approved a bill affecting the statutory tax rates of MHFG and its domestic subsidiaries. As a result, the statutory tax rate in respect of MHFG’s tax returns for the fiscal year ended March 31, 2016 was reduced to 33.06% from the previous rate of 35.64%. In addition, the tax rate for the fiscal years ended March 31, 2017 and thereafter was reduced to 32.26%. The decrease in the MHFG Group’s balance of net deferred tax liabilities, reflecting such tax rate reductions, was recognized as a reduction to Income tax expense in the fiscal year ended March 31, 2015. (2) On March 29, 2016, the National Diet of Japan approved a bill affecting the statutory tax rates of MHFG and its domestic subsidiaries. As a result, the statutory tax rate in respect of MHFG’s tax returns for the fiscal year ended March 31, 2017 was reduced to 30.86% from the previous rate of 32.26%, and the statutory tax rate for the fiscal year ending March 31, 2018 will be the same rate. In addition, the tax rate for the fiscal years ending March 31, 2019 and thereafter will be 30.62%. The decrease in the Group’s balance of net deferred tax liabilities, reflecting such tax rate reductions, was recognized as a reduction to Income tax expense in the fiscal year ended March 31, 2016. (3) These amounts for the fiscal year ended March 31, 2017 represent mainly the reversal of an outside basis difference related to certain foreign subsidiaries due to their organizational restructuring and the related increase in the valuation allowance.
Schedule of Deferred Tax Assets and Liabilities	The components of net deferred tax assets (liabilities) at March 31, 2016 and 2017 are as follows: 2016 2017 (in millions of yen) Deferred tax assets: Investments 522,197 497,629 Allowance for loan losses 178,683 184,366 Trading securities — 30,841 Derivative financial instruments — 14,537 Premises and equipment — 3,594 Net operating loss carryforwards (1) (2) 341,572 452,166 Other 170,414 190,083 1,212,866 1,373,216 Valuation allowance (2) (339,922 ) (438,344 ) Deferred tax assets, net of valuation allowance 872,944 934,872 Deferred tax liabilities: Available-for-sale 710,497 724,160 Prepaid pension cost and accrued pension liabilities 174,959 195,620 Undistributed earnings of subsidiaries 11,944 17,161 Derivative financial instruments 56,877 — Trading securities 23,154 — Premises and equipment 1,033 — Other 38,990 74,886 Deferred tax liabilities 1,017,454 1,011,827 Net deferred tax assets (liabilities) (144,510 ) (76,955 ) Notes: (1) The amount includes ¥268,544 million and ¥271,266 million related to MHFG’s net operating loss carryforwards resulting mainly from intercompany capital transactions as of March 31, 2016 and 2017, respectively. The tax effect of the net operating loss carryforwards is offset by a full valuation allowance because MHFG experienced a significant expiration of net operating loss carryforwards of ¥1,262 billion in March 2013, which is negative evidence outweighing any positive evidence. Furthermore, MHFG is a holding company whose primary sources of future taxable income are management fees from subsidiaries that are not sufficient to realize deferred tax assets related to the net operating loss carryforwards. (2) The amount includes ¥115,698 million related to MHSC’s net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2017. The tax effect of the net operating loss carryforwards is substantially offset by ¥90,204 million 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, 2016 and 2017: Deferred tax assets Valuation allowance Deferred tax assets, net of valuation allowance (in billions of yen) 2016 Japan (1) 270 (270 ) — The United States 16 (8 ) 8 The United Kingdom (2) 53 (53 ) — Others 3 (3 ) — Total 342 (334 ) 8 2017 Japan (3) 388 (362 ) 26 The United States 15 (3 ) 12 The United Kingdom (2) 46 (46 ) — Others 3 (3 ) — Total 452 (414 ) 38 Notes: (1) ¥265 billion of the Japan deferred tax assets of ¥270 billion is related to MHFG, which is offset by a full valuation allowance, and will expire during the fiscal year ending March 31, 2018. (2) The United Kingdom net operating loss carryforwards may be carried forward indefinitely for the tax purposes. (3) ¥265 billion of the Japan deferred tax assets of ¥388 billion is related to MHFG, which is offset by a full valuation allowance, and will expire during the fiscal year ending March 31, 2018. In addition, ¥116 billion of the Japan deferred tax assets is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026.
Rollforward of Valuation Allowance	The following table presents a roll-forward of the valuation allowance for the fiscal years ended March 31, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Balance at beginning of fiscal year 443,847 388,551 339,922 Changes that directly affected Income tax expense (4,444 ) (1,897 ) 112,781 Changes that did not affect Income tax expense: Expiration of net operating loss carryforwards — — — Others (50,852 ) (46,732 ) (14,359 ) Total (50,852 ) (46,732 ) (14,359 ) Balance at end of fiscal year 388,551 339,922 438,344
Summary of Operating Loss Carryforwards	These carryforwards are scheduled to expire as follows: Net operating loss (in billions of yen) Fiscal year ending March 31: 2018 865 2019 4 2020 — 2021 — 2022 1 2023 and thereafter (Note) 720 Total 1,590 Note: Including the net operating loss carryforwards which may be carried forward indefinitely in the United Kingdom.
Reconciliation Of Unrecognized Tax Benefits	The following table is a roll-forward of unrecognized tax benefits for the fiscal years ended March 31, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Total unrecognized tax benefits at beginning of fiscal year 1,691 1,632 1,300 Gross amount of increases (decreases) related to positions taken during prior years (37 ) (415 ) 167 Gross amount of increases related to positions taken during the current year 346 181 409 Amount of decreases related to settlements (652 ) — — Foreign exchange translation 284 (98 ) (9 ) Total unrecognized tax benefits at end of fiscal year 1,632 1,300 1,867

Pension and other employee be60

Pension and other employee benefit plans (Tables)	12 Months Ended
	Mar. 31, 2017
Components of Net Periodic Costs	The following table presents the components of net periodic cost of the severance indemnities and pension plans for the fiscal years ended March 31, 2015, 2016 and 2017: 2015 2016 2017 (in millions of yen) Service cost-benefits earned during the fiscal year 33,578 38,032 44,367 Interest costs on projected benefit obligations 13,060 10,479 5,724 Expected return on plan assets (38,087 ) (40,603 ) (35,969 ) Amortization of prior service benefits (195 ) (195 ) (195 ) Amortization of net actuarial loss (gain) 150 (4,108 ) 780 Special termination benefits 5,504 4,456 3,857 Net periodic benefit cost 14,010 8,061 18,564
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	Other changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before-tax 2016 2017 (in millions of yen) Net actuarial gain (loss) (160,132 ) 15,645 Amortization of net actuarial loss (gain) (4,108 ) 780 Amortization of prior service benefits (195 ) (195 ) Total recognized in other comprehensive income (loss) before-tax (164,435 ) 16,230
Schedule of Assumptions Used	Weighted-average assumptions used to determine benefit obligations and net periodic benefit cost are as follows: 2015 2016 2017 Weighted-average assumptions used to determine benefit obligations at fiscal year end: Discount rates 0.76 % 0.37 % 0.47 % Rates of increase in future compensation levels 2.00-4.80 % 1.80-4.80 % 1.80-4.80 % Weighted-average assumptions used to determine net periodic benefit cost during the year: Discount rates 0.96 % 0.76 % 0.37 % Rates of increase in future compensation levels 2.00-4.80 % 2.00-4.80 % 1.80-4.80 % Expected rates of return on plan assets 2.17 % 1.95 % 1.73 %
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, 2016 and 2017 for the plans of MHFG and its subsidiaries: 2016 2017 (in millions of yen) Change in benefit obligations: Benefit obligations at beginning of fiscal year 1,392,459 1,495,208 Service cost 38,032 44,367 Interest cost 10,479 5,724 Plan participants’ contributions 1,192 1,215 Actuarial loss (gain) 125,122 67,335 Foreign exchange translation (4,054 ) (2,159 ) Benefits paid (51,392 ) (51,899 ) Lump-sum (16,630 ) (13,898 ) Benefit obligations at end of fiscal year 1,495,208 1,545,893 Change in plan assets: Fair value of plan assets at beginning of fiscal year 2,081,600 2,082,996 Actual return (negative return) on plan assets 5,058 118,714 Foreign exchange translation (3,312 ) (3,273 ) Employer contributions 49,850 53,059 Plan participants’ contributions 1,192 1,215 Benefits paid (51,392 ) (51,899 ) Fair value of plan assets at end of fiscal year 2,082,996 2,200,812 Funded status 587,788 654,919 Amounts recognized in the consolidated balance sheets consist of: Prepaid pension cost 612,102 682,592 Accrued pension liability (24,314 ) (27,673 ) Net amount recognized 587,788 654,919 Amounts recognized in Accumulated other comprehensive income (loss) before-tax Prior service benefits (cost) (1,025 ) (1,220 ) Net actuarial gain (loss) 57,619 74,044 Net amount recognized 56,594 72,824 Note: The aggregated accumulated benefit obligations of these plans were ¥1,493,393 million and ¥1,544,039 million, as of March 31, 2016 and 2017, respectively. The defined benefit plans generally employ a multi-variable and non-linear lump-sum
Schedule of Accumulated Benefit Obligations in Excess of Fair Value 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, 2016 and 2017: 2016 2017 (in millions of yen) Plans with projected benefit obligations in excess of plan assets: Projected benefit obligations 50,554 57,980 Fair value of plan assets 26,240 30,306 Plans with accumulated benefit obligations in excess of plan assets: Accumulated benefit obligations 48,738 56,125 Fair value of plan assets 26,240 30,306 Note: The plans with projected benefit obligations in excess of plan assets include those with accumulated benefit obligations in excess of plan assets.
Schedule of Allocation of Plan Assets	MHFG and certain subsidiaries’ target allocation for the plan assets, excluding those of the employee retirement benefit trusts, at March 31, 2017 is as follows: Asset category Asset ratio Japanese equity securities 5.00 % Japanese debt securities 44.00 % Foreign equity securities 25.00 % Foreign debt securities 10.00 % General account of life insurance companies 14.00 % 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 rates.
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, 2016 and 2017, 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 28 “Fair value”. 2016 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (in billions of yen) Japanese equity securities: Common stocks (1) 1,114 1 — 1,115 1,162 — — 1,162 Pooled funds (2) 10 1 — 11 10 — — 10 Japanese debt securities: Government bonds 262 — — 262 254 — — 254 Pooled funds (2) — 1 — 1 — 2 — 2 Other — 32 — 32 — 25 — 25 Foreign equity securities: Common stocks 98 — — 98 111 — — 111 Pooled funds (2) — 2 — 2 — 2 — 2 Foreign debt securities: Government bonds 72 2 — 74 68 3 — 71 Pooled funds (2) — 8 — 8 — 7 — 7 Other — 16 — 16 — 16 — 16 General account of life insurance companies (3) — 121 — 121 — 124 — 124 Hedge funds — — — — — — — — Other 44 (4) (4 ) (5) — 40 78 1 — 79 Plan assets measured at net asset value (6) 303 338 Total assets at fair value 1,600 180 — 2,083 1,683 180 — 2,201 Notes: (1) This class represents equity securities held in the employee retirement benefit trusts of ¥1,115 billion and ¥1,162 billion at March 31, 2016 and 2017, 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. (4) Amounts primarily include cash and short-term assets carried at fair value. (5) Amounts primarily include foreign exchange contracts carried at fair value. (6) 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.
Schedule of Expected 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: 2018 66,140 2019 67,758 2020 69,578 2021 70,808 2022 71,549 2023-2027 354,180

Stock-based compensation (Table

Stock-based compensation (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Share-based Compensation, Stock Options, Activity	The following is a roll-forward of MHFG Stock Plan for the fiscal year ended March 31, 2017: Number of Weighted-average Weighted-average Aggregate (in yen) (in years) (in millions of yen) Outstanding at beginning of fiscal year 17,190,000 1 Exercised during fiscal year 6,371,000 1 Outstanding at end of fiscal year 10,819,000 1 16.49 2,196 Exercisable at end of fiscal year — — — —
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	expected to be outstanding. The expected dividend yield is based on the dividend rate of MHFG common stock at the date of grant. 2015 Risk-free interest rate 0.01 % Expected volatility 25.91 % Expected remaining term (in years) 2.46 Expected dividend yield 3.42 %
Schedule of Activities Related to Performance-based Stock Compensation	The following table presents activities related to the performance-based stock compensation for the fiscal year ended March 31, 2017: Number of shares Weighted-average grant-date fair value (per share in yen) Outstanding as of March 31, 2016 — — Granted during fiscal year 9,000,000 158.68 Vested during fiscal year — — Forfeited during fiscal year — — Outstanding as of March 31, 2017 9,000,000 158.68

Derivative financial instrume62

Derivative financial instruments (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Derivative Instruments	The following table summarizes the notional and fair value amounts of derivative instruments outstanding as of March 31, 2016 and 2017. The fair values of 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 master netting agreements in the consolidated balance sheets, or the table below. Fair value Derivative receivables (2) Derivative payables (2) 2016 Notional amount (1) Designated Not designated Designated Not designated (in billions of yen) Interest rate contracts 1,066,252 — 11,522 — 11,269 Foreign exchange contracts 141,517 4 3,126 1 2,979 Equity-related contracts 3,115 18 152 — 140 Credit-related contracts 4,826 — 43 — 37 Other contracts 327 — 59 — 55 Total 1,216,037 22 14,902 1 14,480 Fair value Derivative receivables (2) Derivative payables (2) 2017 Notional amount (1) Designated Not designated Designated Not designated (in billions of yen) Interest rate contracts 961,518 — 8,506 — 8,473 Foreign exchange contracts 167,698 2 2,743 — 2,611 Equity-related contracts 4,177 — 134 5 224 Credit-related contracts 3,696 — 35 — 36 Other contracts 360 — 23 — 22 Total 1,137,449 2 11,441 5 11,366 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.
Disclosure of Credit Derivatives	The following table summarizes the notional and fair value amounts of credit derivatives at March 31, 2016 and 2017: 2016 2017 Notional amount Fair value Notional amount Fair value (in billions of yen) Credit protection written: Investment grade 1,603 14 1,546 21 Non-investment 763 1 298 1 Total 2,366 15 1,844 22 Credit protection purchased 2,592 (9 ) 1,994 (23 ) 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
Notional And Credit Risk Amounts Of Outstanding Derivative Positions Disclosure	The following table shows the maximum potential amount of future payments for credit protection written by expiration period at March 31, 2016 and 2017: Maximum payout/Notional amount 2016 2017 (in billions of yen) One year or less 538 507 After one year through five years 1,729 1,020 After five years 99 317 Total 2,366 1,844 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.
Schedule Of Derivative Instruments Value Including Credit Risk Related Contingent Features Table	The following table shows the quantitative information about derivative instruments with credit-risk-related contingent features at March 31, 2016 and 2017: 2016 2017 (in billions of yen) Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions 790 698 Collateral provided to counterparties in the normal course of business 746 658 Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered 44 40
Designated as Hedging Instrument | Fair Value Hedging
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 years ended March 31, 2015, 2016 and 2017: Gains (losses) recorded in income 2015 Derivatives Hedged Hedge Net gain (loss) excluded (in millions of yen) Equity-related contracts (29,666 ) 28,005 — (1,661 ) Total (29,666 ) 28,005 — (1,661 ) Gains (losses) recorded in income 2016 Derivatives Hedged Hedge Net gain (loss) excluded (in millions of yen) Equity-related contracts 14,623 (18,224 ) — (3,601 ) Total 14,623 (18,224 ) — (3,601 ) Gains (losses) recorded in income 2017 Derivatives Hedged Hedge Net gain (loss) excluded (in millions of yen) Equity-related contracts (14,747 ) 11,393 — (3,354 ) Total (14,747 ) 11,393 — (3,354 )
Designated as Hedging Instrument | Net Investment Hedging
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, 2015, 2016 and 2017: Gains (losses) recorded in income and other comprehensive income (“OCI”) 2015 2016 2017 Effective portion Ineffective portion Effective portion Ineffective portion Effective portion Ineffective portion (in millions of yen) Financial instruments hedging foreign exchange risk (53,252 ) (2,678 ) 46,697 696 16,767 47 Total (53,252 ) (2,678 ) 46,697 696 16,767 47 Note: No amount related to the effective portion of net investment hedges was reclassified from Accumulated other comprehensive income to earnings for the fiscal year ended March 31, 2015. Related to the effective portion of net investment hedges, gains of ¥345 million and ¥41 million were reclassified from Accumulated other comprehensive income to earnings for the fiscal years ended March 31, 2016 and 2017, respectively.
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, 2015, 2016 and 2017: Gains (losses) recorded in income 2015 2016 2017 (in millions of yen) Interest rate contracts 265,324 319,225 (209,361 ) Foreign exchange contracts (93,601 ) 65,101 37,129 Equity-related contracts (1) (100,326 ) 21,571 5,131 Credit-related contracts (2) (18,007 ) (6,960 ) (6,694 ) Other contracts 368 2,015 742 Total 53,758 400,952 (173,053 ) Notes: (1) The net gain (loss) excluded from the assessment of the effectiveness of fair value hedges is not included in the above table. (2) Amounts include the net loss of ¥2,836 million, ¥5,230 million and ¥7,594 million on the credit derivatives hedging the credit risk of loans during the fiscal years ended March 31, 2015, 2016 and 2017, respectively.

Commitments and contingencies (

Commitments and contingencies (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Guarantor Obligations	The maximum exposure or notional amount below does not represent the expected losses from the execution of the guarantees. 2016 Maximum Amount by expiration period One year or less After one year After five years (in billions of yen) Performance guarantees 2,110 1,049 909 152 Guarantees on loans 297 117 20 160 Guarantees on securities 203 67 136 — Other guarantees 1,571 1,206 325 40 Guarantees for the repayment of trust principal 1,141 1,051 63 27 Liabilities of trust accounts 12,747 12,537 79 131 Derivative financial instruments 15,792 6,505 8,032 1,255 2017 Maximum Amount by expiration period One year or less After one year After five years (in billions of yen) Performance guarantees 2,243 1,246 828 169 Guarantees on loans 278 147 20 111 Guarantees on securities 175 37 138 — Other guarantees 1,823 1,246 513 64 Guarantees for the repayment of trust principal 730 654 52 24 Liabilities of trust accounts 15,177 14,927 82 168 Derivative financial instruments 14,415 6,066 6,603 1,746
Schedule of Off Balance Sheet Commitments and Guarantees	The table below summarizes the contractual amounts with regard to these undrawn commitments at March 31, 2016 and 2017: 2016 2017 (in billions of yen) Commitments to extend credit (Note) 75,742 76,678 Commercial letters of credit 448 522 Total 76,190 77,200 Note: Commitments to extend credit include commitments to invest in securities.
Future Minimum Lease Payments for Capitalized Leases and Rental Payments for Operating Leases	clauses of rentals. The table below shows future minimum lease payments for capitalized leases and future minimum rental payments for operating leases at March 31, 2017: Capitalized leases Operating leases (in millions of yen) Fiscal year ending March 31: 2018 11,519 52,280 2019 10,721 46,330 2020 8,697 41,157 2021 6,118 35,291 2022 3,188 30,562 2023 and thereafter 1,846 57,787 Total minimum lease/rental payments 42,089 263,407 Amount representing interest 1,142 Present value of minimum lease payments 40,947
Performance guarantees, Guarantees on loans, Guarantees on securities and Other guarantees
Schedule of Guarantor Obligations	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, 2016 and 2017: 2016 2017 (in billions of yen) Investment grade 3,160 3,477 Non-investment 1,022 1,042 Total 4,182 4,519 Note: Investment grade in the internal rating scale generally corresponds to BBB- or above in the external rating scale.

Variable interest entities an64

Variable interest entities and securitizations (Tables)	12 Months Ended
	Mar. 31, 2017
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, as of March 31, 2016 and 2017: Consolidated VIEs Significant 2016 Consolidated assets Total assets Maximum (in billions of yen) Asset-backed commercial paper/loan programs 2,092 — — Asset-backed securitizations 579 205 13 Investments in securitization products 337 445 154 Investment funds 1,660 2,422 367 Trust arrangements and other 24 — — Total 4,692 3,072 534
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, 2016 and 2017: Assets on balance sheets related to unconsolidated VIEs: 2016 2017 (in billions of yen) Trading account assets 55 85 Investments 254 254 Loans 205 237 Total 514 576 Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs: 2016 2017 (in billions of yen) Payables under securities lending transactions 27 31 Trading account liabilities 1 1 Total 28 32 Maximum exposure to loss (Note) 534 628 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

Fee and commission income (Tabl

Fee and commission income (Tables)	12 Months Ended
	Mar. 31, 2017
Other Income and Other Expense Disclosure	Details of Fee and commission income for the fiscal years ended March 31, 2015, 2016 and 2017 are as follows: 2015 2016 2017 (in millions of yen) Securities-related business 172,234 175,723 165,857 Deposits and lending business 131,491 143,763 164,573 Remittance business 110,181 109,859 108,368 Trust fees 49,827 50,496 47,379 Fees for other customer services 251,924 263,112 260,360 Total 715,657 742,953 746,537

Trading account gains and los66

Trading account gains and losses (Tables)	12 Months Ended
	Mar. 31, 2017
Gain (Loss) on Investments	Net trading gains (losses) for the fiscal years ended March 31, 2015, 2016 and 2017 are comprised of the following: 2015 2016 2017 (in millions of yen) Trading account gains (losses)—net: Trading securities 635,027 156,559 126,332 Derivative contracts: Interest rate contracts (1) 265,324 319,225 (209,361 ) Foreign exchange contracts (93,601 ) 65,101 37,129 Equity-related contracts (1) (101,988 ) 17,970 1,777 Credit-related contracts (2) (15,171 ) (1,731 ) 900 Other contracts 368 2,015 742 Total 689,959 559,139 (42,481 ) Foreign exchange gains (losses)—net (3) (34,520 ) 113,553 69,453 Net trading gains (losses) 655,439 672,692 26,972 Notes: (1) The net gain (loss) excluded from the assessment of the effectiveness of fair value hedges is included in the above table. (2) Amounts do not include the net loss of ¥2,836 million, ¥5,230 million and ¥7,594 million on the credit derivatives hedging the credit risk of loans during the fiscal years ended March 31, 2015, 2016 and 2017, respectively. The net loss is recorded in Other noninterest expenses. (3) Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments, such as translation gains and losses related to foreign currency-denominated available-for-sale

Fair value (Tables)

Fair value (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Assets and liabilities measured at fair value on a recurring basis at March 31, 2016 and 2017, including those for which the MHFG Group has elected the fair value option, are summarized below: 2016 Level 1 Level 2 Level 3 Assets/ (in billions of yen) Assets: Trading securities (1) Japanese government bonds 2,272 31 — 2,303 Japanese local government bonds — 79 — 79 U.S. Treasury bonds and federal agency securities 3,729 77 — 3,806 Other foreign government bonds 2,192 373 — 2,565 Agency mortgage-backed securities 995 563 — 1,558 Residential mortgage-backed securities — — 21 21 Commercial mortgage-backed securities — 2 2 4 Certificates of deposit and commercial paper — 881 — 881 Corporate bonds and other 9 1,693 720 2,422 Equity securities 758 62 21 841 Trading securities measured at net asset value (2) 617 Derivatives: Interest rate contracts 97 11,396 29 11,522 Foreign exchange contracts 23 3,099 8 3,130 Equity-related contracts 46 95 29 170 Credit-related contracts — 40 3 43 Other contracts — 21 38 59 Available-for-sale Japanese government bonds 15,037 726 — 15,763 Japanese local government bonds — 241 — 241 U.S. Treasury bonds and federal agency securities 438 — — 438 Other foreign government bonds 352 590 — 942 Agency mortgage-backed securities 169 780 — 949 Residential mortgage-backed securities — 87 123 210 Commercial mortgage-backed securities — — 187 187 Japanese corporate bonds and other debt securities — 1,921 174 2,095 Foreign corporate bonds and other debt securities — 739 108 847 Equity securities (marketable) 3,716 65 — 3,781 Other investments — — 42 42 Total assets measured at fair value on a recurring basis 29,833 23,561 1,505 55,516 Liabilities: Trading securities sold, not yet purchased 2,482 148 — 2,630 Derivatives: Interest rate contracts 98 11,168 3 11,269 Foreign exchange contracts 26 2,953 1 2,980 Equity-related contracts 60 56 24 140 Credit-related contracts — 33 4 37 Other contracts — 18 37 55 Long-term debt (3) — 433 623 1,056 Total liabilities measured at fair value on a recurring basis 2,666 14,809 692 18,167 2017 Level 1 Level 2 Level 3 Assets/ (in billions of yen) Assets: Trading securities (1) Japanese government bonds 1,485 23 — 1,508 Japanese local government bonds — 69 — 69 U.S. Treasury bonds and federal agency securities 2,883 80 — 2,963 Other foreign government bonds 1,127 457 — 1,584 Agency mortgage-backed securities 1,335 638 — 1,973 Residential mortgage-backed securities — — 15 15 Commercial mortgage-backed securities — 3 — 3 Certificates of deposit and commercial paper — 554 — 554 Corporate bonds and other 3 1,449 1,052 2,504 Equity securities 1,661 20 23 1,704 Trading securities measured at net asset value (2) 678 Derivatives: Interest rate contracts 37 8,442 27 8,506 Foreign exchange contracts 28 2,709 8 2,745 Equity-related contracts 31 89 14 134 Credit-related contracts — 33 2 35 Other contracts 1 11 11 23 Available-for-sale Japanese government bonds 9,543 720 — 10,263 Japanese local government bonds — 284 — 284 U.S. Treasury bonds and federal agency securities 1,144 — — 1,144 Other foreign government bonds 346 589 — 935 Agency mortgage-backed securities 134 709 — 843 Residential mortgage-backed securities — 67 77 144 Commercial mortgage-backed securities — — 224 224 Japanese corporate bonds and other debt securities — 1,834 174 2,008 Foreign corporate bonds and other debt securities — 801 110 911 Equity securities (marketable) 3,717 84 — 3,801 Other investments — — 37 37 Total assets measured at fair value on a recurring basis 23,475 19,665 1,774 45,592 Liabilities: Trading securities sold, not yet purchased 1,993 228 — 2,221 Derivatives: Interest rate contracts 46 8,426 1 8,473 Foreign exchange contracts 20 2,591 — 2,611 Equity-related contracts 129 61 39 229 Credit-related contracts — 34 2 36 Other contracts 1 10 11 22 Long-term debt (3) — 903 593 1,496 Total liabilities measured at fair value on a recurring basis 2,189 12,253 646 15,088 Notes: (1) Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option. (2) 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, 2016 and 2017 were ¥30 billion and ¥33 billion, respectively. (3) Amounts represent items for which the Group elected the fair value option.
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation	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, 2016 and 2017: 2016 April 1, Gains Gains Transfers Transfers Purchases Sales Issuances Settlements March 31, 2016 Change in (losses) (6) (in billions of yen) Assets: Trading securities: Other foreign government bonds — — (2) — — — 1 (1 ) — — — — Residential mortgage-backed securities 29 — (2) — — — — — — (8 ) 21 — Commercial mortgage-backed securities 4 — (2) — — — — — — (2 ) 2 — Corporate bonds and other 639 (43 ) (2) — 25 (34 ) 452 (192 ) — (127 ) 720 (38 ) Equity securities 23 (3 ) (2) — — — 1 — — — 21 (1 ) Derivatives, net (1) Interest rate contracts 18 (1 ) (2) — — — — — — 9 26 11 Foreign exchange contracts 8 (1 ) (2) — — — — — — — 7 (2 ) Equity-related contracts (14 ) 22 (2) — — — — — — (3 ) 5 14 Credit-related contracts (1 ) — (2) — — — — — — — (1 ) — Other contracts — 1 (2) — — — — — — — 1 1 Available-for-sale Residential mortgage-backed securities 166 — (3) — (4) — — — (4 ) — (39 ) 123 — Commercial mortgage-backed securities 169 — (3) — (4) — — 102 (62 ) — (22 ) 187 — Japanese corporate bonds and other debt securities 155 (2 ) (3) — (4) — — 67 (3 ) — (43 ) 174 (4 ) Foreign corporate bonds and other debt securities 85 2 (3) (5 ) (4) 23 — 41 — — (38 ) 108 — Other investments 53 7 (3) — — — 5 (20 ) — (3 ) 42 (7 ) Liabilities: Trading securities sold, not yet purchased — — (2) — — — (5 ) 5 — — — — Long-term debt 587 18 (5) — 8 — (1 ) — 305 (258 ) 623 19 2017 April 1, Gains Gains Transfers Transfers Purchases Sales Issuances Settlements March 31, 2017 Change in (losses) (6) (in billions of yen) Assets: Trading securities: Residential mortgage-backed securities 21 (1 ) (2) — — — — — — (5 ) 15 (1 ) Commercial mortgage-backed securities 2 — (2) — — — — — — (2 ) — — Corporate bonds and other 720 12 (2) — 296 (39 ) 875 (555 ) — (257 ) 1,052 19 Equity securities 21 1 (2) — — — 3 (2 ) — — 23 — Derivatives, net (1) Interest rate contracts 26 (2 ) (2) — — — — — — 2 26 2 Foreign exchange contracts 7 7 (2) — — — — — — (6 ) 8 1 Equity-related contracts 5 (31 ) (2) — — — — — — 1 (25 ) (35 ) Credit-related contracts (1 ) 1 (2) — — — — — — — — — Other contracts 1 — (2) — — — — — — (1 ) — — Available-for-sale Residential mortgage-backed securities 123 — (3) (1 ) (4) — — — (7 ) — (38 ) 77 — Commercial mortgage-backed securities 187 — (3) 1 (4) — — 63 (12 ) — (15 ) 224 — Japanese corporate bonds and other debt securities 174 (1 ) (3) 43 (4) — — 10 (19 ) — (33 ) 174 — Foreign corporate bonds and other debt securities 108 1 (3) (1 ) (4) — (2 ) 10 — — (6 ) 110 — Other investments 42 — (3) — — — 12 (3 ) — (14 ) 37 — Liabilities: Trading securities sold, not yet purchased — — (2) — 1 — (54 ) 53 — — — — Long-term debt 623 20 (5) — 21 (12 ) (2 ) 1 278 (296 ) 593 18 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, 2016 and 2017.
Quantitative Information About Level Three 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, 2016 and 2017: 2016 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 144 Discounted cash flow Prepayment rate 3%–19% 7% Price-based Default rate 0%–2% 0% Recovery rate 100%–100% 100% Discount margin 13bps–180bps 60bps Commercial mortgage-backed securities 189 Discounted cash flow Price-based Discount margin 6bps–580bps 37bps Corporate bonds and other debt securities 1,002 Discounted cash flow Prepayment rate (1) 0%–21% 19% Price-based Default rate (1) 0%–2% 2% Recovery rate (1) 60%–69% 68% Discount margin (1) 11bps–1,115bps 151bps Discount margin (2) 10bps–3,850bps 454bps Derivatives, net: Interest rate contracts 26 Internal valuation model (3) IR – IR correlation 32%–100% Default rate (4) 0%–63% Foreign exchange contracts 7 Internal valuation model (3) FX – IR correlation 5%–50% FX – FX correlation 54%–54% Default rate (4) 0%–63% Equity-related contracts 5 Internal valuation model (3) Equity – IR correlation 30%–30% Equity – FX correlation 55%–55% Equity volatility 10%–40% Credit-related contracts (1) Internal valuation model (3) Default rate 0%–42% Credit correlation 29%–100% Long-term debt 623 Internal valuation model (3) IR – IR correlation 32%–100% FX – IR correlation 5%–50% FX – FX correlation 54%–54% Equity – IR correlation 30%–30% Equity – FX correlation 55%–55% Equity correlation 18%–100% Equity volatility 14%–39% Default rate 0%–5% Credit correlation 28%–100% 2017 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 92 Discounted cash flow Prepayment rate 0%–18% 7% Price-based Default rate 0%–1% 0% Recovery rate 100%–100% 100% Discount margin 15bps–170bps 55bps Commercial mortgage-backed securities 224 Discounted cash flow Price-based Discount margin 4bps–205bps 28bps Corporate bonds and other debt securities 1,336 Discounted cash flow Prepayment rate (1) 16%–30% 29% Price-based Default rate (1) 1%–2% 2% Recovery rate (1) 60%–68% 68% Discount margin (1) 8bps–1,181bps 131bps Discount margin (2) 10bps–939bps 359bps Derivatives, net: Interest rate contracts 26 Internal valuation model (3) IR – IR correlation 23%–100% Default rate (4) 0%–63% Foreign exchange contracts 8 Internal valuation model (3) FX – IR correlation 5%–52% FX – FX correlation 55%–55% Default rate (4) 0%–63% Equity-related contracts (25) Internal valuation model (3) Equity – IR correlation 25%–25% Equity – FX correlation 55%–55% Equity volatility 6%–59% Credit-related contracts — Internal valuation model (3) Default rate 0%–5% Credit correlation 30%–100% Long-term debt 593 Internal valuation model (3) IR – IR correlation 23%–100% FX – IR correlation 5%–52% FX – FX correlation 55%–55% Equity – IR correlation 25%–25% Equity – FX correlation 55%–55% Equity correlation 20%–100% Equity volatility 5%–40% Default rate 0%–3% Credit correlation 33%–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.
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis	The following table shows the fair value hierarchy for these items as of March 31, 2016 and 2017: 2016 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 124 — — 124 197 Loans held-for-sale 13 — 7 6 14 Other investments 1 — — 1 2 Premises and equipment—net — — — — 1 Goodwill — — — — 6 Total assets measured at fair value on a nonrecurring basis 138 — 7 131 220 2017 Total Level 1 Level 2 Level 3 Aggregate cost (in billions of yen) Assets: Loans 124 — — 124 194 Loans held-for-sale 7 — 7 — 8 Other investments 7 6 — 1 11 Premises and equipment—net 7 — 6 1 11 Total assets measured at fair value on a nonrecurring basis 145 6 13 126 224
Fair Value, by Balance Sheet Grouping	The following table shows the carrying amounts and fair values at March 31, 2016 and 2017, 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 840, “Leases” (“ASC 840”) : 2016 Carrying Estimated fair value Total Level 1 Level 2 Level 3 (in billions of yen) Financial assets: Cash and due from banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions 48,757 48,757 923 47,834 — Investments 4,819 4,873 4,873 — — Loans, net of allowance for loan losses (Note) 77,040 78,241 — — 78,241 Financial liabilities: Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions 39,908 39,908 17,223 22,685 — Interest-bearing deposits 100,228 100,234 46,207 54,027 — Due to trust accounts 4,467 4,467 — 4,467 — Other short-term borrowings 2,080 2,080 — 2,080 — Long-term debt 13,691 13,863 — 12,969 894 2017 Carrying Estimated fair value Total Level 1 Level 2 Level 3 (in billions of yen) Financial assets: Cash and due from banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions 60,943 60,943 1,063 59,880 — Investments 3,817 3,846 3,846 — — Loans, net of allowance for loan losses (Note) 81,662 82,696 — — 82,696 Financial liabilities: Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions 42,205 42,205 20,544 21,661 — Interest-bearing deposits 110,125 110,124 56,738 53,386 — Due to trust accounts 4,123 4,123 — 4,123 — Other short-term borrowings 1,477 1,477 — 1,477 — Long-term debt 13,009 13,078 — 12,120 958 Note: Loans, net of allowance for loan losses include items measured at fair value on a nonrecurring basis.

Offsetting of financial asset68

Offsetting of financial assets and financial liabilities (Tables)	12 Months Ended
	Mar. 31, 2017
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, 2016 and 2017. 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 (3) Gross amounts recognized Gross amounts offset on the Net amounts presented on the (2) Financial instruments (4) Cash collateral Net (in billions of yen) 2016 Assets (1) Derivatives 14,130 — 14,130 (12,167 ) (599 ) 1,364 Receivables under resale agreements 7,490 — 7,490 (7,461 ) — 29 Receivables under securities borrowing transactions 3,327 — 3,327 (3,318 ) — 9 Total 24,947 — 24,947 (22,946 ) (599 ) 1,402 Liabilities (1) Derivatives 13,652 — 13,652 (12,043 ) (748 ) 861 Payables under repurchase agreements 16,507 — 16,507 (16,464 ) — 43 Payables under securities lending transactions 2,538 — 2,538 (2,531 ) — 7 Total 32,697 — 32,697 (31,038 ) (748 ) 911 2017 Assets (1) Derivatives 10,608 — 10,608 (8,966 ) (620 ) 1,022 Receivables under resale agreements 8,698 — 8,698 (8,662 ) — 36 Receivables under securities borrowing transactions 3,127 — 3,127 (3,116 ) — 11 Total 22,433 — 22,433 (20,744 ) (620 ) 1,069 Liabilities (1) Derivatives 10,405 — 10,405 (8,866 ) (901 ) 638 Payables under repurchase agreements 17,446 — 17,446 (17,391 ) — 55 Payables under securities lending transactions 1,458 — 1,458 (1,455 ) — 3 Total 29,309 — 29,309 (27,712 ) (901 ) 696 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 sec69

Repurchase agreements and securities lending transactions accounted for as secured borrowings (Tables)	12 Months Ended
	Mar. 31, 2017
Gross Amounts of Liabilities Associated with Repurchase Agreements and Securities Lending Transactions, 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, 2016 and 2017: Overnight and Up to 30 days 31-90 days Greater than Total (in billions of yen) 2016 Repurchase agreements 6,289 6,125 3,582 837 16,833 Securities lending transactions 1,909 700 — 236 2,845 Total 8,198 6,825 3,582 1,073 19,678 2017 Repurchase agreements 249 12,700 3,897 1,124 17,970 Securities lending transactions 320 1,359 — 240 1,919 Total 569 14,059 3,897 1,364 19,889
Gross Amounts of Liabilities Associated with Repurchase Agreements and Securities Lending Transactions 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, 2016 and 2017: Repurchase Securities lending (in billions of yen) 2016 Japanese government bonds and Japanese local government bonds 532 1,891 Foreign government bonds and foreign agency mortgage-backed securities 15,781 700 Commercial paper and corporate bonds 221 27 Equity securities 141 185 Other 158 42 Total (Note) 16,833 2,845 2017 Japanese government bonds and Japanese local government bonds 1,127 1,152 Foreign government bonds and foreign agency mortgage-backed securities 15,782 375 Commercial paper and corporate bonds 294 47 Equity securities 578 320 Other 189 25 Total (Note) 17,970 1,919 Note: Amounts exceeded the gross amounts recognized in Note 29 “Offsetting of financial assets and financial liabilities” by ¥633 billion and ¥985 billion, at March 31, 2016 and 2017, 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

Business segment information (T

Business segment information (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Segment Reporting Information, by Segment	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 each business segment’s net business profits with income before income tax expense under U.S. GAAP. Management does not use information on business segment’s assets to allocate resources and assess performance and has not prepared information on the segment’s assets. Accordingly, information on the segment’s assets is not available. MHFG (Consolidated) 2016 (1) Retail & Corporate & Global Global Asset Others (3) Total (in billions of yen) Gross profits 676.4 434.9 403.8 577.7 52.1 76.7 2,221.6 General and administrative expenses 661.2 183.2 232.7 178.9 30.1 58.9 1,345.0 Others — — — — — (23.7 ) (23.7 ) Net business profits (losses) (2) 15.2 251.7 171.1 398.8 22.0 (5.9 ) 852.9 MHFG (Consolidated) 2017 Retail & Corporate & Global Global Asset Others (3) Total (in billions of yen) Gross profits 646.1 445.1 386.5 539.4 49.6 26.0 2,092.7 General and administrative expenses 678.3 186.7 237.8 200.9 29.3 87.5 1,420.5 Others — — — — — (8.8 ) (8.8 ) Net business profits (losses) (2) (32.2 ) 258.4 148.7 338.5 20.3 (70.3 ) 663.4 Notes: (1) Following the introduction of an in-house (2) Net business profits is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (or the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income) less general and administrative expenses. Measurement of net business profits is required for regulatory reporting to the Financial Services Agency. (3) “Others” includes items which should be eliminated as internal transactions between each segment on a consolidated basis. Before the introduction of the in-house 2015 (1)(2) MHBK (Consolidated) MHTB (Consolidated) MHSC (Consolidated) Others MHFG MHBK (Non-consolidated) Others Total Total Personal Retail Banking Corporate (Large Corporate Financial Inter- national Trading and others (h) (i) (j) (k) Total (in billions of yen) Gross profits: Net interest income 1,087.3 934.9 213.4 77.6 179.5 99.6 33.3 147.1 184.4 152.4 39.4 1.8 0.9 1,129.4 Net noninterest income 598.4 560.6 48.7 53.7 128.0 79.8 27.4 164.9 58.1 37.8 122.6 335.8 61.5 1,118.3 Total 1,685.7 1,495.5 262.1 131.3 307.5 179.4 60.7 312.0 242.5 190.2 162.0 337.6 62.4 2,247.7 General and administrative expenses 904.7 833.7 233.5 118.4 94.4 76.5 30.3 92.6 188.0 71.0 94.5 268.0 54.0 1,321.2 Others (43.2 ) — — — — — — — — (43.2 ) (3.7 ) — (2.7 ) (49.6 ) Net business profits (3) 737.8 661.8 28.6 12.9 213.1 102.9 30.4 219.4 54.5 76.0 63.8 69.6 5.7 876.9 2016 (2) MHBK (Consolidated) MHTB (Consolidated) MHSC (Consolidated) Others MHFG (Consolidated) MHBK (Non-consolidated) Others Total Total Personal Retail Banking Corporate (Large Corporate Financial Inter- national Trading and others (h) (i) (j) (k) Total (in billions of yen) Gross profits: Net interest income 959.4 830.1 214.8 75.7 173.0 97.5 32.5 175.5 61.1 129.3 36.1 5.4 2.8 1,003.7 Net noninterest income 675.3 633.7 45.0 53.1 143.7 77.5 31.8 185.1 97.5 41.6 130.7 343.8 68.1 1,217.9 Total 1,634.7 1,463.8 259.8 128.8 316.7 175.0 64.3 360.6 158.6 170.9 166.8 349.2 70.9 2,221.6 General and administrative expenses 903.3 833.3 234.4 118.6 91.9 75.2 29.8 122.1 161.3 70.0 99.1 279.3 63.3 1,345.0 Others (22.1 ) — — — — — — — — (22.1 ) (4.2 ) — 2.5 (23.8 ) Net business profits (losses) (3) 709.3 630.5 25.4 10.2 224.8 99.8 34.5 238.5 (2.7 ) 78.8 63.5 69.9 10.1 852.8 2017 (2)(4) MHBK (Consolidated) MHTB (Consolidated) MHSC (Consolidated) Others MHFG (Consolidated) MHBK (Non-consolidated) Others Total (a)-(g) Total (h) (i) (j) (k) Total (in billions of yen) Gross profits: Net interest income (expense) 836.5 719.8 116.7 30.2 (1.5 ) 2.6 867.8 Net noninterest income 686.7 600.6 86.1 121.8 333.1 83.3 1,224.9 Total 1,523.2 1,320.4 202.8 152.0 331.6 85.9 2,092.7 General and administrative expenses 982.7 866.6 116.1 101.6 257.5 78.7 1,420.5 Others (8.7 ) — (8.7 ) (5.2 ) 0.1 5.0 (8.8 ) Net business profits (3) 531.8 453.8 78.0 45.2 74.2 12.2 663.4 Notes: (1) Beginning on April 1, 2015, new allocation methods have been applied to the calculation of “Gross profits” and “General and administrative expenses” for reportable segments of MHBK. Figures for the fiscal year ended March 31, 2015 have been restated for the new allocation methods. (2) “Others (h)” and “Others (k)” include the elimination of transactions between consolidated subsidiaries. (3) Net business profits is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (or the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income) less general and administrative expenses. Measurement of net business profits is required for regulatory reporting to the Financial Services Agency. (4) Segment information based on the relevant principal consolidated subsidiaries for the fiscal year ended March 31, 2017 is presented for comparability purposes. Due to system limitations, it is impracticable to present the details of MHBK (Non-consolidated).
Reconciliation of Operating Profit (Loss) from Segments to Consolidated	consolidated statements of income. A reconciliation of total net business profits under the internal management reporting systems for the fiscal years ended March 31, 2015, 2016 and 2017 presented above to income before income tax expense shown on the consolidated statements of income is as follows: 2015 2016 2017 (in billions of yen) Net business profits 876.9 852.8 663.4 U.S. GAAP adjustments 230.8 201.3 (387.8 ) (Provision) credit for loan losses 60.2 (34.6 ) (37.7 ) Net gains (losses) related to equity investments 160.1 188.4 259.6 Non-recurring (8.0 ) (3.9 ) (8.8 ) Gains on disposal of premises and equipment 2.8 10.2 5.6 (Provision) credit for losses on off-balance-sheet 2.8 16.4 (19.5 ) Others—net (57.9 ) (34.0 ) 5.6 Income before income tax expense 1,267.7 1,196.6 480.4

Foreign activities (Tables)

Foreign activities (Tables)	12 Months Ended
	Mar. 31, 2017
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas	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 Others Europe Asia/Oceania and others Total (in billions of yen) Fiscal year ended March 31, 2015: Total revenue (1) 2,396.9 324.1 102.4 211.8 223.7 3,258.9 Total expenses (2) 1,459.9 210.8 24.3 133.8 162.4 1,991.2 Income before income tax expense 937.0 113.3 78.1 78.0 61.3 1,267.7 Net income 565.6 79.7 76.2 74.3 34.4 830.2 Total assets at end of fiscal year 127,468.2 31,074.9 4,871.0 10,880.6 15,819.7 190,114.4 Fiscal year ended March 31, 2016: Total revenue (1) 2,288.5 434.4 45.7 187.5 428.0 3,384.1 Total expenses (2) 1,534.2 282.6 28.7 126.2 215.8 2,187.5 Income before income tax expense 754.3 151.8 17.0 61.3 212.2 1,196.6 Net income 464.7 136.9 15.4 51.1 182.0 850.1 Total assets at end of fiscal year 133,157.1 28,985.3 4,227.5 11,616.9 15,823.4 193,810.2 Fiscal year ended March 31, 2017: Total revenue (1) 1,748.3 500.3 70.3 190.7 367.5 2,877.1 Total expenses (2) 1,712.3 303.2 29.1 136.2 215.9 2,396.7 Income before income tax expense 36.0 197.1 41.2 54.5 151.6 480.4 Net income 5.7 167.6 38.8 39.5 137.5 389.1 Total assets at end of fiscal year 138,832.3 30,262.0 4,203.3 10,629.1 16,529.6 200,456.3 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.,72

Mizuho Financial Group, Inc., parent company (Tables)	12 Months Ended
	Mar. 31, 2017
Condensed Financial Information of Parent Company Only, Statements of Financial Condition	Condensed balance sheets 2016 2017 (in millions of yen) Assets: Cash and due from banks 137 15,912 Interest-bearing deposits in other banks 16,305 4,278 Investments in subsidiaries and affiliated companies 8,840,003 8,993,388 Long-term loans receivable from subsidiaries 624,518 2,697,250 Other 400,590 477,375 Total 9,881,553 12,188,203 Liabilities and shareholders’ equity: Short-term borrowings 1,186,345 1,156,100 Long-term debt 584,518 2,632,250 Other liabilities 96,139 138,496 Shareholders’ equity 8,014,551 8,261,357 Total 9,881,553 12,188,203
Condensed Financial Information of Parent Company Only, Statement of Income	Condensed statements of income 2015 2016 2017 (in millions of yen) Income: Dividends from subsidiaries and affiliated companies: Banking subsidiaries 316,035 272,070 300,530 Non-banking 28,633 20,814 27,618 Management fees from subsidiaries 32,163 39,267 48,594 Interest Income on Loans and Discounts 799 9,630 39,359 Other income 37,308 1,855 21,054 Total 414,938 343,636 437,155 Expenses: Operating expenses 26,855 31,063 38,927 Interest expense 8,937 11,914 38,759 Bond issuance cost 865 3,230 9,835 Other expense 1,828 5,973 7,708 Total 38,485 52,180 95,229 Equity in undistributed net income of subsidiaries 427,037 559,553 21,251 Income before income tax expense 803,490 851,009 363,177 Income tax expense 442 517 737 Net income 803,048 850,492 362,440
Condensed Financial Information of Parent Company Only, Statements of Cash Flows	Condensed statements of cash flows 2015 2016 2017 (in millions of yen) Cash flows from operating activities: Net income 803,048 850,492 362,440 Adjustments and other (460,230 ) (546,946 ) (40,595 ) Net cash provided by operating activities 342,818 303,546 321,845 Cash flows from investing activities: Net change in loans (150,000 ) (479,948 ) (2,022,860 ) Purchases of premises and equipment (159,670 ) (165 ) (40,362 ) Payments for purchases of securities of subsidiaries — (2,249 ) (65,269 ) Proceeds from withdrawal of securities of subsidiaries — — 13,359 Net change in other investing activities 3,294 1,872 6,691 Net cash used in investing activities (306,376 ) (480,490 ) (2,108,441 ) Cash flows from financing activities: Net change in short-term borrowings 130,000 (10,000 ) (30,000 ) Proceeds from issuance of long-term debt 150,000 479,948 2,022,860 Repayment of long-term debt (141,200 ) (98,800 ) — Proceeds from issuance of common stock 6 5 6 Purchases of treasury stock (12 ) (13 ) (1,435 ) Dividends paid (176,186 ) (195,283 ) (190,031 ) Net change in other financing activities 1,006 1,001 971 Net cash provided by (used in) financing activities (36,386 ) 176,858 1,802,371 Net increase (decrease) in cash and due from banks 56 (86 ) 15,775 Cash and due from banks at beginning of fiscal year 167 223 137 Cash and due from banks at end of fiscal year 223 137 15,912

Basis of Presentation and Sum73

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Mar. 31, 2017
Minimum
Significant Accounting Policies [Line Items]
Period in which obligors generally determined to be substantially bankrupt, past due (in months)	6 months
Minimum | Impaired loans
Significant Accounting Policies [Line Items]
Number of days past due	90 days
Software and Software Development Costs | Minimum
Significant Accounting Policies [Line Items]
Estimated useful life	5 years
Software and Software Development Costs | Maximum
Significant Accounting Policies [Line Items]
Estimated useful life	10 years
Shinko Securities Company Limited | Customer relationships
Significant Accounting Policies [Line Items]
Weighted-average amortization period	16 years
Asset Management Company | Customer relationships
Significant Accounting Policies [Line Items]
Weighted-average amortization period	16 years 10 months 25 days

Basis of Presentation and Sum74

Basis of Presentation and Summary of Significant Accounting Policies (Useful Lives of Premises and Equipment) (Detail)	12 Months Ended
	Mar. 31, 2017
Buildings | Minimum
Property, Plant, and Equipment Disclosure [Line Items]
Years	3 years
Buildings | Maximum
Property, Plant, and Equipment Disclosure [Line Items]
Years	50 years
Equipment and furniture | Minimum
Property, Plant, and Equipment Disclosure [Line Items]
Years	2 years
Equipment and furniture | Maximum
Property, Plant, and Equipment Disclosure [Line Items]
Years	20 years
Leasehold improvements | Minimum
Property, Plant, and Equipment Disclosure [Line Items]
Years	3 years
Leasehold improvements | Maximum
Property, Plant, and Equipment Disclosure [Line Items]
Years	50 years

Recently Issued Accounting Pr75

Recently Issued Accounting Pronouncements - Additional Information (Detail) - ASU No. 2015-02 ¥ in Millions	Mar. 31, 2017JPY (¥)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principles, net of tax	¥ (329)
Accumulated Other Comprehensive Income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting principles, net of tax	¥ 330

Business Combination - Addition

Business Combination - Additional Information (Detail) ¥ in Millions	Oct. 01, 2016JPY (¥)shares
MHAM
Business Acquisition [Line Items]
Interests exchanged	30.00%
Remeasurement gain recognized	¥ 23,829
Percentage of equity held by acquirer immediately before acquisition	30.00%
DIAM
Business Acquisition [Line Items]
Fair value of MHFG's equity interests in DIAM held before the business combination	¥ 72,106
Common shares of MHAM | shares	1,038,408
Fair value of total consideration transferred	¥ 28,842
Fair value, noncontrolling interest	43,264
Remeasurement gain recognized	¥ 56,226
Asset Management One
Business Acquisition [Line Items]
Percentage of shareholding ratio based on voting rights	51.00%
Percentage of shareholding ratio based on economic interests	70.00%

Business Combination - (Summary

Business Combination - (Summary of Consideration Paid for DIAM) (Detail) - JPY (¥) ¥ in Millions		Oct. 01, 2016	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Recognized amounts of identifiable liabilities assumed:
Goodwill			¥ 95,176	¥ 19,097	¥ 11,703	¥ 11,549
DIAM
Consideration:
Equity instruments (1,038,408 common shares of MHAM)		¥ 28,842
Fair value of total consideration transferred		28,842
Fair value of equity interests in DIAM held by MHFG before the business combination		72,106
Business Combination, Consideration Transferred, Including Equity Interest in Acquiree Held Prior to Combination, Total		100,948
Recognized amounts of identifiable assets acquired:
Cash and due from banks		831
Interest-bearing deposits in other banks		12,873
Trading account assets		266
Investments		12,234
Premises and equipment-net		3,546
Accrued income		7,882
Intangible assets	[1]	53,037
Deferred tax assets		1,003
Other assets		2,208
Recognized amounts of identifiable liabilities assumed:
Trading account liabilities		304
Income taxes payable		918
Deferred taxes liabilities		16,238
Accrued expenses		5,392
Other liabilities		3,041
Total identifiable net assets		67,987
Goodwill		76,225
Noncontrolling interest in DIAM		43,264
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest		¥ 100,948
[1]	Note: Amount represents customer relationships subject to amortization, of which the weighted-average amortization period is 16.9 years.

Business Combination - (Summa78

Business Combination - (Summary of Consideration Paid for DIAM) (Parenthetical) (Detail) - DIAM	Oct. 01, 2016shares
Business Acquisition [Line Items]
Common shares of MHAM	1,038,408
Customer relationships
Business Acquisition [Line Items]
Weighted-average amortization period	16 years 10 months 25 days

Investments (Amortized Cost Gro

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, 2017	Mar. 31, 2016
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		¥ 18,213,761	¥ 23,180,206
Gross unrealized gains, available-for-sale securities		2,376,615	2,282,634
Gross unrealized losses, available-for-sale securities		33,258	10,315
Fair value, available-for-sale securities		20,557,118	25,452,525
Amortized cost, held-to-maturity securities		3,817,360	4,818,961
Gross unrealized gains, held-to-maturity securities		37,289	60,514
Gross unrealized losses, held-to-maturity securities		7,931	6,266
Fair value, held-to-maturity securities		3,846,718	4,873,209
Debt securities | Agency mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities	[1]	832,738	920,375
Gross unrealized gains, available-for-sale securities	[1]	15,500	29,804
Gross unrealized losses, available-for-sale securities	[1],[2]	5,441	1,293
Fair value, available-for-sale securities	[1]	842,797	948,886
Amortized cost, held-to-maturity securities	[3]	757,384	1,058,929
Gross unrealized gains, held-to-maturity securities	[3]	121	3,894
Gross unrealized losses, held-to-maturity securities	[3]	7,931	6,266
Fair value, held-to-maturity securities	[3]	749,574	1,056,557
Debt securities | Japanese government bonds
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		10,256,512	15,672,171
Gross unrealized gains, available-for-sale securities		22,782	91,420
Gross unrealized losses, available-for-sale securities		16,408	1,015
Fair value, available-for-sale securities		10,262,886	15,762,576
Amortized cost, held-to-maturity securities		3,059,976	3,760,032
Gross unrealized gains, held-to-maturity securities		37,168	56,620
Fair value, held-to-maturity securities		3,097,144	3,816,652
Debt securities | Japanese local government bonds
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		279,864	234,587
Gross unrealized gains, available-for-sale securities		4,841	6,097
Gross unrealized losses, available-for-sale securities		233	3
Fair value, available-for-sale securities		284,472	240,681
Debt securities | U.S. Treasury bonds and federal agency securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		1,148,389	436,792
Gross unrealized gains, available-for-sale securities		10	1,720
Gross unrealized losses, available-for-sale securities		4,578	32
Fair value, available-for-sale securities		1,143,821	438,480
Debt securities | Other foreign government bonds
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		933,942	939,808
Gross unrealized gains, available-for-sale securities		1,246	2,740
Gross unrealized losses, available-for-sale securities		236	153
Fair value, available-for-sale securities		934,952	942,395
Debt securities | Residential mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		142,879	206,882
Gross unrealized gains, available-for-sale securities		1,838	4,254
Gross unrealized losses, available-for-sale securities		558	878
Fair value, available-for-sale securities		144,159	210,258
Debt securities | Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		223,105	186,525
Gross unrealized gains, available-for-sale securities		1,092	788
Gross unrealized losses, available-for-sale securities		282	523
Fair value, available-for-sale securities		223,915	186,790
Debt securities | Japanese corporate bonds and other debt securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities	[4]	1,958,472	2,079,599
Gross unrealized gains, available-for-sale securities	[4]	52,046	15,688
Gross unrealized losses, available-for-sale securities	[4]	2,286	420
Fair value, available-for-sale securities	[4]	2,008,232	2,094,867
Debt securities | Foreign corporate bonds and other debt securities
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities	[5]	909,052	839,981
Gross unrealized gains, available-for-sale securities	[5]	3,377	8,744
Gross unrealized losses, available-for-sale securities	[5]	1,643	1,421
Fair value, available-for-sale securities	[5]	910,786	847,304
Equity securities (marketable)
Schedule of Investments [Line Items]
Amortized cost, available-for-sale securities		1,528,808	1,663,486
Gross unrealized gains, available-for-sale securities		2,273,883	2,121,379
Gross unrealized losses, available-for-sale securities		1,593	4,577
Fair value, available-for-sale securities		¥ 3,801,098	¥ 3,780,288
[1]	Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥168,604 million and ¥780,282 million, respectively, at March 31, 2016, and ¥134,240 million and ¥708,557 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Government National Mortgage Association ("Ginnie Mae") securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.
[2]	Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥69,805 million and ¥4,307 million, respectively, at March 31, 2016, and ¥134,118 million and ¥104,270 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.
[3]	All Agency mortgage-backed securities presented in the above table are Ginnie Mae securities.
[4]	Other debt securities presented in the above table primarily consist of certificates of deposit ("CDs") and asset-backed securities ("ABS"), of which the total fair values were ¥158,446 million at March 31, 2016, and ¥155,138 million at March 31, 2017.
[5]	Other debt securities presented in the above table primarily consist of CDs, ABS, and collateralized loan obligations ("CLO"), of which the total fair values were ¥201,952 million at March 31, 2016, and ¥258,059 million at March 31, 2017.

Investments (Amortized Cost G80

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, 2017	Mar. 31, 2016
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		¥ 20,557,118	¥ 25,452,525
Agency mortgage-backed securities | Debt securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities	[1]	842,797	948,886
Certificates of deposit ("CDs") and Asset-Backed Securities ("ABS") | Japanese government and corporate debt securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		155,138	158,446
CDs, ABS, and collateral loan obligations ("CLO") | Foreign government and corporate debt securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		258,059	201,952
U.S. agency securities | Agency mortgage-backed securities | Debt securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		134,240	168,604
Japanese agency securities | Agency mortgage-backed securities | Debt securities
Schedule of Investments [Line Items]
Fair value, available-for-sale securities		¥ 708,557	¥ 780,282
[1]	Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥168,604 million and ¥780,282 million, respectively, at March 31, 2016, and ¥134,240 million and ¥708,557 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Government National Mortgage Association ("Ginnie Mae") securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.

Investments (Amortized Cost and

Investments (Amortized Cost and Fair Value of Available-for-sale and Held-to-maturity Debt Securities by Contractual Maturity) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		¥ 5,941,730
Due after one year through five years, amortized cost		7,193,285
Due after five years through ten years,amortized cost		2,381,395
Due after ten years, amortized cost		1,168,543
Total		16,684,953
Due in one year or less, amortized cost		1,100,032
Due after one year through five years, amortized cost		1,480,073
Due after five years through ten years, amortized cost		479,871
Due after ten years, amortized cost		757,384
Amortized cost, held-to-maturity securities		3,817,360	¥ 4,818,961
Due in one year or less, fair value		5,945,667
Due after one year through five years, fair value		7,209,817
Due after five years through ten years, fair value		2,376,092
Due after ten years, fair value		1,224,444
Total		16,756,020
Due in one year or less, fair value		1,102,730
Due after one year through five years, fair value		1,491,570
Due after five years through ten years, fair value		502,844
Due after ten years, fair value		749,574
Total		3,846,718	4,873,209
Debt securities | Japanese government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		3,147,992
Due after one year through five years, amortized cost		5,538,724
Due after five years through ten years,amortized cost		1,569,796
Total		10,256,512
Due in one year or less, amortized cost		1,100,032
Due after one year through five years, amortized cost		1,480,073
Due after five years through ten years, amortized cost		479,871
Amortized cost, held-to-maturity securities		3,059,976	3,760,032
Due in one year or less, fair value		3,151,367
Due after one year through five years, fair value		5,549,293
Due after five years through ten years, fair value		1,562,226
Total		10,262,886
Due in one year or less, fair value		1,102,730
Due after one year through five years, fair value		1,491,570
Due after five years through ten years, fair value		502,844
Total		3,097,144	3,816,652
Debt securities | Agency mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due after ten years, amortized cost		832,738
Total		832,738
Due after ten years, amortized cost		757,384
Amortized cost, held-to-maturity securities	[1]	757,384	1,058,929
Due after ten years, fair value		842,797
Total		842,797
Due after ten years, fair value		749,574
Total	[1]	749,574	¥ 1,056,557
Debt securities | Japanese local government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		41,307
Due after one year through five years, amortized cost		101,307
Due after five years through ten years,amortized cost		136,701
Due after ten years, amortized cost		549
Total		279,864
Due in one year or less, fair value		41,366
Due after one year through five years, fair value		102,326
Due after five years through ten years, fair value		140,138
Due after ten years, fair value		642
Total		284,472
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		1,065,881
Due after five years through ten years,amortized cost		82,508
Total		1,148,389
Due in one year or less, fair value		1,065,415
Due after five years through ten years, fair value		78,406
Total		1,143,821
Debt securities | Other foreign government bonds
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		757,093
Due after one year through five years, amortized cost		170,836
Due after five years through ten years,amortized cost		6,013
Total		933,942
Due in one year or less, fair value		757,094
Due after one year through five years, fair value		171,662
Due after five years through ten years, fair value		6,196
Total		934,952
Debt securities | Residential mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due after ten years, amortized cost		142,879
Total		142,879
Due after ten years, fair value		144,159
Total		144,159
Debt securities | Commercial mortgage-backed securities
Investments Classified by Contractual Maturity Date [Line Items]
Due in one year or less, amortized cost		7,000
Due after one year through five years, amortized cost		116,633
Due after five years through ten years,amortized cost		99,472
Total		223,105
Due in one year or less, fair value		7,008
Due after one year through five years, fair value		116,641
Due after five years through ten years, fair value		100,266
Total		223,915
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		471,592
Due after one year through five years, amortized cost		866,455
Due after five years through ten years,amortized cost		431,097
Due after ten years, amortized cost		189,328
Total		1,958,472
Due in one year or less, fair value		472,047
Due after one year through five years, fair value		869,226
Due after five years through ten years, fair value		433,132
Due after ten years, fair value		233,827
Total		2,008,232
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		450,865
Due after one year through five years, amortized cost		399,330
Due after five years through ten years,amortized cost		55,808
Due after ten years, amortized cost		3,049
Total		909,052
Due in one year or less, fair value		451,370
Due after one year through five years, fair value		400,669
Due after five years through ten years, fair value		55,728
Due after ten years, fair value		3,019
Total		¥ 910,786
[1]	All Agency mortgage-backed securities presented in the above table are Ginnie Mae securities.

Investments - Additional Inform

Investments - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Gain (Loss) on Investments [Line Items]
Equity method Investments, carrying value	¥ 249,679	¥ 258,180
Held-to-maturity Securities
Gain (Loss) on Investments [Line Items]
Impairment loss on securities	¥ 0	0	¥ 0
Orient Corporation
Gain (Loss) on Investments [Line Items]
Percentage of proportionate share to the total outstanding common stock	49.00%
Equity securities (marketable)
Gain (Loss) on Investments [Line Items]
Equity method Investments, carrying value	¥ 132,817	124,830
Equity method Investments, aggregated market values	¥ 273,249	¥ 277,508

Investments (Other-Than-Tempora

Investments (Other-Than-Temporary Impairment Losses on Available-for-Sale Securities) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment on available-for-sale securities	¥ 12,167	¥ 38,061	¥ 1,068
Debt securities
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment on available-for-sale securities	138	4,020	450
Equity securities
Gain (Loss) on Investments [Line Items]
Other-than-temporary impairment on available-for-sale securities	¥ 12,029	¥ 34,041	¥ 618

Investments (Gross Unrealized L

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 Continuous Unrealized Loss Position (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		¥ 7,895,322	¥ 2,753,127
Less than 12 months Gross unrealized losses, available-for-sale securities		28,561	7,090
12 months or more Fair value, available-for-sale securities		433,597	237,627
12 months or more Gross unrealized losses, available-for-sale securities		4,697	3,225
Total Fair value, available-for-sale securities		8,328,919	2,990,754
Total Gross unrealized losses, available-for-sale securities		33,258	10,315
Less than 12 months, Fair value, held-to-maturity securities		460,882	394,673
Less than 12 months Gross unrealized losses, held-to-maturity securities		3,518	5,384
12 months or more Fair value, held-to-maturity securities		259,466	101,892
12 months or more Gross unrealized losses, held-to-maturity securities		4,413	882
Total Fair value, held-to-maturity securities		720,348	496,565
Total Gross unrealized losses, held-to-maturity securities		7,931	6,266
Debt securities | Agency mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities	[1]	195,887	15,965
Less than 12 months Gross unrealized losses, available-for-sale securities	[1]	3,705	86
12 months or more Fair value, available-for-sale securities	[1]	42,501	58,147
12 months or more Gross unrealized losses, available-for-sale securities	[1]	1,736	1,207
Total Fair value, available-for-sale securities	[1]	238,388	74,112
Total Gross unrealized losses, available-for-sale securities	[1],[2]	5,441	1,293
Less than 12 months, Fair value, held-to-maturity securities	[3]	460,882	394,673
Less than 12 months Gross unrealized losses, held-to-maturity securities	[3]	3,518	5,384
12 months or more Fair value, held-to-maturity securities	[3]	259,466	101,892
12 months or more Gross unrealized losses, held-to-maturity securities	[3]	4,413	882
Total Fair value, held-to-maturity securities	[3]	720,348	496,565
Total Gross unrealized losses, held-to-maturity securities	[3]	7,931	6,266
Debt securities | Japanese government bonds
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		5,574,649	1,531,400
Less than 12 months Gross unrealized losses, available-for-sale securities		15,796	692
12 months or more Fair value, available-for-sale securities		95,612	74,427
12 months or more Gross unrealized losses, available-for-sale securities		612	323
Total Fair value, available-for-sale securities		5,670,261	1,605,827
Total Gross unrealized losses, available-for-sale securities		16,408	1,015
Debt securities | Japanese local government bonds
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		58,700	3,434
Less than 12 months Gross unrealized losses, available-for-sale securities		233	3
Total Fair value, available-for-sale securities		58,700	3,434
Total Gross unrealized losses, available-for-sale securities		233	3
Debt securities | U.S. Treasury bonds and federal agency securities
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		1,013,962	315,425
Less than 12 months Gross unrealized losses, available-for-sale securities		4,578	32
Total Fair value, available-for-sale securities		1,013,962	315,425
Total Gross unrealized losses, available-for-sale securities		4,578	32
Debt securities | Other foreign government bonds
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		334,300	225,493
Less than 12 months Gross unrealized losses, available-for-sale securities		230	139
12 months or more Fair value, available-for-sale securities		8,327	225
12 months or more Gross unrealized losses, available-for-sale securities		6	14
Total Fair value, available-for-sale securities		342,627	225,718
Total Gross unrealized losses, available-for-sale securities		236	153
Debt securities | Residential mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		5,873	2,417
Less than 12 months Gross unrealized losses, available-for-sale securities		3	3
12 months or more Fair value, available-for-sale securities		28,994	39,984
12 months or more Gross unrealized losses, available-for-sale securities		555	875
Total Fair value, available-for-sale securities		34,867	42,401
Total Gross unrealized losses, available-for-sale securities		558	878
Debt securities | Commercial mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		8,314	40,471
Less than 12 months Gross unrealized losses, available-for-sale securities		218	300
12 months or more Fair value, available-for-sale securities		17,634	22,465
12 months or more Gross unrealized losses, available-for-sale securities		64	223
Total Fair value, available-for-sale securities		25,948	62,936
Total Gross unrealized losses, available-for-sale securities		282	523
Debt securities | Japanese corporate bonds and other debt securities
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		470,602	360,782
Less than 12 months Gross unrealized losses, available-for-sale securities		2,062	348
12 months or more Fair value, available-for-sale securities		158,713	20,109
12 months or more Gross unrealized losses, available-for-sale securities		224	72
Total Fair value, available-for-sale securities		629,315	380,891
Total Gross unrealized losses, available-for-sale securities	[4]	2,286	420
Debt securities | Foreign corporate bonds and other debt securities
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		202,347	186,478
Less than 12 months Gross unrealized losses, available-for-sale securities		1,353	972
12 months or more Fair value, available-for-sale securities		77,699	22,090
12 months or more Gross unrealized losses, available-for-sale securities		290	449
Total Fair value, available-for-sale securities		280,046	208,568
Total Gross unrealized losses, available-for-sale securities	[5]	1,643	1,421
Equity securities (marketable)
Gain (Loss) on Investments [Line Items]
Less than 12 months, Fair value, available-for-sale securities		30,688	71,262
Less than 12 months Gross unrealized losses, available-for-sale securities		383	4,515
12 months or more Fair value, available-for-sale securities		4,117	180
12 months or more Gross unrealized losses, available-for-sale securities		1,210	62
Total Fair value, available-for-sale securities		34,805	71,442
Total Gross unrealized losses, available-for-sale securities		¥ 1,593	¥ 4,577
[1]	Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥69,805 million and ¥4,307 million, respectively, at March 31, 2016, and ¥134,118 million and ¥104,270 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.
[2]	Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥168,604 million and ¥780,282 million, respectively, at March 31, 2016, and ¥134,240 million and ¥708,557 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Government National Mortgage Association ("Ginnie Mae") securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.
[3]	All Agency mortgage-backed securities presented in the above table are Ginnie Mae securities.
[4]	Other debt securities presented in the above table primarily consist of certificates of deposit ("CDs") and asset-backed securities ("ABS"), of which the total fair values were ¥158,446 million at March 31, 2016, and ¥155,138 million at March 31, 2017.
[5]	Other debt securities presented in the above table primarily consist of CDs, ABS, and collateralized loan obligations ("CLO"), of which the total fair values were ¥201,952 million at March 31, 2016, and ¥258,059 million at March 31, 2017.

Investments (Gross Unrealized85

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 Continuous Unrealized Loss Position (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Gain (Loss) on Investments [Line Items]
Fair value, available-for-sale securities		¥ 8,328,919	¥ 2,990,754
Agency mortgage-backed securities | Debt securities
Gain (Loss) on Investments [Line Items]
Fair value, available-for-sale securities	[1]	238,388	74,112
U.S. agency securities | Agency mortgage-backed securities | Debt securities
Gain (Loss) on Investments [Line Items]
Fair value, available-for-sale securities		134,118	69,805
Japanese agency securities | Agency mortgage-backed securities | Debt securities
Gain (Loss) on Investments [Line Items]
Fair value, available-for-sale securities		¥ 104,270	¥ 4,307
[1]	Agency mortgage-backed securities presented in the above table consist of U.S. agency securities and Japanese agency securities, of which the fair values were ¥69,805 million and ¥4,307 million, respectively, at March 31, 2016, and ¥134,118 million and ¥104,270 million, respectively, at March 31, 2017. U.S. agency securities primarily consist of Ginnie Mae securities, which are guaranteed by the United States government. All Japanese agency securities are mortgage-backed securities issued by Japan Housing Finance Agency, a Japanese government-sponsored enterprise.

Investments (Realized Gains (Lo

Investments (Realized Gains (Losses) on Sales of Available-for-Sale Securities) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains	¥ 353,036	¥ 297,344	¥ 220,250
Gross realized losses	(21,163)	(45,376)	(14,670)
Net realized gains (losses) on sales of available-for-sale securities	¥ 331,873	¥ 251,968	¥ 205,580

Investments (Composition of Oth

Investments (Composition of Other Investments) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Schedule of Cost-method Investments [Line Items]
Equity method investments	¥ 249,679	¥ 258,180
Investments held by consolidated investment companies	37,462	42,045
Other equity interests	307,928	313,221
Total	¥ 595,069	¥ 613,446

Loans (Loans Outstanding by Dom

Loans (Loans Outstanding by Domicile and Industry of Borrower) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[1]	¥ 82,439,581	¥ 77,722,525
Less: Unearned income and deferred loan fees-net		155,675	167,156
Loans outstanding		82,283,906	77,555,369
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		57,656,540	52,572,432
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		8,740,281	8,344,808
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		7,654,016	7,733,513
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,759,225	4,655,704
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,142,003	5,408,850
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,490,415	3,267,902
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,006,401	3,632,481
Domestic | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		8,532,246	3,395,784
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	4,427,349	4,619,336
Domestic | Mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,964,633	10,589,646
Domestic | Other individual loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		939,971	924,408
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		24,783,041	25,150,093
Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		6,759,921	6,382,449
Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		959,948	1,174,665
Foreign | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		16,872,448	17,319,284
Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	¥ 190,724	¥ 273,695
[1]	Amounts represent loan balances before deducting unearned income and deferred loan fees.
[2]	Other industries of Domestic and Other of Foreign include trade receivables and lease receivables of consolidated VIEs.

Loans - Additional Information

Loans - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net losses on sales of loans	¥ 919	¥ 1,752	¥ 33,291
Net losses on sales of loans, amount attributable to unrealized losses related to recording loans held for sale at the lower of cost or fair value	310	810	¥ 34,262
Impaired Financing Receivables with No Related Allowance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans partially charged off	¥ 26,513	¥ 31,933

Loans (Credit Quality Indicator

Loans (Credit Quality Indicators of Financing Receivables) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[1]	¥ 82,439,581	¥ 77,722,525
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		57,656,540	52,572,432
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		8,740,281	8,344,808
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		7,654,016	7,733,513
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,759,225	4,655,704
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,142,003	5,408,850
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,490,415	3,267,902
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,006,401	3,632,481
Domestic | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		8,532,246	3,395,784
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	4,427,349	4,619,336
Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		10,904,604	11,514,054
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		24,783,041	25,150,093
Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		6,759,921	6,382,449
Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		959,948	1,174,665
Foreign | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		16,872,448	17,319,284
Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	190,724	273,695
Financing Receivables Not Impaired | Normal obligors | A-B
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		41,703,710	39,473,402
Financing Receivables Not Impaired | Normal obligors | C-D
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		17,436,758	17,892,639
Financing Receivables Not Impaired | Normal obligors | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	11,445,049	12,115,160
Financing Receivables Not Impaired | Normal obligors | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	9,413,741	5,749,767
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		26,023,413	23,933,055
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,313,232	4,859,256
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,199,022	3,956,798
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,699,487	2,611,296
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,244,214	2,240,228
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,584,367	2,410,967
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		3,050,605	2,719,047
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,059,349	3,181,241
Financing Receivables Not Impaired | Normal obligors | Domestic | A-B | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	1,873,137	1,954,222
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		11,808,379	12,144,508
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,599,760	2,681,958
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,641,436	2,709,617
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		1,687,515	1,674,328
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		2,369,842	2,552,552
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		739,781	695,697
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		887,527	881,405
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		1,600	4,047
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	591,109	685,258
Financing Receivables Not Impaired | Normal obligors | Domestic | C-D | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		289,809	259,646
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	11,435,437	12,106,778
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	90,825	103,343
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	558,321	601,251
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	185,577	195,140
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	200,003	223,677
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	82,543	86,094
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	1,894	2,234
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[3]	3,535	3,501
Financing Receivables Not Impaired | Normal obligors | Domestic | Retail | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	10,312,739	10,891,538
Financing Receivables Not Impaired | Normal obligors | Domestic | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	6,604,632	2,616,911
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	67,734	148,102
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	15,585	157,057
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	910	2,380
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	22,785	57,865
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	1,092	380
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	37,907	3,788
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	4,471,297	210,496
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[4]	1,906,756	1,929,712
Financing Receivables Not Impaired | Normal obligors | Domestic | Other | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	80,566	107,131
Financing Receivables Not Impaired | Normal obligors | Foreign | A-B
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		15,680,297	15,540,347
Financing Receivables Not Impaired | Normal obligors | Foreign | A-B | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,628,387	5,129,904
Financing Receivables Not Impaired | Normal obligors | Foreign | A-B | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		741,478	942,366
Financing Receivables Not Impaired | Normal obligors | Foreign | A-B | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		9,310,432	9,468,077
Financing Receivables Not Impaired | Normal obligors | Foreign | C-D
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		5,628,379	5,748,131
Financing Receivables Not Impaired | Normal obligors | Foreign | C-D | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		592,380	550,380
Financing Receivables Not Impaired | Normal obligors | Foreign | C-D | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		214,558	224,514
Financing Receivables Not Impaired | Normal obligors | Foreign | C-D | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		4,814,906	4,966,929
Financing Receivables Not Impaired | Normal obligors | Foreign | C-D | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	6,535	6,308
Financing Receivables Not Impaired | Normal obligors | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	9,612	8,382
Financing Receivables Not Impaired | Normal obligors | Foreign | Retail | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3]	173	46
Financing Receivables Not Impaired | Normal obligors | Foreign | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[3]	9,439	8,336
Financing Receivables Not Impaired | Normal obligors | Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	2,809,109	3,132,856
Financing Receivables Not Impaired | Normal obligors | Foreign | Other | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	480,806	656,969
Financing Receivables Not Impaired | Normal obligors | Foreign | Other | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	1,082	2,940
Financing Receivables Not Impaired | Normal obligors | Foreign | Other | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4]	2,153,757	2,214,584
Financing Receivables Not Impaired | Normal obligors | Foreign | Other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[4]	173,464	258,363
Financing Receivables Not Impaired | Watch obligors | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	183,247	201,063
Financing Receivables Not Impaired | Watch obligors | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	136,424	121,340
Financing Receivables Not Impaired | Watch obligors | E1 to E2 Rating
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	1,139,768	1,179,451
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	183,239	201,053
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	11,589	12,473
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	16,023	16,408
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	23,189	24,846
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	32,911	39,486
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	9,698	10,518
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	353	264
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[3],[5]	410	329
Financing Receivables Not Impaired | Watch obligors | Domestic | Retail | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	89,066	96,729
Financing Receivables Not Impaired | Watch obligors | Domestic | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	44,949	40,733
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	1,314	2,958
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	317	255
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	204
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	501	546
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[4],[5]	41,179	35,315
Financing Receivables Not Impaired | Watch obligors | Domestic | Other | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	1,434	1,659
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	766,220	706,755
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	276,771	163,213
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	165,836	215,244
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	95,973	81,704
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	124,846	147,404
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	50,319	35,090
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	21,574	22,303
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[5]	4,613	7,053
Financing Receivables Not Impaired | Watch obligors | Domestic | E1 to E2 Rating | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	26,288	34,744
Financing Receivables Not Impaired | Watch obligors | Foreign | Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[3],[5]	8	10
Financing Receivables Not Impaired | Watch obligors | Foreign | Retail | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[3],[5]	8	10
Financing Receivables Not Impaired | Watch obligors | Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	91,475	80,607
Financing Receivables Not Impaired | Watch obligors | Foreign | Other | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[4],[5]	90,722	80,339
Financing Receivables Not Impaired | Watch obligors | Foreign | Other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[4],[5]	753	268
Financing Receivables Not Impaired | Watch obligors | Foreign | E1 to E2 Rating
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	373,548	472,696
Financing Receivables Not Impaired | Watch obligors | Foreign | E1 to E2 Rating | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	58,348	45,196
Financing Receivables Not Impaired | Watch obligors | Foreign | E1 to E2 Rating | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	2,801	4,801
Financing Receivables Not Impaired | Watch obligors | Foreign | E1 to E2 Rating | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[5]	312,275	422,567
Financing Receivables Not Impaired | Watch obligors | Foreign | E1 to E2 Rating | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2],[5]	124	132
Financing Receivables Impaired | Impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		980,884	989,703
Financing Receivables Impaired | Impaired loans | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		790,271	822,639
Financing Receivables Impaired | Impaired loans | Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		379,056	373,505
Financing Receivables Impaired | Impaired loans | Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		57,476	76,883
Financing Receivables Impaired | Impaired loans | Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		66,370	66,010
Financing Receivables Impaired | Impaired loans | Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		146,901	147,092
Financing Receivables Impaired | Impaired loans | Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		22,615	29,156
Financing Receivables Impaired | Impaired loans | Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		6,541	3,440
Financing Receivables Impaired | Impaired loans | Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	6,610	3,946
Financing Receivables Impaired | Impaired loans | Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		104,702	122,607
Financing Receivables Impaired | Impaired loans | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		190,613	167,064
Financing Receivables Impaired | Impaired loans | Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		29	44
Financing Receivables Impaired | Impaired loans | Foreign | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding		190,183	166,742
Financing Receivables Impaired | Impaired loans | Foreign | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding	[2]	¥ 401	¥ 278
[1]	Amounts represent loan balances before deducting unearned income and deferred loan fees.
[2]	Other industries of Domestic and Other of Foreign include trade receivables and lease receivables of consolidated VIEs.
[3]	Amounts represent small balance, homogeneous loans which are subject to pool allocations.
[4]	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.
[5]	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 (Impaired Loans) (Detail)

Loans (Impaired Loans) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	¥ 851,130	¥ 860,848
Recorded investment not requiring an allowance for loan losses	[1],[2]	129,754	128,855
Total	[1]	980,884	989,703
Unpaid principal balance		1,038,292	1,051,240
Related allowance	[3]	302,573	289,186
Average recorded investment		976,295	1,078,842
Interest income recognized	[4]	11,418	18,267
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	690,567	712,377
Recorded investment not requiring an allowance for loan losses	[1],[2]	99,704	110,262
Total	[1]	790,271	822,639
Unpaid principal balance		829,163	870,370
Related allowance	[3]	241,471	227,878
Average recorded investment		807,103	892,402
Interest income recognized	[4]	9,378	15,638
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	372,241	365,361
Recorded investment not requiring an allowance for loan losses	[1],[2]	6,815	8,144
Total	[1]	379,056	373,505
Unpaid principal balance		383,812	379,642
Related allowance	[3]	148,777	138,676
Average recorded investment		375,895	410,491
Interest income recognized	[4]	2,859	7,930
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	46,130	59,883
Recorded investment not requiring an allowance for loan losses	[1],[2]	11,346	17,000
Total	[1]	57,476	76,883
Unpaid principal balance		66,006	87,516
Related allowance	[3]	6,367	10,130
Average recorded investment		66,796	89,075
Interest income recognized	[4]	877	1,246
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	58,366	56,695
Recorded investment not requiring an allowance for loan losses	[1],[2]	8,004	9,315
Total	[1]	66,370	66,010
Unpaid principal balance		72,261	72,603
Related allowance	[3]	20,122	19,095
Average recorded investment		66,050	69,525
Interest income recognized	[4]	1,173	1,292
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	133,466	134,425
Recorded investment not requiring an allowance for loan losses	[1],[2]	13,435	12,667
Total	[1]	146,901	147,092
Unpaid principal balance		155,023	157,215
Related allowance	[3]	52,341	46,304
Average recorded investment		148,865	149,324
Interest income recognized	[4]	2,261	2,376
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	19,386	25,665
Recorded investment not requiring an allowance for loan losses	[1],[2]	3,229	3,491
Total	[1]	22,615	29,156
Unpaid principal balance		23,568	30,497
Related allowance	[3]	5,968	5,694
Average recorded investment		24,035	33,119
Interest income recognized	[4]	371	630
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	2,601	3,390
Recorded investment not requiring an allowance for loan losses	[1],[2]	3,940	50
Total	[1]	6,541	3,440
Unpaid principal balance		6,873	3,440
Related allowance	[3]	962	1,095
Average recorded investment		5,305	5,188
Interest income recognized	[4]	50	42
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	6,484	3,591
Recorded investment not requiring an allowance for loan losses	[1],[2]	126	355
Total	[1]	6,610	3,946
Unpaid principal balance		6,740	4,132
Related allowance	[3]	1,999	799
Average recorded investment		6,053	2,665
Interest income recognized	[4]	91	64
Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	51,893	63,367
Recorded investment not requiring an allowance for loan losses	[1],[2]	52,809	59,240
Total	[1]	104,702	122,607
Unpaid principal balance		114,880	135,325
Related allowance	[3]	4,935	6,085
Average recorded investment		114,104	133,015
Interest income recognized	[4]	1,696	2,058
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment requiring an allowance for loan losses	[1]	160,563	148,471
Recorded investment not requiring an allowance for loan losses	[1],[2]	30,050	18,593
Total	[1]	190,613	167,064
Unpaid principal balance		209,129	180,870
Related allowance	[3]	61,102	61,308
Average recorded investment		169,192	186,440
Interest income recognized	[4]	¥ 2,040	¥ 2,629
[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 small balance, homogeneous 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 small balance, homogeneous loans at March 31, 2016 and 2017 was ¥347,839 million and ¥302,251 million, respectively.
[4]	Amounts represent gross interest income on impaired loans which were included in Interest income on loans in the consolidated statements of income.

Loans (Impaired Loans) (Parenth

Loans (Impaired Loans) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment	[1]	¥ 980,884	¥ 989,703
Small balance homogeneous loans of which were collectively evaluated for impairment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment		¥ 302,251	¥ 347,839
[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.

Loans (Troubled Debt Restructur

Loans (Troubled Debt Restructuring) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]		¥ 67,107
Loan forgiveness or debt to equity swaps charge-off			34,360
Interest rate reduction and/or postponement of principal and/or interest		¥ 411,071	451,660
Domestic
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]		67,107
Loan forgiveness or debt to equity swaps charge-off			34,360
Interest rate reduction and/or postponement of principal and/or interest		375,386	406,912
Domestic | Manufacturing
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]		67,058
Loan forgiveness or debt to equity swaps charge-off			34,081
Interest rate reduction and/or postponement of principal and/or interest		106,697	108,395
Domestic | Construction and real estate
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		18,818	27,078
Domestic | Services
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		45,287	43,919
Domestic | Wholesale and retail
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		159,649	157,651
Domestic | Transportation and communications
Financing Receivable, Modifications [Line Items]
Loan forgiveness or debt to equity swaps Recorded investment	[1]		49
Loan forgiveness or debt to equity swaps charge-off			279
Interest rate reduction and/or postponement of principal and/or interest		17,417	28,244
Domestic | Banks and other financial institutions
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		7,933	6,342
Domestic | Other industries
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		2,518	7,120
Domestic | Individuals
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		17,067	28,163
Foreign
Financing Receivable, Modifications [Line Items]
Interest rate reduction and/or postponement of principal and/or interest		¥ 35,685	¥ 44,748
[1]	Amounts represent the book values of loans immediately after the restructurings.

Loans (Loans Modified as Troubl

Loans (Loans Modified as Troubled Debt Restructuring within Previous Twelve Months and for which There Was Payment Default During Current Fiscal Year) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Financing Receivable, Modifications [Line Items]
Recorded investment	¥ 28,948	¥ 55,281
Other industries
Financing Receivable, Modifications [Line Items]
Recorded investment	14
Domestic
Financing Receivable, Modifications [Line Items]
Recorded investment	25,735	44,435
Domestic | Manufacturing
Financing Receivable, Modifications [Line Items]
Recorded investment	5,164	10,669
Domestic | Construction and real estate
Financing Receivable, Modifications [Line Items]
Recorded investment	2,887	2,195
Domestic | Services
Financing Receivable, Modifications [Line Items]
Recorded investment	4,471	4,824
Domestic | Wholesale and retail
Financing Receivable, Modifications [Line Items]
Recorded investment	10,116	20,522
Domestic | Transportation and communications
Financing Receivable, Modifications [Line Items]
Recorded investment	795	2,361
Domestic | Individuals
Financing Receivable, Modifications [Line Items]
Recorded investment	2,288	3,864
Foreign
Financing Receivable, Modifications [Line Items]
Recorded investment	¥ 3,213	¥ 10,846

Loans (Age Analysis of Past Due

Loans (Age Analysis of Past Due Loans) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		¥ 242,397	¥ 200,117
Current		82,197,184	77,522,408
Total	[1]	82,439,581	77,722,525
Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		145,916	166,660
Current		57,510,624	52,405,772
Total		57,656,540	52,572,432
Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		10,065	11,172
Current		8,730,216	8,333,636
Total		8,740,281	8,344,808
Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		36,288	39,428
Current		7,617,728	7,694,085
Total		7,654,016	7,733,513
Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		7,048	9,718
Current		4,752,177	4,645,986
Total		4,759,225	4,655,704
Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		9,749	12,940
Current		5,132,254	5,395,910
Total		5,142,003	5,408,850
Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		2,565	2,708
Current		3,487,850	3,265,194
Total		3,490,415	3,267,902
Domestic | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current		4,006,401	3,632,481
Total		4,006,401	3,632,481
Domestic | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Current		8,532,246	3,395,784
Total		8,532,246	3,395,784
Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		69	29
Current		4,427,280	4,619,307
Total	[2]	4,427,349	4,619,336
Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		80,132	90,665
Current		10,824,472	11,423,389
Total		10,904,604	11,514,054
Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		96,481	33,457
Current		24,686,560	25,116,636
Total		24,783,041	25,150,093
Foreign | Banks and other financial institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total		6,759,921	6,382,449
Foreign | Government and public institutions
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total		959,948	1,174,665
30-59 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		40,928	50,075
30-59 Days Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		40,382	49,216
30-59 Days Past Due | Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,938	1,555
30-59 Days Past Due | Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		2,818	2,713
30-59 Days Past Due | Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		917	2,479
30-59 Days Past Due | Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,330	3,193
30-59 Days Past Due | Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		384	594
30-59 Days Past Due | Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		32,995	38,682
30-59 Days Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		546	859
60-89 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		17,187	18,545
60-89 Days Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		16,971	15,947
60-89 Days Past Due | Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		360	163
60-89 Days Past Due | Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		947	1,024
60-89 Days Past Due | Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		217	223
60-89 Days Past Due | Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		2,834	886
60-89 Days Past Due | Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		322	81
60-89 Days Past Due | Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		12,291	13,570
60-89 Days Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		216	2,598
90 Days or More Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		184,282	131,497
90 Days or More Past Due | Domestic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		88,563	101,497
90 Days or More Past Due | Domestic | Manufacturing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		7,767	9,454
90 Days or More Past Due | Domestic | Construction and real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		32,523	35,691
90 Days or More Past Due | Domestic | Services
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		5,914	7,016
90 Days or More Past Due | Domestic | Wholesale and retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		5,585	8,861
90 Days or More Past Due | Domestic | Transportation and communications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		1,859	2,033
90 Days or More Past Due | Domestic | Other industries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		69	29
90 Days or More Past Due | Domestic | Individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		34,846	38,413
90 Days or More Past Due | Foreign
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total past due		¥ 95,719	¥ 30,000
[1]	Amounts represent loan balances before deducting unearned income and deferred loan fees.
[2]	Other industries of Domestic and Other of Foreign include trade receivables and lease receivables of consolidated VIEs.

Allowance For Loan Losses (Chan

Allowance For Loan Losses (Changes in Allowance for Loan Losses) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		¥ 451,247	¥ 520,259	¥ 626,177
Provision (credit) for loan losses		37,668	34,560	(60,223)
Charge-offs		(31,252)	(112,319)	(79,222)
Recoveries		25,600	20,665	23,283
Net charge-offs		(5,652)	(91,654)	(55,939)
Others	[1]	(3,590)	(11,918)	10,244
Balance at end of fiscal year		479,673	451,247	520,259
Allowance for loan losses of which individually evaluated for impairment		288,942	238,941
Allowance for loan losses of which collectively evaluated for impairment		190,731	212,306
Loans	[2]	82,439,581	77,722,525
Loans of which individually evaluated for impairment	[2]	861,144	722,097
Loans of which collectively evaluated for impairment	[2]	81,578,437	77,000,428
Corporate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		367,739	423,177	501,349
Provision (credit) for loan losses		45,059	33,532	(40,167)
Charge-offs		(22,901)	(97,536)	(64,634)
Recoveries		18,320	17,232	19,086
Net charge-offs		(4,581)	(80,304)	(45,548)
Others	[1]	(890)	(8,666)	7,543
Balance at end of fiscal year		407,327	367,739	423,177
Allowance for loan losses of which individually evaluated for impairment		272,714	222,591
Allowance for loan losses of which collectively evaluated for impairment		134,613	145,148
Loans	[2]	61,120,654	59,385,962
Loans of which individually evaluated for impairment	[2]	772,647	634,049
Loans of which collectively evaluated for impairment	[2]	60,348,007	58,751,913
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		44,221	60,469	95,542
Provision (credit) for loan losses		(10,666)	(15,474)	(33,261)
Charge-offs		(1,754)	(2,173)	(3,266)
Recoveries		5,122	1,399	1,454
Net charge-offs		3,368	(774)	(1,812)
Balance at end of fiscal year		36,923	44,221	60,469
Allowance for loan losses of which individually evaluated for impairment		2,922	3,829
Allowance for loan losses of which collectively evaluated for impairment		34,001	40,392
Loans	[2]	11,722,726	12,414,453
Loans of which individually evaluated for impairment	[2]	23,422	24,768
Loans of which collectively evaluated for impairment	[2]	11,699,304	12,389,685
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of fiscal year		39,287	36,613	29,286
Provision (credit) for loan losses		3,275	16,502	13,205
Charge-offs		(6,597)	(12,610)	(11,322)
Recoveries		2,158	2,034	2,743
Net charge-offs		(4,439)	(10,576)	(8,579)
Others	[1]	(2,700)	(3,252)	2,701
Balance at end of fiscal year		35,423	39,287	¥ 36,613
Allowance for loan losses of which individually evaluated for impairment		13,306	12,521
Allowance for loan losses of which collectively evaluated for impairment		22,117	26,766
Loans	[2]	9,596,201	5,922,110
Loans of which individually evaluated for impairment	[2]	65,075	63,280
Loans of which collectively evaluated for impairment	[2]	¥ 9,531,126	¥ 5,858,830
[1]	Others includes primarily foreign exchange translation.
[2]	Amounts represent loan balances before deducting unearned income and deferred loan fees.

Allowance For Loan Losses - Add

Allowance For Loan Losses - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (Decrease) in provision for loan losses	¥ 3,108	¥ 94,783	¥ (66,007)

Premises and Equipment (Premise

Premises and Equipment (Premises and Equipment) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	¥ 3,293,125	¥ 3,037,843
Less: Accumulated depreciation and amortization	1,251,852	1,199,853
Premises and equipment-net	2,041,273	1,837,990
Land
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	575,054	552,205
Buildings
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	807,312	827,458
Equipment and furniture
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	485,407	463,205
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	93,967	88,195
Construction in Progress
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	23,093	20,656
Software and Software Development Costs
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	¥ 1,308,292	¥ 1,086,124

Premises and Equipment - Additi

Premises and Equipment - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation and amortization	¥ 163,769	¥ 162,676	¥ 161,152
Premises and equipment under capital leases
Property, Plant and Equipment [Line Items]
Premises and equipment under capital leases	80,430	69,077
Premises and equipment under capital leases, accumulated depreciation and amortization	¥ 40,155	¥ 34,733

Goodwill and Intangible Asse100

Goodwill and Intangible Assets (Changes in Goodwill) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017		Mar. 31, 2016		Mar. 31, 2015
Goodwill [Line Items]
Balance at beginning of fiscal year		¥ 19,097		¥ 11,703		¥ 11,549
Goodwill acquired		76,225	[1]	16,470	[2]
Impairment losses recognized				(6,222)
Foreign exchange translation		(146)		(2,854)		154
Balance at end of fiscal year		95,176		19,097		11,703
Gross amount of goodwill	[3]	171,432		94,473		81,254
Accumulated impairment losses		¥ 76,256		¥ 75,376		¥ 69,551
[1]	Goodwill acquired is entirely related to the acquisition of Asset Management One (see Note 3 "Business combination").
[2]	Goodwill acquired is entirely related to the acquisition of Simplex Real Estate Management Inc. and Simplex REIT Partners Inc.
[3]	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 32 "Business segment information".

Goodwill and Intangible Asse101

Goodwill and Intangible Assets - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill impairment loss recognized		¥ 6,222
Intangible assets amortization expense recognized	¥ 7,433	¥ 5,254	¥ 5,376

Goodwill and Intangible Asse102

Goodwill and Intangible Assets (Gross Carrying Amount Accumulated Amortization and Net Carrying Amount of Intangible Assets) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Intangible Assets by Major Class [Line Items]
Gross carrying amount		¥ 129,793	¥ 76,813
Gross carrying amount		9,061	9,224
Net carrying amount		9,061	9,224
Gross carrying amount		138,854	86,037
Accumulated amortization		44,707	37,386
Net carrying amount		85,086	39,427
Net carrying amount		94,147	48,651
Customer relationships
Intangible Assets by Major Class [Line Items]
Gross carrying amount	[1]	126,979	73,949
Accumulated amortization	[1]	42,517	35,178
Net carrying amount	[1]	84,462	38,771
Other
Intangible Assets by Major Class [Line Items]
Gross carrying amount		2,814	2,864
Accumulated amortization		2,190	2,208
Net carrying amount		¥ 624	¥ 656
[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 3 "Business combination" for further details of the integration among asset management companies. See Note 1 "Basis of presentation and summary of significant accounting policies" for further information.

Goodwill and Intangible Asse103

Goodwill and Intangible Assets (Estimated Aggregate Amortization Expense in Respect of Intangible Assets) (Detail) ¥ in Millions	Mar. 31, 2017JPY (¥)
Finite-Lived Intangible Assets [Line Items]
2,018	¥ 9,465
2,019	9,243
2,020	8,940
2,021	8,232
2,022	¥ 7,699

Pledged Assets and Collatera104

Pledged Assets and Collateral (Amounts Pledged as Collateral for Borrowings and for Other Purpose) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Financial Instruments Owned and Pledged as Collateral [Line Items]
Interest-bearing deposits in other banks	¥ 51	¥ 69
Trading account assets	6,577	7,939
Investments	8,213	10,254
Loans	7,468	5,871
Other assets	1,588	1,322
Total	¥ 23,897	¥ 25,455

Pledged Assets and Collatera105

Pledged Assets and Collateral (Association Liabilities Collateralized by Pledged Assets) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Deposits	¥ 919	¥ 813
Payables under repurchase agreements	6,109	6,182
Payables under securities lending transactions	1,460	2,790
Other short-term borrowings	686	657
Long-term debt	4,220	5,545
Total	¥ 13,394	¥ 15,987

Pledged Assets and Collateral -

Pledged Assets and Collateral - Additional Information (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
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	¥ 44,741	¥ 34,377
Reserve funds requires to be maintained by MHFG Group	1,462	1,322
Fair value collateral received that can be sold or repledged	13,395	12,116
Fair value collateral received that can be sold or repledged, value of collateral sold or repledged	¥ 12,988	¥ 11,616

Deposits (Balances of Time Depo

Deposits (Balances of Time Deposits and Certificates of Deposit Issued by Domestic Offices in Amounts of Yen Ten Million or more and Balances of those Deposits Issued by Foreign Offices in Amounts of United States One Hundred Thousand Dollars or more) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	¥ 23,640,152	¥ 25,642,380
Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	19,616,400	18,102,837
Time deposits | Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	17,763,052	19,209,570
Time deposits | Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	14,862,230	12,708,142
Certificates of deposit | Domestic
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	5,877,100	6,432,810
Certificates of deposit | Foreign
Deposits From Banking Clients [Line Items]
Domestic deposit in amounts of YEN 10 million or more	¥ 4,754,170	¥ 5,394,695

Deposits - Additional Informati

Deposits - Additional Information (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Deposits From Banking Clients [Line Items]
Aggregate amount of demand deposits in overdraft status that have been reclassified as loan balances	¥ 718	¥ 890

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, 2017JPY (¥)
Deposits From Banking Clients [Line Items]
Total	¥ 52,361,217
Bank Time Deposits Liabilities Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	22,800,247
Due after one year through two years	2,024,310
Due after two years through three years	1,206,888
Due after three years through four years	349,896
Due after four years through five years	346,569
Due after five years	133,581
Total	26,861,491
Certificates Of Deposit Liabilities Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	5,821,000
Due after one year through two years	56,100
Total	5,877,100
Time deposits
Deposits From Banking Clients [Line Items]
Total	41,729,940
Certificates of deposit
Deposits From Banking Clients [Line Items]
Total	10,631,277
Bank Time Deposits Liabilities Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	14,765,251
Due after one year through two years	88,304
Due after two years through three years	5,740
Due after four years through five years	198
Due after five years	8,956
Total	14,868,449
Certificates Of Deposit Liabilities Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	4,599,583
Due after one year through two years	38,709
Due after two years through three years	55,818
Due after three years through four years	60,067
Total	4,754,177
Domestic
Deposits From Banking Clients [Line Items]
Due in one year or less	28,621,247
Due after one year through two years	2,080,410
Due after two years through three years	1,206,888
Due after three years through four years	349,896
Due after four years through five years	346,569
Due after five years	133,581
Total	32,738,591
Foreign
Deposits From Banking Clients [Line Items]
Due in one year or less	19,364,834
Due after one year through two years	127,013
Due after two years through three years	61,558
Due after three years through four years	60,067
Due after four years through five years	198
Due after five years	8,956
Total	¥ 19,622,626

Short-Term Borrowings and Lo110

Short-Term Borrowings and Long-Term Debt (Details of Other Short-Term Borrowings) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Short-term Debt [Line Items]
Borrowings from the Bank of Japan		¥ 355,255	¥ 324,146
Other		105,303	97,372
Total		1,476,612	2,080,039
Mizuho Financial Group Inc
Short-term Debt [Line Items]
Commercial paper and short-term notes issued	[1],[2]	956,447	1,369,302
Consolidated VIEs
Short-term Debt [Line Items]
Commercial paper and short-term notes issued	[2],[3]	59,607	289,219
Total		¥ 60,575	¥ 292,614
[1]	Commercial paper and short-term notes issued by MHFG and its subsidiaries in the above table consist of commercial paper and short-term notes, of which the amounts were ¥777,602 million and ¥591,700 million, respectively, at March 31, 2016, and ¥765,147 million and ¥191,300 million, respectively, at March 31, 2017.
[2]	Short-term notes are issued under the laws of Japan in the form of dematerialized commercial paper, whose characteristics are economically the same as commercial paper.
[3]	Commercial paper and short-term notes issued by consolidated VIEs of asset-backed commercial paper programs in the above table consist of commercial paper and short-term notes, of which the amounts were ¥232,538 million and ¥56,681 million, respectively, at March 31, 2016, and ¥24,559 million and ¥35,048 million, respectively, at March 31, 2017.

Short-Term Borrowings and Lo111

Short-Term Borrowings and Long-Term Debt (Details of Other Short-Term Borrowings) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Consolidated VIEs
Short-term Debt [Line Items]
Commercial paper	¥ 24,559	¥ 232,538
Short-term notes	35,048	56,681
Mizuho Financial Group Inc
Short-term Debt [Line Items]
Commercial paper	765,147	777,602
Short-term notes	¥ 191,300	¥ 591,700

Short-Term Borrowings and Lo112

Short-Term Borrowings and Long-Term Debt (Long-Term Debt with Original Maturities of More than One Year) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Debt Instrument [Line Items]
Obligations under capital leases	¥ 40,947	¥ 37,811
Loan participation borrowings	90,639	64,524
Senior borrowings and bonds	11,119,136	11,576,384
Subordinated borrowings and bonds	3,278,692	3,086,808
Total	¥ 14,529,414	¥ 14,765,527

Short-Term Borrowings and Lo113

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, 2017	Mar. 31, 2016
Debt Instrument [Line Items]
Borrowings and bonds		¥ 14,397,828	¥ 14,663,192
Senior borrowings and bonds
Debt Instrument [Line Items]
Borrowings and bonds		11,119,136	11,576,384
Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		6,011,939	7,863,984
Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		2,533,715	1,778,892
Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Borrowings and bonds		172,370	135,515
Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		717,056	852,425
Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		1,557,288	898,840
Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Borrowings and bonds		126,768	46,728
Subordinated borrowings and bonds
Debt Instrument [Line Items]
Borrowings and bonds		3,278,692	3,086,808
Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Borrowings and bonds		2,858,445	2,596,460
Subordinated borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Borrowings and bonds		¥ 420,247	¥ 490,348
Minimum | Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2017-04
Minimum | Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2017-04
Minimum | Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	0.01%
Maturities, Start	[2]	2017-04
Minimum | Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2017-04
Minimum | Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2017-04
Minimum | Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	0.00%
Maturities, Start	[2]	2017-08
Minimum | Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	0.50%
Maturities, Start	[2]	2017-04
Minimum | 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
Maximum | Senior borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	10.00%
Maturities, End	[2]	2046-12
Maximum | Senior borrowings and bonds | Fixed Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	7.49%
Maturities, End	[2]	2046-08
Maximum | Senior borrowings and bonds | Fixed Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	10.00%
Maturities, End	[2]	2037-05
Maximum | Senior borrowings and bonds | Floating Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	23.80%
Maturities, End	[2]	2047-03
Maximum | Senior borrowings and bonds | Floating Rate | Denominated in U.S. dollars
Debt Instrument [Line Items]
Interest rates	[1]	10.00%
Maturities, End	[2]	2033-07
Maximum | Senior borrowings and bonds | Floating Rate | Denominated in other currencies
Debt Instrument [Line Items]
Interest rates	[1]	9.40%
Maturities, End	[2]	2035-09
Maximum | Subordinated borrowings and bonds | Fixed Rate | Denominated in Japanese yen
Debt Instrument [Line Items]
Interest rates	[1]	4.26%
Maximum | 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
[1]	The interest rates disclosed reflect the range of contractual rates in effect at March 31, 2017.
[2]	Maturity information disclosed is the range of maturities at March 31, 2017.

Short-Term Borrowings and Lo114

Short-Term Borrowings and Long-Term Debt (Contractual Maturities of Long-Term Debt) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Debt Instrument [Line Items]
2,018	¥ 1,614,386
2,019	3,127,227
2,020	1,733,501
2,021	1,841,416
2,022	1,194,536
2023 and thereafter	5,018,348
Total	¥ 14,529,414	¥ 14,765,527

Other Assets and Liabilities (S

Other Assets and Liabilities (Schedule of Other Assets and Other Liabilities) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Other assets:
Accounts receivable from brokers, dealers and customers for securities transactions	¥ 1,564,295	¥ 1,718,769
Collateral provided for derivative transactions	973,404	884,651
Prepaid pension cost	682,592	612,102
Miscellaneous receivables	324,135	286,896
Margins provided for futures contracts	276,398	225,240
Security deposits	122,858	113,066
Loans held for sale	26,689	33,133
Other	1,021,958	823,033
Total	4,992,329	4,696,890
Other liabilities:
Accounts payable to brokers, dealers and customers for securities transactions	1,400,141	2,882,824
Guaranteed trust principal	683,324	623,904
Collateral accepted for derivative transactions	671,691	715,894
Miscellaneous payables	481,809	442,352
Margins accepted for futures contracts	307,066	334,925
Unearned income	134,666	144,903
Factoring amounts owed to customers	53,488	242,392
Other	1,294,340	1,089,529
Total	¥ 5,026,525	¥ 6,476,723

Preferred Stock (Composition of

Preferred Stock (Composition of Preferred Stock) (Detail) - JPY (¥) ¥ / shares in Units, ¥ in Millions		12 Months Ended
		Mar. 31, 2016		Mar. 31, 2015		Mar. 31, 2017
Class of Stock [Line Items]
Aggregate amount		¥ 914,752		¥ 914,752
Number of shares Authorized		4,214,752,000		4,214,752,000		4,214,752,000
Number of shares Issued		914,752,000		914,752,000
Number of shares In treasury		10,929,211				19,992,754
Preferred stock
Class of Stock [Line Items]
Number of shares In treasury		815,828,400		701,631,100
Eleventh series class XI preferred stock
Class of Stock [Line Items]
Aggregate amount	[1]	¥ 914,752		¥ 914,752
Number of shares Authorized		914,752,000	[1]	914,752,000	[1]	914,752,000
Number of shares Issued	[1]	914,752,000		914,752,000
Liquidation value per share	[1]	¥ 1,000		¥ 1,000
Convertible or not	[1]	Yes		Yes
Eleventh series class XI preferred stock | Preferred stock
Class of Stock [Line Items]
Number of shares In treasury	[1]	815,828,400		701,631,100
First series class XIV preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[2]	900,000,000		900,000,000		900,000,000
Second series class XIV preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[2]	900,000,000		900,000,000		900,000,000
Third series class XIV preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[2]	900,000,000		900,000,000		900,000,000
Fourth series class XIV preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[2]	900,000,000		900,000,000		900,000,000
First series class XV preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[3]	900,000,000		900,000,000		900,000,000
Second series class XV preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[3]	900,000,000		900,000,000		900,000,000
Third series class XV preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[3]	900,000,000		900,000,000		900,000,000
Fourth series class XV preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[3]	900,000,000		900,000,000		900,000,000
First series class XVI preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[4]	1,500,000,000		1,500,000,000		1,500,000,000
Second series class XVI preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[4]	1,500,000,000		1,500,000,000		1,500,000,000
Third series class XVI preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[4]	1,500,000,000		1,500,000,000		1,500,000,000
Fourth series class XVI preferred stock
Class of Stock [Line Items]
Number of shares Authorized	[4]	1,500,000,000		1,500,000,000		1,500,000,000
[1]	The aggregate amount and number of issued shares include the preferred stock in treasury which has been converted into common stock but not yet cancelled.
[2]	The total number of authorized shares from first to fourth series class XIV preferred stock shall not exceed 900,000,000.
[3]	The total number of authorized shares from first to fourth series class XV preferred stock shall not exceed 900,000,000.
[4]	The total number of authorized shares from first to fourth series class XVI preferred stock shall not exceed 1,500,000,000.

Preferred Stock (Composition117

Preferred Stock (Composition of Preferred Stock) (Parenthetical) (Detail) - shares	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Class of Stock [Line Items]
Number of shares Authorized	4,214,752,000	4,214,752,000	4,214,752,000
First to fourth series class XIV Preferred Stock | Maximum
Class of Stock [Line Items]
Number of shares Authorized	900,000,000
First to fourth series class XV Preferred Stock | Maximum
Class of Stock [Line Items]
Number of shares Authorized	900,000,000
First to fourth series class XVI Preferred Stock | Maximum
Class of Stock [Line Items]
Number of shares Authorized	1,500,000,000

Preferred Stock (Changes in Num

Preferred Stock (Changes in Number of Shares and Aggregate Amount of Preferred Stock) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Class of Stock [Line Items]
Balance at beginning of fiscal year		¥ 8,183,191	¥ 8,189,844
Balance at end of fiscal year		¥ 8,772,057	¥ 8,183,191	¥ 8,189,844
Preferred stock
Class of Stock [Line Items]
Issued at beginning of year		914,752,000	914,752,000	914,752,000
Net change		(914,752,000)
Issued at end of year			914,752,000	914,752,000
Balance at beginning of fiscal year		¥ 98,924	¥ 213,121	¥ 312,651
Balance at end of fiscal year			¥ 98,924	¥ 213,121
Preferred stock | Eleventh series class XI preferred stock
Class of Stock [Line Items]
Issued at beginning of year	[1]	914,752,000	914,752,000	914,752,000
Net change	[1]	(914,752,000)
Issued at end of year	[1]		914,752,000	914,752,000
Preferred stock | Stock Issued
Class of Stock [Line Items]
Balance at beginning of fiscal year		¥ 914,752	¥ 914,752	¥ 914,752
Net change		(914,752)
Balance at end of fiscal year			914,752	914,752
Preferred stock | Stock Issued | Eleventh series class XI preferred stock
Class of Stock [Line Items]
Balance at beginning of fiscal year	[1]	914,752	914,752	914,752
Net change	[1]	(914,752)
Balance at end of fiscal year	[1]		¥ 914,752	¥ 914,752
[1]	In July 2016, all shares of the eleventh series class XI preferred stock were converted into common stock and cancelled.

Common Stock (Changes in Number

Common Stock (Changes in Number of Issued Shares of Common Stock) (Detail) - shares	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Class of Stock [Line Items]
Balance at beginning of fiscal year	25,030,525,657	24,621,897,967	24,263,885,187
Issuance of new shares of common stock due to conversion of Eleventh series class XI preferred stock	349,677,288	403,667,690	351,822,780
Issuance of new shares of common stock due to exercise of stock acquisition rights	6,105,000	4,960,000	6,190,000
Balance at end of fiscal year	25,386,307,945	25,030,525,657	24,621,897,967

Dividends - Additional Informat

Dividends - Additional Information (Detail) ¥ in Millions	12 Months Ended
	Mar. 31, 2017JPY (¥)
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital stock	¥ 2,256,275
Capital surplus	1,196,259
Retained earnings	¥ 1,839,725
Description of dividend payment restrictions	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	10.00%
Legal reserve	¥ 1,200,517
Maximum amount available for dividends under Company Law and the Banking Law	¥ 1,831,321
Minimum Common Equity Tier 1 ratio required for capital adequacy purposes	4.50%
Japan Gaap Additional Paid-in Capital
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Legal reserve	¥ 1,196,167
Japan Gaap Retained Earnings
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Legal reserve	¥ 4,350

Dividends (Dividends on Preferr

Dividends (Dividends on Preferred Stock and Common Stock) (Detail) - JPY (¥) ¥ / shares in Units, ¥ in Millions	12 Months Ended
	Mar. 31, 2017		Mar. 31, 2016	Mar. 31, 2015
Japan Gaap Dividends Payable [Line Items]
Cash dividends In aggregate	¥ 190,002		¥ 195,265	¥ 176,137
Eleventh series class XI preferred stock
Japan Gaap Dividends Payable [Line Items]
Cash dividends Per share	¥ 10	[1]	¥ 20	¥ 20
Cash dividends In aggregate	¥ 989	[1]	¥ 3,572	¥ 5,906
Common stock
Japan Gaap Dividends Payable [Line Items]
Cash dividends Per share	¥ 7.50		¥ 7.75	¥ 7
Cash dividends In aggregate	¥ 189,013		¥ 191,693	¥ 170,231
[1]	In July 2016, all shares of the eleventh series class XI preferred stock were converted into common stock and cancelled. Consequently, the amount for the fiscal year does not include interim dividends.

Accumulated Other Comprehens122

Accumulated Other Comprehensive Income (Changes in Each Component of Accumulated Other Comprehensive Income (Loss), Net of Tax) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	¥ 8,183,191	¥ 8,189,844
Less: reclassification adjustments for losses (gains) included in net income	(222,020)
Change during year	51,557	(573,642)	¥ 922,612
Balance at end of fiscal year	8,772,057	8,183,191	8,189,844
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	1,469,638	2,041,005	1,117,877
Change during year	51,525	(571,697)	923,128
Balance at end of fiscal year	1,521,163	1,469,638	2,041,005
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	1,409,374	1,747,607	1,123,272
Foreign currency translation adjustments during year	273,844	(189,479)	763,115
Less: reclassification adjustments for losses (gains) included in net income	(221,916)	(148,669)	(138,780)
Change during year	51,928	(338,148)	624,335
Balance at end of fiscal year	1,461,302	1,409,374	1,747,607
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	6,725	129,179	(6,434)
Foreign currency translation adjustments during year	(11,920)	(122,081)	134,104
Less: reclassification adjustments for losses (gains) included in net income	(340)	(788)	1,509
Change during year	(12,260)	(122,869)	135,613
Balance at end of fiscal year	(5,535)	6,725	129,179
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	53,539	164,219	1,039
Foreign currency translation adjustments during year	11,561	(107,497)	163,191
Less: reclassification adjustments for losses (gains) included in net income	296	(3,183)	(11)
Change during year	11,857	(110,680)	163,180
Balance at end of fiscal year	65,396	53,539	¥ 164,219
Previously Reported | Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	1,469,308
Balance at end of fiscal year		1,469,308
Previously Reported | Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	1,409,459
Balance at end of fiscal year		1,409,459
Previously Reported | Accumulated Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	6,310
Balance at end of fiscal year		6,310
Restatement Adjustment | Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	330
Balance at end of fiscal year		330
Restatement Adjustment | Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	(85)
Balance at end of fiscal year		(85)
Restatement Adjustment | Accumulated Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of fiscal year	¥ 415
Balance at end of fiscal year		¥ 415

Accumulated Other Comprehens123

Accumulated Other Comprehensive Income (Amounts Reclassified Out of Accumulated Other Comprehensive Income into Net Income) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	[1]	¥ 319,571
Tax effect	[2]	(97,551)
Net of tax before allocation to noncontrolling interests		222,020
Net of tax attributable to noncontrolling interests	[2]	(60)
Net of tax attributable to MHFG shareholders		221,960
Accumulated Net Unrealized Investment Gain (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax before allocation to noncontrolling interests		221,916	¥ 148,669	¥ 138,780
Accumulated Net Unrealized Investment Gain (Loss) | Investment gains (losses)-net
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	[1]	319,707
Tax effect	[2]	(97,729)
Net of tax before allocation to noncontrolling interests		221,978
Net of tax attributable to noncontrolling interests	[2]	(62)
Net of tax attributable to MHFG shareholders		221,916
Accumulated Net Unrealized Investment Gain (Loss) | Foreign exchange adjustments gains (losses)-net
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	[1]	340
Net of tax before allocation to noncontrolling interests		340
Net of tax attributable to MHFG shareholders		340
Accumulated Defined Benefit Plans Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax before allocation to noncontrolling interests		(296)	¥ 3,183	¥ 11
Accumulated Defined Benefit Plans Adjustment | Salaries and employee benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Before tax	[1]	(476)
Tax effect	[2]	178
Net of tax before allocation to noncontrolling interests		(298)
Net of tax attributable to noncontrolling interests	[2]	2
Net of tax attributable to MHFG shareholders		¥ (296)
[1]	The amounts in the Before tax column are recorded in each account presented under the heading "Affected line items in the consolidated statements of income".
[2]	The amounts in the Tax effect column and Net of tax attributable to noncontrolling interests column are recorded in Income tax expense and Net income (loss) attributable to noncontrolling interests in the consolidated statements of income, respectively.

Regulatory Matters - Additional

Regulatory Matters - Additional Information (Detail) ¥ in Billions	12 Months Ended
	Mar. 31, 2017JPY (¥)
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	120.00%
Increments of capital investment	10.00%
Additional Tier 1 capital	¥ 577.5
Tier 2 capital	¥ 842.1
Common Equity Tier 1 capital requirement, including capital conservation buffer	7.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%
Adjustment in the calculation of Common Equity	20.00%
Increased in Common Equity	20.00%
Date at which regulatory adjustments reach 100%	2018-03
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.
Minimum
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Buffer ranging percentage	0.00%
Minimum | G-SIB
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	1.00%
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%
Maximum
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Buffer ranging percentage	2.50%
Maximum | G-SIB
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital adequacy ratio	2.50%
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 2,016
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital conservation buffer	0.625%
Additional loss absorbency requirements for G-SIBs and D-SIBs	0.25%	[1]
March 2,019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements [Line Items]
Capital conservation buffer	2.50%
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[1]
[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.

Regulatory Matters (Capital Req

Regulatory Matters (Capital Requirements and Regulatory Adjustments Over Transitional Period) (Detail)	12 Months Ended
	Mar. 31, 2017
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 2,016
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Capital conservation buffer	0.625%
Phase out of recognition of capital instruments that no longer qualify as capital	60.00%
Phase-in of deductions from capital	60.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	0.25%	[1]
March 2016 | 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 2016 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	6.00%
March 2,017
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Capital conservation buffer	1.25%
Phase out of recognition of capital instruments that no longer qualify as capital	50.00%
Phase-in of deductions from capital	80.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	0.50%	[1]
March 2017 | 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 2017 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	6.00%
March 2,018
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Capital conservation buffer	1.875%
Phase out of recognition of capital instruments that no longer qualify as capital	40.00%
Phase-in of deductions from capital	100.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	0.75%	[1]
March 2018 | 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 2018 | Tier I
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	6.00%
March 2,019
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Capital conservation buffer	2.50%
Phase out of recognition of capital instruments that no longer qualify as capital	30.00%
Phase-in of deductions from capital	100.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[1]
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 2,020
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Capital conservation buffer	2.50%
Phase out of recognition of capital instruments that no longer qualify as capital	20.00%
Phase-in of deductions from capital	100.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[1]
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 2,021
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Capital conservation buffer	2.50%
Phase out of recognition of capital instruments that no longer qualify as capital	10.00%
Phase-in of deductions from capital	100.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[1]
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 2,022
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Minimum total capital	8.00%
Capital conservation buffer	2.50%
Phase out of recognition of capital instruments that no longer qualify as capital	0.00%
Phase-in of deductions from capital	100.00%
Additional loss absorbency requirements for G-SIBs and D-SIBs	1.00%	[1]
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%
[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.

Regulatory Matters (Capital 126

Regulatory Matters (Capital Requirements and Regulatory Adjustments Over Transitional Period) (Parenthetical) (Detail)	12 Months Ended
	Mar. 31, 2017
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%

Regulatory Matters (Capital Ade

Regulatory Matters (Capital Adequacy Ratios of MHFG MHBK and MHTB) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Total risk-based capital:
Actual		¥ 2,256,275
Common Equity Tier 1 capital:
Required		4.50%
Total risk-based capital:
Required		120.00%
Mizuho Financial Group Inc | Consolidated
Common Equity Tier 1 capital:
Required	[1]	¥ 3,857,000	¥ 3,361,000
Actual		7,002,000	6,566,000
Tier 1 capital:
Required	[1]	4,783,000	4,299,000
Actual		8,212,000	7,905,000
Total risk-based capital:
Required	[1]	6,017,000	5,550,000
Actual		¥ 10,051,000	¥ 9,639,000
Common Equity Tier 1 capital:
Required	[1]	6.25%	5.375%
Actual		11.34%	10.50%
Tier 1 capital:
Required	[1]	7.75%	6.875%
Actual		13.30%	12.64%
Total risk-based capital:
Required	[1]	9.75%	8.875%
Actual		16.28%	15.41%
Mizuho Bank Limited | Consolidated
Common Equity Tier 1 capital:
Required		¥ 2,541,000	¥ 2,555,000
Actual		6,304,000	6,142,000
Tier 1 capital:
Required		3,388,000	3,406,000
Actual		7,536,000	7,244,000
Total risk-based capital:
Required		4,517,000	4,542,000
Actual		¥ 9,149,000	¥ 8,780,000
Common Equity Tier 1 capital:
Required		4.50%	4.50%
Actual		11.16%	10.81%
Tier 1 capital:
Required		6.00%	6.00%
Actual		13.34%	12.75%
Total risk-based capital:
Required		8.00%	8.00%
Actual		16.20%	15.46%
Mizuho Bank Limited | Non-consolidated
Common Equity Tier 1 capital:
Required		¥ 2,432,000	¥ 2,489,000
Actual		6,057,000	5,892,000
Tier 1 capital:
Required		3,243,000	3,318,000
Actual		7,316,000	7,004,000
Total risk-based capital:
Required		4,324,000	4,424,000
Actual		¥ 8,938,000	¥ 8,576,000
Common Equity Tier 1 capital:
Required		4.50%	4.50%
Actual		11.20%	10.65%
Tier 1 capital:
Required		6.00%	6.00%
Actual		13.53%	12.66%
Total risk-based capital:
Required		8.00%	8.00%
Actual		16.53%	15.50%
Mizuho Trust & Banking Company Limited | Consolidated
Common Equity Tier 1 capital:
Required		¥ 112,000	¥ 109,000
Actual		466,000	440,000
Tier 1 capital:
Required		149,000	145,000
Actual		466,000	440,000
Total risk-based capital:
Required		199,000	193,000
Actual		¥ 485,000	¥ 472,000
Common Equity Tier 1 capital:
Required		4.50%	4.50%
Actual		18.73%	18.21%
Tier 1 capital:
Required		6.00%	6.00%
Actual		18.73%	18.21%
Total risk-based capital:
Required		8.00%	8.00%
Actual		19.47%	19.52%
Mizuho Trust & Banking Company Limited | Non-consolidated
Common Equity Tier 1 capital:
Required		¥ 113,000	¥ 109,000
Actual		475,000	448,000
Tier 1 capital:
Required		150,000	145,000
Actual		475,000	448,000
Total risk-based capital:
Required		200,000	194,000
Actual		¥ 493,000	¥ 480,000
Common Equity Tier 1 capital:
Required		4.50%	4.50%
Actual		18.98%	18.52%
Tier 1 capital:
Required		6.00%	6.00%
Actual		18.98%	18.52%
Total risk-based capital:
Required		8.00%	8.00%
Actual		19.70%	19.80%
[1]	The required ratios disclosed above, at March 31, 2016 and 2017, include the transitional capital conservation buffer of 0.625% and 1.25%, respectively, and the transitional additional loss absorbency requirements for G-SIBs and D-SIBs of 0.25% and 0.5%, respectively, which are both in addition to the regulatory minima. The respective required amounts are determined by applying the ratios to the sum of the risk weighted assets and certain other risk amounts.

Regulatory Matters (Capital 128

Regulatory Matters (Capital Adequacy Ratios of MHFG MHBK and MHTB) (Parenthetical) (Detail)		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Japan Gaap Schedule Of Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer		1.25%	0.625%
Additional loss absorbency requirements for G-SIBs and D-SIBs		1.00%
March 2,016
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]	0.25%
March 2,017
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]	0.50%
[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.

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, 2017	Mar. 31, 2016	Mar. 31, 2015
Net income:
Net income attributable to MHFG shareholders		¥ 362,440	¥ 850,492	¥ 803,048
Less: Net income attributable to preferred shareholders			2,430	4,910
Net income attributable to common shareholders		362,440	848,062	798,138
Effect of dilutive securities:
Convertible preferred stock			2,430	4,910
Net income attributable to common shareholders after assumed conversions		¥ 362,440	¥ 850,492	¥ 803,048
Shares:
Weighted average common shares outstanding		25,285,899	24,806,161	24,368,116
Effect of dilutive securities:
Convertible preferred stock	[1]	82,993	563,044	994,745
Stock options		11,410	17,828	18,186
Weighted average common shares after assumed conversions		25,380,302	25,387,033	25,381,047
Amounts per common share:
Basic net income per common share		¥ 14.33	¥ 34.19	¥ 32.75
Diluted net income per common share		¥ 14.28	¥ 33.50	¥ 31.64
[1]	The number of common shares after assumed conversion of the convertible preferred stock is based on the applicable conversion prices.

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Current:
Domestic	¥ 130,164	¥ 162,408	¥ 184,180
Foreign	68,512	61,009	71,250
Total current tax expense	198,676	223,417	255,430
Deferred:
Domestic	(99,831)	127,185	187,134
Foreign	(7,601)	(4,060)	(5,144)
Total deferred tax expense	(107,432)	123,125	181,990
Income tax expense	¥ 91,244	¥ 346,542	¥ 437,420

Income Taxes (Tax Effects of It

Income Taxes (Tax Effects of Items Recorded Directly in Equity) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Net unrealized gains (losses) on available-for-sale securities:
Unrealized gains (losses)	¥ 112,467	¥ (97,339)	¥ 403,690
Less: reclassification adjustments	(97,729)	(65,207)	(65,699)
Total	14,738	(162,546)	337,991
Foreign currency translation adjustments:
Unrealized gains (losses)		126
Less: reclassification adjustments	0	0	0
Total		126
Pension liability adjustments:
Unrealized gains (losses)	4,785	(51,661)	87,654
Less: reclassification adjustments	178	(1,317)	(16)
Total	4,963	(52,978)	87,638
Total tax effect before allocation to noncontrolling interests	¥ 19,701	¥ (215,398)	¥ 425,629

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	12 Months Ended
	Mar. 31, 2017		Mar. 31, 2016		Mar. 31, 2015
Reconciliation of Income Tax Expense Benefit and Statutory Federal Tax Rate [Line Items]
Income before income tax expense	¥ 480,375		¥ 1,196,605		¥ 1,267,653
Effective statutory tax rate	30.86%		33.06%		35.64%
Income tax calculated at the statutory tax rate	¥ 148,244		¥ 395,598		¥ 451,792
Income not subject to tax	(7,521)		(12,888)		(20,911)
Expenses not deductible for tax purposes	1,483		1,521		1,532
Tax rate differentials of subsidiaries	(2,165)		(2,208)		(3,517)
Change in valuation allowance	112,781	[1]	(1,897)		(4,444)
Change in undistributed earnings of subsidiaries	5,217		(16,112)		16,084
Change in net operating loss carryforwards resulting from intercompany capital transactions	647		(1,446)		(1,290)
Effect of enacted change in tax rates			(7,976)	[2]	(21,714)	[3]
Reversal of outside basis differences	(159,119)	[1]
Other	(8,323)		(8,050)		19,888
Income tax expense	¥ 91,244		¥ 346,542		¥ 437,420
[1]	These amounts for the fiscal year ended March 31, 2017 represent mainly the reversal of an outside basis difference related to certain foreign subsidiaries due to their organizational restructuring and the related increase in the valuation allowance.
[2]	On March 29, 2016, the National Diet of Japan approved a bill affecting the statutory tax rates of MHFG and its domestic subsidiaries. As a result, the statutory tax rate in respect of MHFG's tax returns for the fiscal year ended March 31, 2017 was reduced to 30.86% from the previous rate of 32.26%, and the statutory tax rate for the fiscal year ending March 31, 2018 will be the same rate. In addition, the tax rate for the fiscal years ending March 31, 2019 and thereafter will be 30.62%. The decrease in the Group's balance of net deferred tax liabilities, reflecting such tax rate reductions, was recognized as a reduction to Income tax expense in the fiscal year ended March 31, 2016.
[3]	On March 31, 2015, the National Diet of Japan approved a bill affecting the statutory tax rates of MHFG and its domestic subsidiaries. As a result, the statutory tax rate in respect of MHFG's tax returns for the fiscal year ended March 31, 2016 was reduced to 33.06% from the previous rate of 35.64%. In addition, the tax rate for the fiscal years ended March 31, 2017 and thereafter was reduced to 32.26%. The decrease in the MHFG Group's balance of net deferred tax liabilities, reflecting such tax rate reductions, was recognized as a reduction to Income tax expense in the fiscal year ended March 31, 2015.

Income Taxes (Reconciliation133

Income Taxes (Reconciliation of Income Tax Expense at Effective Statutory Tax Rate to Actual Income Tax Expense) (Parenthetical) (Detail)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Reconciliation of Income Tax Expense Benefit and Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate	30.86%	33.06%	35.64%
March 31, 2016
Reconciliation of Income Tax Expense Benefit and Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate			33.06%
March 31, 2017
Reconciliation of Income Tax Expense Benefit and Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate		30.86%
March 31, 2017 and Thereafter
Reconciliation of Income Tax Expense Benefit and Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate			32.26%
March 31, 2018
Reconciliation of Income Tax Expense Benefit and Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate		32.26%
March 31, 2019 and Thereafter
Reconciliation of Income Tax Expense Benefit and Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate		30.62%

Income Taxes (Components of Net

Income Taxes (Components of Net Deferred Tax Assets (Liabilities)) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017		Mar. 31, 2016		Mar. 31, 2015	Mar. 31, 2014
Deferred tax assets:
Investments		¥ 497,629		¥ 522,197
Allowance for loan losses		184,366		178,683
Trading securities		30,841
Derivative financial instruments		14,537
Premises and equipment		3,594
Net operating loss carryforwards	[1],[2]	452,166		341,572
Other		190,083		170,414
Deferred Tax Assets, Gross, Total		1,373,216		1,212,866
Valuation allowance		(438,344)	[1]	(339,922)	[1]	¥ (388,551)	¥ (443,847)
Deferred tax assets, net of valuation allowance		934,872		872,944
Deferred tax liabilities:
Available-for-sale securities		724,160		710,497
Prepaid pension cost and accrued pension liabilities		195,620		174,959
Undistributed earnings of subsidiaries		17,161		11,944
Derivative financial instruments				56,877
Trading securities				23,154
Premises and equipment				1,033
Other		74,886		38,990
Deferred tax liabilities		1,011,827		1,017,454
Net deferred tax assets (liabilities)		¥ (76,955)		¥ (144,510)
[1]	The amount includes ¥115,698 million related to MHSC's net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2017. The tax effect of the net operating loss carryforwards is substantially offset by ¥90,204 million 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]	The amount includes ¥268,544 million and ¥271,266 million related to MHFG's net operating loss carryforwards resulting mainly from intercompany capital transactions as of March 31, 2016 and 2017, respectively. The tax effect of the net operating loss carryforwards is offset by a full valuation allowance because MHFG experienced a significant expiration of net operating loss carryforwards of ¥1,262 billion in March 2013, which is negative evidence outweighing any positive evidence. Furthermore, MHFG is a holding company whose primary sources of future taxable income are management fees from subsidiaries that are not sufficient to realize deferred tax assets related to the net operating loss carryforwards.

Income Taxes (Components of 135

Income Taxes (Components of Net Deferred Tax Assets (Liabilities)) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017		Mar. 31, 2016		Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Net operating loss carryforwards	[1],[2]	¥ 452,166		¥ 341,572
Valuation allowance		438,344	[1]	339,922	[1]	¥ 388,551	¥ 443,847
Parent Company
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Net operating loss carryforwards		271,266		¥ 268,544
Net operating loss carryforwards expired								¥ 1,262,000
Mizuho Securities Company Limited
Schedule of Deferred Income Tax Assets and Liabilities [Line Items]
Net operating loss carryforwards		115,698
Valuation allowance		¥ 90,204
[1]	The amount includes ¥115,698 million related to MHSC's net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2017. The tax effect of the net operating loss carryforwards is substantially offset by ¥90,204 million 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]	The amount includes ¥268,544 million and ¥271,266 million related to MHFG's net operating loss carryforwards resulting mainly from intercompany capital transactions as of March 31, 2016 and 2017, respectively. The tax effect of the net operating loss carryforwards is offset by a full valuation allowance because MHFG experienced a significant expiration of net operating loss carryforwards of ¥1,262 billion in March 2013, which is negative evidence outweighing any positive evidence. Furthermore, MHFG is a holding company whose primary sources of future taxable income are management fees from subsidiaries that are not sufficient to realize deferred tax assets related to the net operating loss carryforwards.

Income Taxes (Breakdown of Net

Income Taxes (Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017		Mar. 31, 2016
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[1],[2]	¥ 452,166		¥ 341,572
Operating loss, Valuation allowance		(414,000)		(334,000)
Deferred tax assets,Operating loss carryforward net of valuation allowance		38,000		8,000
Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		388,000	[3]	270,000	[4]
Operating loss, Valuation allowance		(362,000)	[3]	(270,000)	[4]
Deferred tax assets,Operating loss carryforward net of valuation allowance	[3]	26,000
United States of America
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		15,000		16,000
Operating loss, Valuation allowance		(3,000)		(8,000)
Deferred tax assets,Operating loss carryforward net of valuation allowance		12,000		8,000
United Kingdom
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[5]	46,000		53,000
Operating loss, Valuation allowance	[5]	(46,000)		(53,000)
Others
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		3,000		3,000
Operating loss, Valuation allowance		¥ (3,000)		¥ (3,000)
[1]	The amount includes ¥115,698 million related to MHSC's net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2017. The tax effect of the net operating loss carryforwards is substantially offset by ¥90,204 million 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]	The amount includes ¥268,544 million and ¥271,266 million related to MHFG's net operating loss carryforwards resulting mainly from intercompany capital transactions as of March 31, 2016 and 2017, respectively. The tax effect of the net operating loss carryforwards is offset by a full valuation allowance because MHFG experienced a significant expiration of net operating loss carryforwards of ¥1,262 billion in March 2013, which is negative evidence outweighing any positive evidence. Furthermore, MHFG is a holding company whose primary sources of future taxable income are management fees from subsidiaries that are not sufficient to realize deferred tax assets related to the net operating loss carryforwards.
[3]	¥265 billion of the Japan deferred tax assets of ¥388 billion is related to MHFG, which is offset by a full valuation allowance, and will expire during the fiscal year ending March 31, 2018. In addition, ¥116 billion of the Japan deferred tax assets is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026.
[4]	¥265 billion of the Japan deferred tax assets of ¥270 billion is related to MHFG, which is offset by a full valuation allowance, and will expire during the fiscal year ending March 31, 2018.
[5]	The United Kingdom net operating loss carryforwards may be carried forward indefinitely for the tax purposes.

Income Taxes (Breakdown of N137

Income Taxes (Breakdown of Net Operating Loss Carryforwards by Tax Jurisdiction) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017		Mar. 31, 2016
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	[1],[2]	¥ 452,166		¥ 341,572
Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		388,000	[3]	270,000	[4]
Mizuho Financial Group Inc | Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		¥ 265,000		¥ 265,000
Operating loss carryforwards, expiration date		Mar. 31, 2018		Mar. 31, 2018
Mizuho Securities Company Limited
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		¥ 115,698
Mizuho Securities Company Limited | Japan
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards		¥ 116,000
[1]	The amount includes ¥115,698 million related to MHSC's net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2017. The tax effect of the net operating loss carryforwards is substantially offset by ¥90,204 million 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]	The amount includes ¥268,544 million and ¥271,266 million related to MHFG's net operating loss carryforwards resulting mainly from intercompany capital transactions as of March 31, 2016 and 2017, respectively. The tax effect of the net operating loss carryforwards is offset by a full valuation allowance because MHFG experienced a significant expiration of net operating loss carryforwards of ¥1,262 billion in March 2013, which is negative evidence outweighing any positive evidence. Furthermore, MHFG is a holding company whose primary sources of future taxable income are management fees from subsidiaries that are not sufficient to realize deferred tax assets related to the net operating loss carryforwards.
[3]	¥265 billion of the Japan deferred tax assets of ¥388 billion is related to MHFG, which is offset by a full valuation allowance, and will expire during the fiscal year ending March 31, 2018. In addition, ¥116 billion of the Japan deferred tax assets is related to MHSC, which is substantially offset by a valuation allowance, and will expire during the fiscal year ending March 31, 2026.
[4]	¥265 billion of the Japan deferred tax assets of ¥270 billion is related to MHFG, which is offset by a full valuation allowance, and will expire during the fiscal year ending March 31, 2018.

Income Taxes (Roll-Forward of V

Income Taxes (Roll-Forward of Valuation Allowance) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017		Mar. 31, 2016		Mar. 31, 2015
Valuation Allowance [Line Items]
Balance at beginning of fiscal year	¥ 339,922	[1]	¥ 388,551		¥ 443,847
Changes that directly affected Income tax expense	112,781		(1,897)		(4,444)
Expiration of net operating loss carryforwards	0		0		0
Others	(14,359)		(46,732)		(50,852)
Total	(14,359)		(46,732)		(50,852)
Balance at end of fiscal year	¥ 438,344	[1]	¥ 339,922	[1]	¥ 388,551
[1]	The amount includes ¥115,698 million related to MHSC's net operating loss carryforwards resulting mainly from the organizational restructuring of certain foreign subsidiaries as of March 31, 2017. The tax effect of the net operating loss carryforwards is substantially offset by ¥90,204 million 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 - Additional Infor

Income Taxes - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Income Taxes [Line Items]
Changes that directly affected the Income tax expense	¥ (112,781)	¥ 1,897	¥ 4,444
Others	14,359	46,732	50,852
Net operating loss carryforwards	1,590,000	1,590,000
Unrecognized tax benefits, interest and penalties	675	506	517
Unrecognized tax benefits	¥ 1,867	¥ 1,300	¥ 1,632	¥ 1,691
Japan
Income Taxes [Line Items]
Open tax year	2,008
United States of America
Income Taxes [Line Items]
Open tax year	2,002
United Kingdom
Income Taxes [Line Items]
Open tax year	2,015
Parent Company
Income Taxes [Line Items]
Net operating loss carryforwards	¥ 879,000
Operating loss carryforwards, expiration date	Mar. 31, 2018
Parent Company | Previous Intragroup reorganization
Income Taxes [Line Items]
Net operating loss carryforwards	¥ 865,000
Mizuho Securities Company Limited | Restructuring Charges | Minimum
Income Taxes [Line Items]
Operating loss carryforwards, expiration date	Mar. 31, 2026
Mizuho Securities Company Limited | Organizational Restructuring
Income Taxes [Line Items]
Net operating loss carryforwards	¥ 378,000

Income Taxes (Net Operating Los

Income Taxes (Net Operating Losses Carryforwards by Expiration Date) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net operating loss carryforwards	¥ 1,590,000	¥ 1,590,000
Total unrecognized tax benefits at beginning of fiscal year	1,300	1,632	¥ 1,691
Gross amount of increases (decreases) related to positions taken during prior years	167	(415)	(37)
Gross amount of increases related to positions taken during the current year	409	181	346
Amount of decreases related to settlements			(652)
Foreign exchange translation	(9)	(98)	284
Total unrecognized tax benefits at end of fiscal year	1,867	¥ 1,300	¥ 1,632
2,018
Defined Benefit Plan Disclosure [Line Items]
Net operating loss carryforwards	865,000
2,019
Defined Benefit Plan Disclosure [Line Items]
Net operating loss carryforwards	4,000
2,022
Defined Benefit Plan Disclosure [Line Items]
Net operating loss carryforwards	1,000
2023 and Thereafter
Defined Benefit Plan Disclosure [Line Items]
Net operating loss carryforwards	¥ 720,000

Pension and Other Employee B141

Pension and Other Employee Benefit Plans - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plans, costs recognized in respect of contributions to the plans	¥ 3,141	¥ 2,820	¥ 2,444
Amounts in accumulated other comprehensive income (loss) expected to be amortized as prior service cost or benefits over the next fiscal year	180
Amounts in accumulated other comprehensive income (loss) expected to be amortized as actuarial loss over the next fiscal year	417
Increase of benefit obligations	79,861
Pension plan, contribution expected to be paid during the next fiscal year	¥ 51,000

Pension and Other Employee B142

Pension and Other Employee Benefit Plans (Components of Net Periodic Cost of Severance Indemnities and Pension Plans) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost-benefits earned during the fiscal year	¥ 44,367	¥ 38,032	¥ 33,578
Interest costs on projected benefit obligations	5,724	10,479	13,060
Expected return on plan assets	(35,969)	(40,603)	(38,087)
Amortization of prior service benefits	(195)	(195)	(195)
Amortization of net actuarial loss (gain)	780	(4,108)	150
Special termination benefits	3,857	4,456	5,504
Net periodic benefit cost	¥ 18,564	¥ 8,061	¥ 14,010

Pension and Other Employee B143

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, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain (loss)	¥ 15,645	¥ (160,132)
Amortization of net actuarial loss (gain)	780	(4,108)
Amortization of prior service benefits	(195)	(195)
Total recognized in other comprehensive income (loss) before-tax	¥ 16,230	¥ (164,435)

Pension and Other Employee B144

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, 2017	Mar. 31, 2016	Mar. 31, 2015
Weighted-average assumptions used to determine benefit obligations at fiscal year end:
Discount rates	0.47%	0.37%	0.76%
Minimum
Weighted-average assumptions used to determine benefit obligations at fiscal year end:
Rates of increase in future compensation levels	1.80%	1.80%	2.00%
Weighted-average assumptions used to determine net periodic benefit cost during the year:
Rates of increase in future compensation levels	1.80%	2.00%	2.00%
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:
Discount rates	0.37%	0.76%	0.96%
Rates of increase in future compensation levels	4.80%	4.80%	4.80%
Expected rates of return on plan assets	1.73%	1.95%	2.17%

Pension and Other Employee B145

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, 2017		Mar. 31, 2016		Mar. 31, 2015
Change in benefit obligations:
Benefit obligations at beginning of fiscal year	¥ 1,495,208	[1]	¥ 1,392,459
Service cost	44,367		38,032		¥ 33,578
Interest cost	5,724		10,479		13,060
Plan participants' contributions	1,215		1,192
Actuarial loss (gain)	67,335		125,122
Foreign exchange translation	(2,159)		(4,054)
Benefits paid	(51,899)		(51,392)
Lump-sum payments	(13,898)		(16,630)
Benefit obligations at end of fiscal year	1,545,893	[1]	1,495,208	[1]	1,392,459
Change in plan assets:
Fair value of plan assets at beginning of fiscal year	2,082,996		2,081,600
Actual return (negative return) on plan assets	118,714		5,058
Foreign exchange translation	(3,273)		(3,312)
Employer contributions	53,059		49,850
Plan participants' contributions	1,215		1,192
Benefits paid	(51,899)		(51,392)
Fair value of plan assets at end of fiscal year	2,200,812		2,082,996		¥ 2,081,600
Funded status	654,919		587,788
Amounts recognized in the consolidated balance sheets consist of:
Prepaid pension cost	682,592		612,102
Accrued pension liability	(27,673)		(24,314)
Net amount recognized	654,919		587,788
Amounts recognized in Accumulated other comprehensive income (loss) before-tax consist of:
Prior service benefits (cost)	(1,220)		(1,025)
Net actuarial gain (loss)	74,044		57,619
Net amount recognized	¥ 72,824		¥ 56,594
[1]	The aggregated accumulated benefit obligations of these plans were ¥1,493,393 million and ¥1,544,039 million, as of March 31, 2016 and 2017, respectively. The defined benefit plans generally employ a multi-variable and non-linear formula based upon rank and years of service. Employees with service in excess of one year are qualified to receive lump-sum severance indemnities.

Pension and Other Employee B146

Pension and Other Employee Benefit Plans (Combined Funded Status and Amounts Recognized in Accompanying Consolidated Balance Sheets) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Aggregated accumulated benefit obligations	¥ 1,544,039	¥ 1,493,393
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 and Other Employee B147

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, 2017	Mar. 31, 2016
Plans with projected benefit obligations in excess of plan assets:
Projected benefit obligations	[1]	¥ 57,980	¥ 50,554
Fair value of plan assets		30,306	26,240
Plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligations		56,125	48,738
Fair value of plan assets		¥ 30,306	¥ 26,240
[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 B148

Pension and Other Employee Benefit Plans (Target Allocation for Plan Assets Excluding those of Employee Retirement Benefit Trusts) (Detail)	12 Months Ended
	Mar. 31, 2016
Asset category
Plan assets	100.00%
General Account Assets
Asset category
Plan assets	14.00%	[1]
Other assets
Asset category
Plan assets	2.00%
Japan | Equity securities
Asset category
Plan assets	5.00%
Japan | Debt securities
Asset category
Plan assets	44.00%
Foreign | Equity securities
Asset category
Plan assets	25.00%
Foreign | Debt securities
Asset category
Plan assets	10.00%
[1]	General account of life insurance companies is a contract with life insurance companies which guarantees payments of principal and predetermined interest rates.

Pension and Other Employee B149

Pension and Other Employee Benefit Plans (Fair Value of Plan Assets by Asset Category) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Dec. 31, 2016		Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		¥ 2,200,812	¥ 2,083,000		¥ 2,082,996	¥ 2,081,600
Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[1]	338,000	303,000
General account of life insurance companies
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[2]	124,000	121,000
Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		79,000	40,000
Japan | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[3]	1,162,000	1,115,000
Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	10,000	11,000
Japan | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	2,000	1,000
Japan | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		254,000	262,000
Japan | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		25,000	32,000
Foreign | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		111,000	98,000
Foreign | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	2,000	2,000
Foreign | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	7,000	8,000
Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		71,000	74,000
Foreign | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		16,000	16,000
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		1,683,000	1,600,000
Level 1 | Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		78,000	44,000	[5]
Level 1 | Japan | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[3]	1,162,000	1,114,000
Level 1 | Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	10,000	10,000
Level 1 | Japan | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		254,000	262,000
Level 1 | Foreign | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		111,000	98,000
Level 1 | Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		68,000	72,000
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		180,000	180,000
Level 2 | General account of life insurance companies
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[2]	124,000	121,000
Level 2 | Other Invested Assets
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		1,000	(4,000)	[6]
Level 2 | Japan | Common stocks | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[3]		1,000
Level 2 | Japan | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]		1,000
Level 2 | Japan | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	2,000	1,000
Level 2 | Japan | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		25,000	32,000
Level 2 | Foreign | Pooled funds | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	2,000	2,000
Level 2 | Foreign | Pooled funds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	[4]	7,000	8,000
Level 2 | Foreign | Government bonds | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		3,000	2,000
Level 2 | Foreign | Other | Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets		¥ 16,000	¥ 16,000
[1]	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.
[2]	Investments in this class are measured at conversion value.
[3]	This class represents equity securities held in the employee retirement benefit trusts of ¥1,115 billion and ¥1,162 billion at March 31, 2016 and 2017, respectively, which are well-diversified across industries.
[4]	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.
[5]	Amounts primarily include cash and short-term assets carried at fair value.
[6]	Amounts primarily include foreign exchange contracts carried at fair value.

Pension and Other Employee B150

Pension and Other Employee Benefit Plans (Fair Value of Plan Assets by Asset Category) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts		¥ 2,200,812	¥ 2,083,000	¥ 2,082,996	¥ 2,081,600
Japan | Equity securities | Common stocks
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts	[1]	1,162,000	¥ 1,115,000
Trust for Benefit of Employees | Japan | Equity securities | Common stocks
Defined Benefit Plan Disclosure [Line Items]
Equity securities held in the employee retirement benefit trusts		¥ 1,162,000		¥ 1,115,000
[1]	This class represents equity securities held in the employee retirement benefit trusts of ¥1,115 billion and ¥1,162 billion at March 31, 2016 and 2017, respectively, which are well-diversified across industries.

Pension and Other Employee B151

Pension and Other Employee Benefit Plans (Forecasted Benefit Payments Including Effect of Expected Future Service) (Detail) ¥ in Millions	Mar. 31, 2016JPY (¥)
Defined Benefit Plan Disclosure [Line Items]
2,018	¥ 66,140
2,019	67,758
2,020	69,578
2,021	70,808
2,022	71,549
2023-2027	¥ 354,180

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - JPY (¥) ¥ / shares in Units, ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation plan, exercise price per share	¥ 0
Stock-based compensation plan, weighted-average grant-date fair value		¥ 186,990
Stock-based compensation plan, compensation cost recognized in income	¥ 354	¥ 1,795
Performance-based stock compensation, recognition period	2 years 3 months 19 days
Compensation cost related to non-vested awards not yet recognized	¥ 1,074
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of common stock acquired from the stock market	¥ 1,428
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	1,000
Stock-based compensation plan, exercise price per share	¥ 1
Stock-based compensation plan, contractual term (in years)	20 years
Performance-based stock compensation, recognition period	3 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, 2017JPY (¥)¥ / sharesshares
Number of shares
Outstanding at beginning of fiscal year | shares	17,190,000
Exercised during fiscal year | shares	6,371,000
Outstanding at end of fiscal year | shares	10,819,000
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	16 years 5 months 27 days
Exercisable at end of fiscal year	0 years
Aggregate intrinsic value
Outstanding at end of fiscal year | ¥	¥ 2,196
Exercisable at end of fiscal year | ¥	¥ 0

Stock-Based Compensation (Assum

Stock-Based Compensation (Assumptions to Estimate Fair Value of Stock Acquisition Rights on Date of Grant Used in Black-Scholes Option Pricing Model) (Detail)	12 Months Ended
	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.01%
Expected volatility	25.91%
Expected remaining term (in years)	2 years 5 months 16 days
Expected dividend yield	3.42%

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Activities Related to Performance-based Stock Compensation (Detail)	12 Months Ended
	Mar. 31, 2017¥ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at beginning of fiscal year	17,190,000
Outstanding at end of fiscal year	10,819,000
Performance-based stock compensation
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, Granted during fiscal year	9,000,000
Number of shares, Vested during fiscal year	0
Number of shares, Forfeited during fiscal year	0
Outstanding at end of fiscal year	9,000,000
Weighted-average grant-date fair value, Granted during fiscal year | ¥ / shares	¥ 158.68
Weighted-average grant-date fair value, Vested during fiscal year | ¥ / shares	0
Weighted-average grant-date fair value, Forfeited during fiscal year | ¥ / shares	0
Weighted-average grant-date fair value, Outstanding ending balance | ¥ / shares	¥ 158.68

Derivative Financial Instrum156

Derivative Financial Instruments (Notional and Fair Value Amounts of Derivative Instruments Outstanding) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2017	Mar. 31, 2016
Derivatives, Fair Value [Line Items]
Notional amount	[1]	¥ 1,137,449	¥ 1,216,037
Interest rate contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	961,518	1,066,252
Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	167,698	141,517
Equity-related contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	4,177	3,115
Credit-related contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	3,696	4,826
Other contracts
Derivatives, Fair Value [Line Items]
Notional amount	[1]	360	327
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	2	22
Fair value of derivative payables	[2]	5	1
Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	2	4
Fair value of derivative payables	[2]		1
Designated as Hedging Instrument | Equity-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]		18
Fair value of derivative payables	[2]	5
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	11,441	14,902
Fair value of derivative payables	[2]	11,366	14,480
Not Designated as Hedging Instrument | Interest rate contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	8,506	11,522
Fair value of derivative payables	[2]	8,473	11,269
Not Designated as Hedging Instrument | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	2,743	3,126
Fair value of derivative payables	[2]	2,611	2,979
Not Designated as Hedging Instrument | Equity-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	134	152
Fair value of derivative payables	[2]	224	140
Not Designated as Hedging Instrument | Credit-related contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	35	43
Fair value of derivative payables	[2]	36	37
Not Designated as Hedging Instrument | Other contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative receivables	[2]	23	59
Fair value of derivative payables	[2]	¥ 22	¥ 55
[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 Instrum157

Derivative Financial Instruments - Additional Information (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016
Derivative [Line Items]
Cash collateral provided and not offset against derivative positions and included in Other assets	¥ 973,404	¥ 884,651
Cash collateral accepted and not offset against derivative positions and included in Other liabilities	¥ 671,691	¥ 715,894

Derivative Financial Instrum158

Derivative Financial Instruments (Gains and Losses Information Related to Fair Value Hedges) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income- Derivatives	¥ (14,747)	¥ 14,623	¥ (29,666)
Gains (losses) recorded in income- Hedged items	11,393	(18,224)	28,005
Gains (losses) recorded in income- Hedge ineffectiveness	0	0	0
Gains (losses) recorded in income- Net gain (loss) excluded from assessment of effectiveness	(3,354)	(3,601)	(1,661)
Equity-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income- Derivatives	(14,747)	14,623	(29,666)
Gains (losses) recorded in income- Hedged items	11,393	(18,224)	28,005
Gains (losses) recorded in income- Hedge ineffectiveness	0	0	0
Gains (losses) recorded in income- Net gain (loss) excluded from assessment of effectiveness	¥ (3,354)	¥ (3,601)	¥ (1,661)

Derivative Financial Instrum159

Derivative Financial Instruments (Gains and Losses Information Related to Net Investment Hedges) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion recorded in OCI	¥ 16,767	¥ 46,697	¥ (53,252)
Ineffective portion recorded in income	47	696	(2,678)
Financial instruments hedging foreign exchange risk
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion recorded in OCI	16,767	46,697	(53,252)
Ineffective portion recorded in income	¥ 47	¥ 696	¥ (2,678)

Derivative Financial Instrum160

Derivative Financial Instruments (Gains and Losses Information Related to Net Investment Hedges) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Financial instruments hedging foreign exchange risk
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income reclassified to earnings	¥ 41	¥ 345	¥ 0

Derivative Financial Instrum161

Derivative Financial Instruments (Gains and Losses on Derivatives Not Designated or Qualifying as Hedges) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ (173,053)	¥ 400,952	¥ 53,758
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		(209,361)	319,225	265,324
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		37,129	65,101	(93,601)
Equity-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[1]	5,131	21,571	(100,326)
Credit-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[2]	(6,694)	(6,960)	(18,007)
Other contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ 742	¥ 2,015	¥ 368
[1]	The net gain (loss) excluded from the assessment of the effectiveness of fair value hedges is not included in the above table.
[2]	Amounts include the net loss of ¥2,836 million, ¥5,230 million and ¥7,594 million on the credit derivatives hedging the credit risk of loans during the fiscal years ended March 31, 2015, 2016 and 2017, respectively.

Derivative Financial Instrum162

Derivative Financial Instruments (Gains and Losses on Derivatives Not Designated or Qualifying as Hedges) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ (173,053)	¥ 400,952	¥ 53,758
Credit-related contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income	[1]	(6,694)	(6,960)	(18,007)
Credit-related contracts | Loans related to credit derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) recorded in income		¥ (7,594)	¥ (5,230)	¥ (2,836)
[1]	Amounts include the net loss of ¥2,836 million, ¥5,230 million and ¥7,594 million on the credit derivatives hedging the credit risk of loans during the fiscal years ended March 31, 2015, 2016 and 2017, respectively.

Derivative Financial Instrum163

Derivative Financial Instruments (Notional and Fair Value Amounts of Credit Derivatives) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Credit protection written
Credit Derivatives [Line Items]
Notional amount	¥ 1,844	¥ 2,366
Fair value	22	15
Credit protection written | Investment grade
Credit Derivatives [Line Items]
Notional amount	1,546	1,603
Fair value	21	14
Credit protection written | Non-investment grade
Credit Derivatives [Line Items]
Notional amount	298	763
Fair value	1	1
Credit protection purchased
Credit Derivatives [Line Items]
Notional amount	1,994	2,592
Fair value	¥ (23)	¥ (9)

Derivative Financial Instrum164

Derivative Financial Instruments (Maximum Potential Amount of Future Payments for Credit Protection Written by Expiration Period) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Credit Derivatives [Line Items]
Maximum payout/Notional amount	¥ 1,844	¥ 2,366
One year or less
Credit Derivatives [Line Items]
Maximum payout/Notional amount	507	538
After one year through five years
Credit Derivatives [Line Items]
Maximum payout/Notional amount	1,020	1,729
After five years
Credit Derivatives [Line Items]
Maximum payout/Notional amount	¥ 317	¥ 99

Derivative Financial Instrum165

Derivative Financial Instruments (Aggregate Fair Value of Derivative Instruments) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Credit Derivatives [Line Items]
Aggregate fair value of derivative instruments with credit-risk-related contingent features in net liability positions	¥ 698	¥ 790
Collateral provided to counterparties in the normal course of business	658	746
Amount required to be posted as collateral or settled immediately if credit-risk-related contingent features were triggered	¥ 40	¥ 44

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Commitments and Contingencies Disclosure [Line Items]
Carrying amount of guarantees and similar obligations	¥ 249,000	¥ 357,000
Carrying amounts of derivatives that are deemed to guarantees	228,000	336,000
Total rental expense	¥ 113,991	118,400	¥ 109,390
Sale Leaseback transactions accounted as an operating leases, minimum lease back periods	5 years
Sale Leaseback transactions accounted as an operating leases, maximum lease back periods	10 years
Sale Leaseback transactions accounted as an operating leases, total rental payment for the whole period in the original contracts	¥ 214,690
Sale Leaseback transactions accounted as an operating leases, total rental payment for the whole period in the current contracts	282,832
Sale Leaseback transactions accounted as an operating leases, future minimum rental payments	41,430	49,883	¥ 58,336
Off-balance Sheet instruments
Commitments and Contingencies Disclosure [Line Items]
Allowance for losses on off-balance-sheet instruments	¥ 120,000	¥ 100,000

Commitments and Contingencie167

Commitments and Contingencies (Maximum Exposure or Notional Amount Under Guarantee Contracts) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	¥ 2,243	¥ 2,110
Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	278	297
Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	175	203
Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	1,823	1,571
Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	730	1,141
Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	15,177	12,747
Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	14,415	15,792
One year or less | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	1,246	1,049
One year or less | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	147	117
One year or less | Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	37	67
One year or less | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	1,246	1,206
One year or less | Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	654	1,051
One year or less | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	14,927	12,537
One year or less | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	6,066	6,505
After one year through five years | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	828	909
After one year through five years | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	20	20
After one year through five years | Guarantees on securities
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	138	136
After one year through five years | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	513	325
After one year through five years | Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	52	63
After one year through five years | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	82	79
After one year through five years | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	6,603	8,032
After five years | Performance guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	169	152
After five years | Guarantees on loans
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	111	160
After five years | Other guarantees
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	64	40
After five years | Guarantees for repayment of trust principal
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	24	27
After five years | Liabilities of trust accounts
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	168	131
After five years | Derivative financial instruments
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	¥ 1,746	¥ 1,255

Commitments and Contingencie168

Commitments and Contingencies (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, 2017	Mar. 31, 2016
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount		¥ 4,519	¥ 4,182
Investment grade
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount	[1]	3,477	3,160
Non-investment grade
Guarantor Obligations [Line Items]
Maximum potential/Contractual or Notional amount		¥ 1,042	¥ 1,022
[1]	Investment grade in the internal rating scale generally corresponds to BBB- or above in the external rating scale.

Commitments and Contingencie169

Commitments and Contingencies (Contractual Amounts With Regard to Undrawn Commitments) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2017	Mar. 31, 2016
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments		¥ 77,200	¥ 76,190
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]	76,678	75,742
Commercial letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Off-balance-sheet instruments, contractual amounts of the undrawn commitments		¥ 522	¥ 448
[1]	Commitments to extend credit include commitments to invest in securities.

Commitments and Contingencie170

Commitments and Contingencies (Future Minimum Lease Payments for Capitalized Leases and Rental Payments for Operating Leases) (Detail) ¥ in Millions	Mar. 31, 2017JPY (¥)
Capitalized leases
2,018	¥ 11,519
2,019	10,721
2,020	8,697
2,021	6,118
2,022	3,188
2023 and thereafter	1,846
Total minimum lease/rental payments	42,089
Amount representing interest	1,142
Present value of minimum lease payments	40,947
Operating leases
2,018	52,280
2,019	46,330
2,020	41,157
2,021	35,291
2,022	30,562
2023 and thereafter	57,787
Total minimum lease/rental payments	¥ 263,407

Variable Interest Entities a171

Variable Interest Entities and Securitizations (Consolidated Assets of Groups Consolidated VIEs as well as Total Assets and Maximum Exposure to Loss for Its Significant Unconsolidated VIEs) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	¥ 5,246	¥ 4,692
Significant unconsolidated VIEs- Total assets	4,448	3,072
Significant unconsolidated VIEs- Maximum exposure to loss	628	534
Asset-backed commercial paper/loan programs
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	2,031	2,092
Asset-backed securitizations
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	629	579
Significant unconsolidated VIEs- Total assets	108	205
Significant unconsolidated VIEs- Maximum exposure to loss	11	13
Investments in securitization products
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	375	337
Significant unconsolidated VIEs- Total assets	445	445
Significant unconsolidated VIEs- Maximum exposure to loss	154	154
Investment funds
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	2,188	1,660
Significant unconsolidated VIEs- Total assets	3,895	2,422
Significant unconsolidated VIEs- Maximum exposure to loss	463	367
Trust arrangements and other
Variable Interest Entity [Line Items]
Consolidated VIEs- Consolidated assets	¥ 23	¥ 24

Variable Interest Entities a172

Variable Interest Entities and Securitizations (Carrying Amounts and Classification of Assets and Liabilities on MHFG Group's Balance Sheets that Relate to its Variable Interests in Significant Unconsolidated VIEs) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Assets on balance sheets related to unconsolidated VIEs:
Trading account assets		¥ 24,998,493	¥ 30,020,743
Loans		81,804,233	77,104,122
Total		200,456,304	193,810,151	¥ 190,114,400
Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs:
Payables under securities lending transactions		1,919,249	2,844,653
Trading account liabilities		13,591,740	17,111,142
Total		191,684,247	185,626,960
Maximum exposure to loss		628,000	534,000
Unconsolidated VIEs
Assets on balance sheets related to unconsolidated VIEs:
Trading account assets		85,000	55,000
Investments		254,000	254,000
Loans		237,000	205,000
Total		576,000	514,000
Liabilities on balance sheets and maximum exposure to loss related to unconsolidated VIEs:
Payables under securities lending transactions		31,000	27,000
Trading account liabilities		1,000	1,000
Total		32,000	28,000
Maximum exposure to loss	[1]	¥ 628,000	¥ 534,000
[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 a173

Variable Interest Entities and Securitizations - Additional Information (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Apr. 01, 2016	Mar. 31, 2016	Mar. 31, 2015
Variable Interest Entity [Line Items]
Total assets	¥ 200,456,304		¥ 193,810,151	¥ 190,114,400
Noncontrolling interests	510,700		168,640
Total liabilities	191,684,247		185,626,960
Consolidated certain investment funds | Restatement Adjustment
Variable Interest Entity [Line Items]
Total assets		¥ 16,000
Noncontrolling interests		16,000
Deconsolidated certain investment funds | Restatement Adjustment
Variable Interest Entity [Line Items]
Total assets		(54,000)
Noncontrolling interests		(27,000)
Total liabilities		¥ (27,000)
Assets associated with securitization transactions
Variable Interest Entity [Line Items]
Transferred assets continue to be carried on the consolidated balance sheets	244,000		243,000
Assets associated with loan participation transactions
Variable Interest Entity [Line Items]
Transferred assets continue to be carried on the consolidated balance sheets	¥ 91,000		¥ 64,000

Fee and Commission Income (Deta

Fee and Commission Income (Details of Fees and Commission Income) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Principal Transaction Revenue [Line Items]
Securities-related business	¥ 165,857	¥ 175,723	¥ 172,234
Deposits and lending business	164,573	143,763	131,491
Remittance business	108,368	109,859	110,181
Trust fees	47,379	50,496	49,827
Fees for other customer services	260,360	263,112	251,924
Total	¥ 746,537	¥ 742,953	¥ 715,657

Fee and Commission Income - Add

Fee and Commission Income - Additional Information (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Principal Transaction Revenue [Line Items]
Fee and commission related to assets management business	¥ 746,537	¥ 742,953	¥ 715,657
Assets Management Business
Principal Transaction Revenue [Line Items]
Fee and commission related to assets management business	¥ 79,426	¥ 61,803	¥ 57,998

Trading Account Gains and Lo176

Trading Account Gains and Losses (Net Trading Gains and Losses) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)-net		¥ (42,481)	¥ 559,139	¥ 689,959
Foreign exchange gains (losses)-net	[1]	69,453	113,553	(34,520)
Net trading gains (losses)		26,972	672,692	655,439
Interest rate contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)-net	[2]	(209,361)	319,225	265,324
Foreign exchange contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)-net		37,129	65,101	(93,601)
Equity-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)-net	[2]	1,777	17,970	(101,988)
Credit-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)-net	[3]	900	(1,731)	(15,171)
Other contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)-net		742	2,015	368
Trading securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading account gains (losses)-net		¥ 126,332	¥ 156,559	¥ 635,027
[1]	Amounts include realized and unrealized gains and losses on both derivative instruments and nonderivative instruments, such as translation gains and losses related to foreign currency-denominated available-for-sale securities for which the fair value option has been elected in accordance with ASC 825.
[2]	The net gain (loss) excluded from the assessment of the effectiveness of fair value hedges is included in the above table.
[3]	Amounts do not include the net loss of ¥2,836 million, ¥5,230 million and ¥7,594 million on the credit derivatives hedging the credit risk of loans during the fiscal years ended March 31, 2015, 2016 and 2017, respectively. The net loss is recorded in Other noninterest expenses.

Trading Account Gains and Lo177

Trading Account Gains and Losses (Net Trading Gains and Losses) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income		¥ (173,053)	¥ 400,952	¥ 53,758
Credit-related contracts
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income	[1]	(6,694)	(6,960)	(18,007)
Credit-related contracts | Loans related to credit derivatives
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gains (losses) recorded in income		¥ (7,594)	¥ (5,230)	¥ (2,836)
[1]	Amounts include the net loss of ¥2,836 million, ¥5,230 million and ¥7,594 million on the credit derivatives hedging the credit risk of loans during the fiscal years ended March 31, 2015, 2016 and 2017, respectively.

Fair Value - Additional Informa

Fair Value - Additional Information (Detail) - JPY (¥) ¥ in Billions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Carrying amounts of other equity interests of which fair value is not readily determinable	¥ 308	¥ 313
Senior borrowings and bonds
Fair Value, Estimate Not Practicable, Financial Statement Captions [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	36	20
Net unrealized gains (losses) resulting from changes in fair values of the notes	¥ 16	14
Investment funds
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Underlying assets, estimated remaining liquidation period	10 years
Long-term debt
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair value of liabilities transferred into Level 3	¥ 21	8
Fair value of liabilities transferred out of Level 3	12
Trading securities sold, not yet purchased
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair value of liabilities transferred into Level 3	1
Trading securities
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair value of assets transferred into Level 3	296	25
Fair value of assets transferred out of Level 3	39	34
Available-for-sale securities
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Fair value of assets transferred into Level 3		¥ 23
Fair value of assets transferred out of Level 3	¥ 2

Fair Value (Assets and Liabilit

Fair Value (Assets and Liabilities Measured at Fair Value on Recurring Basis Including those for Which MHFG Group has Elected Fair Value Option) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Assets:
Available-for-sale securities		¥ 20,557,118	¥ 25,452,525
Liabilities:
Long-term debt		1,496,488	1,055,626
Fair Value, Measurements, Recurring
Assets:
Other investments		37,000	42,000
Total assets measured at fair value	[1]	45,592,000	55,516,000
Liabilities:
Trading securities sold, not yet purchased		2,221,000	2,630,000
Long-term debt	[2]	1,496,000	1,056,000
Total liabilities measured at fair value		15,088,000	18,167,000
Fair Value, Measurements, Recurring | Trading securities
Assets:
Securities measured at net asset value	[1]	678,000	617,000
Fair Value, Measurements, Recurring | Interest rate contracts
Assets:
Assets, derivatives		8,506,000	11,522,000
Liabilities:
Liabilities, derivatives		8,473,000	11,269,000
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets:
Assets, derivatives		2,745,000	3,130,000
Liabilities:
Liabilities, derivatives		2,611,000	2,980,000
Fair Value, Measurements, Recurring | Equity-related contracts
Assets:
Assets, derivatives		134,000	170,000
Liabilities:
Liabilities, derivatives		229,000	140,000
Fair Value, Measurements, Recurring | Credit-related contracts
Assets:
Assets, derivatives		35,000	43,000
Liabilities:
Liabilities, derivatives		36,000	37,000
Fair Value, Measurements, Recurring | Other contracts
Assets:
Assets, derivatives		23,000	59,000
Liabilities:
Liabilities, derivatives		22,000	55,000
Fair Value, Measurements, Recurring | Japanese government bonds
Assets:
Assets, trading securities	[3]	1,508,000	2,303,000
Available-for-sale securities		10,263,000	15,763,000
Fair Value, Measurements, Recurring | Japanese local government bonds
Assets:
Assets, trading securities	[3]	69,000	79,000
Available-for-sale securities		284,000	241,000
Fair Value, Measurements, Recurring | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	2,963,000	3,806,000
Available-for-sale securities		1,144,000	438,000
Fair Value, Measurements, Recurring | Other foreign government bonds
Assets:
Assets, trading securities	[3]	1,584,000	2,565,000
Available-for-sale securities		935,000	942,000
Fair Value, Measurements, Recurring | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	1,973,000	1,558,000
Available-for-sale securities		843,000	949,000
Fair Value, Measurements, Recurring | Residential mortgage-backed securities
Assets:
Assets, trading securities	[3]	15,000	21,000
Available-for-sale securities		144,000	210,000
Fair Value, Measurements, Recurring | Commercial mortgage-backed securities
Assets:
Assets, trading securities	[3]	3,000	4,000
Available-for-sale securities		224,000	187,000
Fair Value, Measurements, Recurring | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[3]	554,000	881,000
Fair Value, Measurements, Recurring | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3]	2,504,000	2,422,000
Fair Value, Measurements, Recurring | Equity securities
Assets:
Assets, trading securities	[3]	1,704,000	841,000
Fair Value, Measurements, Recurring | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		2,008,000	2,095,000
Fair Value, Measurements, Recurring | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		911,000	847,000
Fair Value, Measurements, Recurring | Equity securities (marketable)
Assets:
Available-for-sale securities		3,801,000	3,781,000
Fair Value, Measurements, Recurring | Level 1
Assets:
Total assets measured at fair value	[1]	23,475,000	29,833,000
Liabilities:
Trading securities sold, not yet purchased		1,993,000	2,482,000
Total liabilities measured at fair value		2,189,000	2,666,000
Fair Value, Measurements, Recurring | Level 1 | Interest rate contracts
Assets:
Assets, derivatives		37,000	97,000
Liabilities:
Liabilities, derivatives		46,000	98,000
Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Assets:
Assets, derivatives		28,000	23,000
Liabilities:
Liabilities, derivatives		20,000	26,000
Fair Value, Measurements, Recurring | Level 1 | Equity-related contracts
Assets:
Assets, derivatives		31,000	46,000
Liabilities:
Liabilities, derivatives		129,000	60,000
Fair Value, Measurements, Recurring | Level 1 | Other contracts
Assets:
Assets, derivatives		1,000
Liabilities:
Liabilities, derivatives		1,000
Fair Value, Measurements, Recurring | Level 1 | Japanese government bonds
Assets:
Assets, trading securities	[3]	1,485,000	2,272,000
Available-for-sale securities		9,543,000	15,037,000
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	2,883,000	3,729,000
Available-for-sale securities		1,144,000	438,000
Fair Value, Measurements, Recurring | Level 1 | Other foreign government bonds
Assets:
Assets, trading securities	[3]	1,127,000	2,192,000
Available-for-sale securities		346,000	352,000
Fair Value, Measurements, Recurring | Level 1 | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	1,335,000	995,000
Available-for-sale securities		134,000	169,000
Fair Value, Measurements, Recurring | Level 1 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3]	3,000	9,000
Fair Value, Measurements, Recurring | Level 1 | Equity securities
Assets:
Assets, trading securities	[3]	1,661,000	758,000
Fair Value, Measurements, Recurring | Level 1 | Equity securities (marketable)
Assets:
Available-for-sale securities		3,717,000	3,716,000
Fair Value, Measurements, Recurring | Level 2
Assets:
Total assets measured at fair value	[1]	19,665,000	23,561,000
Liabilities:
Trading securities sold, not yet purchased		228,000	148,000
Long-term debt	[2]	903,000	433,000
Total liabilities measured at fair value		12,253,000	14,809,000
Fair Value, Measurements, Recurring | Level 2 | Interest rate contracts
Assets:
Assets, derivatives		8,442,000	11,396,000
Liabilities:
Liabilities, derivatives		8,426,000	11,168,000
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Assets:
Assets, derivatives		2,709,000	3,099,000
Liabilities:
Liabilities, derivatives		2,591,000	2,953,000
Fair Value, Measurements, Recurring | Level 2 | Equity-related contracts
Assets:
Assets, derivatives		89,000	95,000
Liabilities:
Liabilities, derivatives		61,000	56,000
Fair Value, Measurements, Recurring | Level 2 | Credit-related contracts
Assets:
Assets, derivatives		33,000	40,000
Liabilities:
Liabilities, derivatives		34,000	33,000
Fair Value, Measurements, Recurring | Level 2 | Other contracts
Assets:
Assets, derivatives		11,000	21,000
Liabilities:
Liabilities, derivatives		10,000	18,000
Fair Value, Measurements, Recurring | Level 2 | Japanese government bonds
Assets:
Assets, trading securities	[3]	23,000	31,000
Available-for-sale securities		720,000	726,000
Fair Value, Measurements, Recurring | Level 2 | Japanese local government bonds
Assets:
Assets, trading securities	[3]	69,000	79,000
Available-for-sale securities		284,000	241,000
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury bonds and federal agency securities
Assets:
Assets, trading securities	[3]	80,000	77,000
Fair Value, Measurements, Recurring | Level 2 | Other foreign government bonds
Assets:
Assets, trading securities	[3]	457,000	373,000
Available-for-sale securities		589,000	590,000
Fair Value, Measurements, Recurring | Level 2 | Agency mortgage-backed securities
Assets:
Assets, trading securities	[3]	638,000	563,000
Available-for-sale securities		709,000	780,000
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage-backed securities
Assets:
Available-for-sale securities		67,000	87,000
Fair Value, Measurements, Recurring | Level 2 | Commercial mortgage-backed securities
Assets:
Assets, trading securities	[3]	3,000	2,000
Fair Value, Measurements, Recurring | Level 2 | Certificates of deposit and commercial paper
Assets:
Assets, trading securities	[3]	554,000	881,000
Fair Value, Measurements, Recurring | Level 2 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3]	1,449,000	1,693,000
Fair Value, Measurements, Recurring | Level 2 | Equity securities
Assets:
Assets, trading securities	[3]	20,000	62,000
Fair Value, Measurements, Recurring | Level 2 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		1,834,000	1,921,000
Fair Value, Measurements, Recurring | Level 2 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		801,000	739,000
Fair Value, Measurements, Recurring | Level 2 | Equity securities (marketable)
Assets:
Available-for-sale securities		84,000	65,000
Fair Value, Measurements, Recurring | Level 3
Assets:
Other investments		37,000	42,000
Total assets measured at fair value	[1]	1,774,000	1,505,000
Liabilities:
Long-term debt	[2]	593,000	623,000
Total liabilities measured at fair value		646,000	692,000
Fair Value, Measurements, Recurring | Level 3 | Interest rate contracts
Assets:
Assets, derivatives		27,000	29,000
Liabilities:
Liabilities, derivatives		1,000	3,000
Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Assets:
Assets, derivatives		8,000	8,000
Liabilities:
Liabilities, derivatives			1,000
Fair Value, Measurements, Recurring | Level 3 | Equity-related contracts
Assets:
Assets, derivatives		14,000	29,000
Liabilities:
Liabilities, derivatives		39,000	24,000
Fair Value, Measurements, Recurring | Level 3 | Credit-related contracts
Assets:
Assets, derivatives		2,000	3,000
Liabilities:
Liabilities, derivatives		2,000	4,000
Fair Value, Measurements, Recurring | Level 3 | Other contracts
Assets:
Assets, derivatives		11,000	38,000
Liabilities:
Liabilities, derivatives		11,000	37,000
Fair Value, Measurements, Recurring | Level 3 | Residential mortgage-backed securities
Assets:
Assets, trading securities	[3]	15,000	21,000
Available-for-sale securities		77,000	123,000
Fair Value, Measurements, Recurring | Level 3 | Commercial mortgage-backed securities
Assets:
Assets, trading securities	[3]		2,000
Available-for-sale securities		224,000	187,000
Fair Value, Measurements, Recurring | Level 3 | Corporate bonds and other debt securities
Assets:
Assets, trading securities	[3]	1,052,000	720,000
Fair Value, Measurements, Recurring | Level 3 | Equity securities
Assets:
Assets, trading securities	[3]	23,000	21,000
Fair Value, Measurements, Recurring | Level 3 | Japanese corporate bonds and other debt securities
Assets:
Available-for-sale securities		174,000	174,000
Fair Value, Measurements, Recurring | Level 3 | Foreign corporate bonds and other debt securities
Assets:
Available-for-sale securities		¥ 110,000	¥ 108,000
[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, 2016 and 2017 were ¥30 billion and ¥33 billion, respectively.
[2]	Amounts represent items for which the Group elected the fair value option.
[3]	Trading securities include foreign currency denominated securities for which the MHFG Group elected the fair value option.

Fair Value (Assets and Liabi180

Fair Value (Assets and Liabilities Measured at Fair Value on Recurring Basis Including those for Which MHFG Group has Elected Fair Value Option) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unfunded commitments	¥ 33	¥ 30

Fair Value (Reconciliation for

Fair Value (Reconciliation for All Assets and Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs Level 3) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Other investments
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		¥ 42	¥ 53
Gains (losses) in Earnings	[1]		7
Purchases		12	5
Sales		(3)	(20)
Issuances		0	0
Settlements		(14)	(3)
Ending Balance		37	42
Change in unrealized gain (losses) still held	[2]		(7)
Trading securities sold, not yet purchased
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Gains (losses) in OCI		0	0
Transfers into Level 3		1
Purchases		(54)	(5)
Sales		53	5
Long-term debt
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		623	587
Gains (losses) in Earnings	[3]	20	18
Gains (losses) in OCI		0	0
Transfers into Level 3		21	8
Transfers out of level 3		(12)
Purchases		(2)	(1)
Sales		1
Issuances		278	305
Settlements		(296)	(258)
Ending Balance		593	623
Change in unrealized gain (losses) still held	[2]	18	19
Trading securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers into Level 3		296	25
Transfers out of level 3		(39)	(34)
Trading securities | Other foreign government bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Purchases			1
Sales			(1)
Issuances			0
Trading securities | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		21	29
Gains (losses) in Earnings	[4]	(1)
Issuances		0	0
Settlements		(5)	(8)
Ending Balance		15	21
Change in unrealized gain (losses) still held	[2]	(1)
Trading securities | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		2	4
Issuances		0	0
Settlements		(2)	(2)
Ending Balance			2
Trading securities | Corporate bonds and other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		720	639
Gains (losses) in Earnings	[4]	12	(43)
Transfers into Level 3		296	25
Transfers out of level 3		(39)	(34)
Purchases		875	452
Sales		(555)	(192)
Issuances		0	0
Settlements		(257)	(127)
Ending Balance		1,052	720
Change in unrealized gain (losses) still held	[2]	19	(38)
Trading securities | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		21	23
Gains (losses) in Earnings	[4]	1	(3)
Purchases		3	1
Sales		(2)
Issuances		0	0
Ending Balance		23	21
Change in unrealized gain (losses) still held	[2]		(1)
Derivative assets | Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	26	18
Gains (losses) in Earnings	[4],[5]	(2)	(1)
Issuances	[5]	0	0
Settlements	[5]	2	9
Ending Balance	[5]	26	26
Change in unrealized gain (losses) still held	[2],[5]	2	11
Derivative assets | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	7	8
Gains (losses) in Earnings	[4],[5]	7	(1)
Issuances	[5]	0	0
Settlements	[5]	(6)
Ending Balance	[5]	8	7
Change in unrealized gain (losses) still held	[2],[5]	1	(2)
Derivative assets | Equity-related contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	5	(14)
Gains (losses) in Earnings	[4],[5]	(31)	22
Issuances	[5]	0	0
Settlements	[5]	1	(3)
Ending Balance	[5]	(25)	5
Change in unrealized gain (losses) still held	[2],[5]	(35)	14
Derivative assets | Credit-related contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	(1)	(1)
Gains (losses) in Earnings	[4],[5]	1
Issuances	[5]	0	0
Ending Balance	[5]		(1)
Derivative assets | Other contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	[5]	1
Gains (losses) in Earnings	[4],[5]		1
Issuances	[5]	0	0
Settlements	[5]	(1)
Ending Balance	[5]		1
Change in unrealized gain (losses) still held	[2],[5]		1
Available-for-sale securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Transfers into Level 3			23
Transfers out of level 3		(2)
Available-for-sale securities | Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		123	166
Gains (losses) in OCI	[6]	(1)
Sales		(7)	(4)
Issuances		0	0
Settlements		(38)	(39)
Ending Balance		77	123
Available-for-sale securities | Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		187	169
Gains (losses) in OCI	[6]	1
Purchases		63	102
Sales		(12)	(62)
Issuances		0	0
Settlements		(15)	(22)
Ending Balance		224	187
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		174	155
Gains (losses) in Earnings	[1]	(1)	(2)
Gains (losses) in OCI	[6]	43
Purchases		10	67
Sales		(19)	(3)
Issuances		0	0
Settlements		(33)	(43)
Ending Balance		174	174
Change in unrealized gain (losses) still held	[2]		(4)
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		108	85
Gains (losses) in Earnings	[1]	1	2
Gains (losses) in OCI	[6]	(1)	(5)
Transfers into Level 3			23
Transfers out of level 3		(2)
Purchases		10	41
Issuances		0	0
Settlements		(6)	(38)
Ending Balance		¥ 110	¥ 108
[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, 2016 and 2017.
[3]	Gains (losses) in Earnings are reported in Other noninterest income (expenses).
[4]	Gains (losses) in Earnings are reported in Trading account gains (losses)-net, Foreign exchange gains (losses)-net or Other noninterest income (expenses).
[5]	Total Level 3 derivative exposures have been netted on the table for presentation purposes only.
[6]	Gains (losses) in OCI are reported in Other comprehensive income (loss).

Fair Value (Quantitative Inform

Fair Value (Quantitative Information About Level Three Fair Value Measurements) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Available For Sale And Trading Securities | Residential mortgage-backed securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value		¥ 92	¥ 144
Principal valuation technique		Discounted cash flow Price-based
Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment rate	[1]	7.00%	7.00%
Default rate	[1]	0.00%	0.00%
Recovery rate	[1]	100.00%	100.00%
Discount margin	[1]	0.55%	0.60%
Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment rate		0.00%	3.00%
Default rate		0.00%	0.00%
Recovery rate		100.00%	100.00%
Discount margin		0.15%	0.13%
Available For Sale And Trading Securities | Residential mortgage-backed securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment rate		18.00%	19.00%
Default rate		1.00%	2.00%
Recovery rate		100.00%	100.00%
Discount margin		1.70%	1.80%
Available For Sale And Trading Securities | Commercial mortgage-backed securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value		¥ 224	¥ 189
Principal valuation technique		Discounted cash flow Price-based
Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount margin	[1]	0.28%	0.37%
Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount margin		0.04%	0.06%
Available For Sale And Trading Securities | Commercial mortgage-backed securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount margin		2.05%	5.80%
Available For Sale And Trading Securities | Corporate bonds and other debt securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value		¥ 1,336	¥ 1,002
Principal valuation technique		Discounted cash flow Price-based
Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment rate	[1],[2]	29.00%	19.00%
Default rate	[1],[2]	2.00%	2.00%
Recovery rate	[1],[2]	68.00%	68.00%
Discount margin	[1],[2]	1.31%	1.51%
Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment rate	[2]	16.00%	0.00%
Default rate	[2]	1.00%	0.00%
Recovery rate	[2]	60.00%	60.00%
Discount margin	[2]	0.08%	0.11%
Available For Sale And Trading Securities | Corporate bonds and other debt securities | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment rate	[2]	30.00%	21.00%
Default rate	[2]	2.00%	2.00%
Recovery rate	[2]	68.00%	69.00%
Discount margin	[2]	11.81%	11.15%
Available For Sale And Trading Securities | Japanese corporate bonds and foreign corporate bonds | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount margin	[1],[3]	3.59%	4.54%
Available For Sale And Trading Securities | Japanese corporate bonds and foreign corporate bonds | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount margin	[3]	0.10%	0.10%
Available For Sale And Trading Securities | Japanese corporate bonds and foreign corporate bonds | Discounted Cash Flow Method Or Transaction Price Valuation Technique | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount margin	[3]	9.39%	38.50%
Derivative contracts | Interest rate contracts
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value		¥ 26	¥ 26
Principal valuation technique	[4]	Internal valuation model
Derivative contracts | Interest rate contracts | Internal Valuation Model | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
IR - IR correlation		23.00%	32.00%
Default rate	[5]	0.00%	0.00%
Derivative contracts | Interest rate contracts | Internal Valuation Model | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
IR - IR correlation		100.00%	100.00%
Default rate	[5]	63.00%	63.00%
Derivative contracts | Foreign exchange contracts
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value		¥ 8	¥ 7
Principal valuation technique	[4]	Internal valuation model
Derivative contracts | Foreign exchange contracts | Internal Valuation Model | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
FX - IR correlation		5.00%	5.00%
FX - FX correlation		55.00%	54.00%
Default rate	[5]	0.00%	0.00%
Derivative contracts | Foreign exchange contracts | Internal Valuation Model | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
FX - IR correlation		52.00%	50.00%
FX - FX correlation		55.00%	54.00%
Default rate	[5]	63.00%	63.00%
Derivative contracts | Equity-related contracts
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value		¥ (25)	¥ 5
Principal valuation technique	[4]	Internal valuation model
Derivative contracts | Equity-related contracts | Internal Valuation Model | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Equity - IR correlation		25.00%	30.00%
Equity - FX correlation		55.00%	55.00%
Equity volatility		6.00%	10.00%
Derivative contracts | Equity-related contracts | Internal Valuation Model | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Equity - IR correlation		25.00%	30.00%
Equity - FX correlation		55.00%	55.00%
Equity volatility		59.00%	40.00%
Derivative contracts | Credit-related contracts
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value			¥ (1)
Principal valuation technique	[4]	Internal valuation model
Derivative contracts | Credit-related contracts | Internal Valuation Model | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Default rate		0.00%	0.00%
Credit correlation		30.00%	29.00%
Derivative contracts | Credit-related contracts | Internal Valuation Model | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Default rate		5.00%	42.00%
Credit correlation		100.00%	100.00%
Long-term debt
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value		¥ 593	¥ 623
Principal valuation technique	[4]	Internal valuation model
Long-term debt | Internal Valuation Model | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
IR - IR correlation		23.00%	32.00%
FX - IR correlation		5.00%	5.00%
FX - FX correlation		55.00%	54.00%
Default rate		0.00%	0.00%
Equity - IR correlation		25.00%	30.00%
Credit correlation		33.00%	28.00%
Equity - FX correlation		55.00%	55.00%
Equity volatility		5.00%	14.00%
Equity correlation		20.00%	18.00%
Long-term debt | Internal Valuation Model | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
IR - IR correlation		100.00%	100.00%
FX - IR correlation		52.00%	50.00%
FX - FX correlation		55.00%	54.00%
Default rate		3.00%	5.00%
Equity - IR correlation		25.00%	30.00%
Credit correlation		100.00%	100.00%
Equity - FX correlation		55.00%	55.00%
Equity volatility		40.00%	39.00%
Equity correlation		100.00%	100.00%
[1]	Weighted averages are calculated by weighting each input by the relative fair value of the respective financial instruments.
[2]	These inputs are mainly used for determining the fair values of securitization products such as CDO, CLO and ABS, other than RMBS and CMBS.
[3]	This input is mainly used for determining the fair values of Japanese corporate bonds and foreign corporate bonds.
[4]	Internal valuation model includes discounted cash flow models and the Black-Scholes option pricing model.
[5]	This input represents the counterparty default rate derived from the MHFG Group's own internal credit analyses.

Fair Value (Fair Value Hierarch

Fair Value (Fair Value Hierarchy for Assets and Liabilities Measured on Nonrecurring Basis) (Detail) - Fair Value, Measurements, Nonrecurring - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
Assets:
Loans	¥ 124	¥ 124
Loans held-for-sale	7	13
Other investments	7	1
Premises and equipment-net	7
Total assets measured at fair value	145	138
Aggregate cost
Assets:
Loans	194	197
Loans held-for-sale	8	14
Other investments	11	2
Premises and equipment-net	11	1
Goodwill		6
Total assets measured at fair value	224	220
Level 1
Assets:
Other investments	6
Total assets measured at fair value	6
Level 2
Assets:
Loans held-for-sale	7	7
Premises and equipment-net	6
Total assets measured at fair value	13	7
Level 3
Assets:
Loans	124	124
Loans held-for-sale		6
Other investments	1	1
Premises and equipment-net	1
Total assets measured at fair value	¥ 126	¥ 131

Fair Value (Carrying Amounts an

Fair Value (Carrying Amounts and Fair Values of Certain Financial Instruments Excluding Financial Instruments Which Are Carried at Fair Value on a Recurring Basis and Those Outside Scope of Asc 825) (Detail) - JPY (¥) ¥ in Millions		Mar. 31, 2017	Mar. 31, 2016
Financial liabilities:
Long-term debt		¥ 1,496,488	¥ 1,055,626
Carrying amount
Financial assets:
Cash and due from banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		60,943,000	48,757,000
Investments		3,817,000	4,819,000
Loans, net of allowance for loan losses	[1]	81,662,000	77,040,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		42,205,000	39,908,000
Interest-bearing deposits		110,125,000	100,228,000
Due to trust accounts		4,123,000	4,467,000
Other short-term borrowings		1,477,000	2,080,000
Long-term debt		13,009,000	13,691,000
Estimated fair value
Financial assets:
Cash and due from banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		60,943,000	48,757,000
Investments		3,846,000	4,873,000
Loans, net of allowance for loan losses	[1]	82,696,000	78,241,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		42,205,000	39,908,000
Interest-bearing deposits		110,124,000	100,234,000
Due to trust accounts		4,123,000	4,467,000
Other short-term borrowings		1,477,000	2,080,000
Long-term debt		13,078,000	13,863,000
Estimated fair value | Level 1
Financial assets:
Cash and due from banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		1,063,000	923,000
Investments		3,846,000	4,873,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		20,544,000	17,223,000
Interest-bearing deposits		56,738,000	46,207,000
Estimated fair value | Level 2
Financial assets:
Cash and due from banks, call loans and funds sold, and receivables under resale agreements and securities borrowing transactions		59,880,000	47,834,000
Financial liabilities:
Noninterest-bearing deposits, call money and funds purchased, and payables under repurchase agreements and securities lending transactions		21,661,000	22,685,000
Interest-bearing deposits		53,386,000	54,027,000
Due to trust accounts		4,123,000	4,467,000
Other short-term borrowings		1,477,000	2,080,000
Long-term debt		12,120,000	12,969,000
Estimated fair value | Level 3
Financial assets:
Loans, net of allowance for loan losses	[1]	82,696,000	78,241,000
Financial liabilities:
Long-term debt		¥ 958,000	¥ 894,000
[1]	Loans, net of allowance for loan losses include items measured at fair value on a nonrecurring basis.

Offsetting of Financial Asse185

Offsetting of Financial Assets and Financial Liabilities (Information of Offsetting of Financial Assets and Financial Liabilities) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2017	Mar. 31, 2016
Offsetting Financial Assets And Financial Liabilities [Line Items]
Derivative assets, Gross amounts recognized	[1]	¥ 10,608	¥ 14,130
Derivative assets, Gross amounts offset on the balance sheet	[1]	0	0
Derivative assets, Net amounts presented on the balance sheet	[1],[2]	10,608	14,130
Derivative assets, Amounts not offset on the balance sheet, Financial instruments	[1],[3],[4]	(8,966)	(12,167)
Derivative assets, Amounts not offset on the balance sheet, Cash collateral	[1],[3]	(620)	(599)
Derivative assets, Net amounts	[1]	1,022	1,364
Receivables under resale agreements, Gross amounts recognized	[1]	8,698	7,490
Receivables under resale agreements, Gross amounts offset on the balance sheet	[1]	0	0
Receivables under resale agreements, Net amounts presented on the balance sheet	[1],[2]	8,698	7,490
Receivables under resale agreements, Amounts not offset on the balance sheet, Financial instruments	[1],[3],[4]	(8,662)	(7,461)
Receivables under resale agreements, Amounts not offset on the balance sheet, Cash collateral	[1],[3]	0	0
Receivables under resale agreements, Net amounts	[1]	36	29
Receivables under securities borrowing transactions, Gross amounts recognized	[1]	3,127	3,327
Receivables under securities borrowing transactions, Gross amounts offset on the balance sheet	[1]	0	0
Receivables under securities borrowing transactions, Net amounts presented on the balance sheet	[1],[2]	3,127	3,327
Receivables under securities borrowing transactions, Amounts not offset on the balance sheet, Financial instruments	[1],[3],[4]	(3,116)	(3,318)
Receivables under securities borrowing transactions, Amounts not offset on the balance sheet, Cash collateral	[1],[3]	0	0
Receivables under securities borrowing transactions, Net amounts	[1]	11	9
Financial assets, Gross amounts recognized, Total	[1]	22,433	24,947
Financial assets, Gross amounts offset on the balance sheet, Total	[1]	0	0
Financial assets, Net amounts presented on the balance sheet, Total	[1],[2]	22,433	24,947
Financial assets, Amounts not offset on the balance sheet, Financial instruments, Total	[1],[3],[4]	(20,744)	(22,946)
Financial assets, Amounts not offset on the balance sheet, Cash collateral, Total	[1],[3]	(620)	(599)
Financial assets, Net amounts, Total	[1]	1,069	1,402
Derivative liabilities, Gross amounts recognized	[1]	10,405	13,652
Derivative liabilities, Gross amounts offset on the balance sheet	[1]	0	0
Derivative liabilities, Net amounts presented on the balance sheet	[1],[2]	10,405	13,652
Derivative liabilities, Amounts not offset on the balance sheet, Financial instruments	[1],[3],[4]	(8,866)	(12,043)
Derivative liabilities, Amounts not offset on the balance sheet, Cash collateral	[1],[3]	(901)	(748)
Derivative liabilities, Net amounts	[1]	638	861
Payables under repurchase agreements, Gross amounts recognized	[1]	17,446	16,507
Payables under repurchase agreements, Gross amounts offset on the balance sheet	[1]	0	0
Payables under repurchase agreements, Net amounts presented on the balance sheet	[1],[2]	17,446	16,507
Payables under repurchase agreements, Amounts not offset on the balance sheet, Financial instruments	[1],[3],[4]	(17,391)	(16,464)
Payables under repurchase agreements, Amounts not offset on the balance sheet, Cash collateral	[1],[3]	0	0
Payables under repurchase agreements, Net amounts	[1]	55	43
Payables under securities lending transactions, Gross amounts recognized	[1]	1,458	2,538
Payables under securities lending transactions, Gross amounts offset on the balance sheet	[1]	0	0
Payables under securities lending transactions, Net amounts presented on the balance sheet	[1],[2]	1,458	2,538
Payables under securities lending transactions, Amounts not offset on the balance sheet, Financial instruments	[1],[3],[4]	(1,455)	(2,531)
Payables under securities lending transactions, Amounts not offset on the balance sheet, Cash collateral	[1],[3]	0	0
Payables under securities lending transactions, Net amounts	[1]	3	7
Financial liabilities, Gross amounts recognized, Total	[1]	29,309	32,697
Financial liabilities, Gross amounts offset on the balance sheet, Total	[1]	0	0
Financial liabilities, Net amounts presented on the balance sheet, Total	[1],[2]	29,309	32,697
Financial liabilities, Amounts not offset on the balance sheet, Financial instruments, Total	[1],[3],[4]	(27,712)	(31,038)
Financial liabilities, Amounts not offset on the balance sheet, Cash collateral, Total	[1],[3]	(901)	(748)
Financial liabilities, Net amounts, Total	[1]	¥ 696	¥ 911
[1]	Amounts relating to master netting arrangements or similar agreements where the MHFG Group does not have the legal right of set-off or where uncertainty exists as to the enforceability of these agreements are excluded. For derivatives, the table includes amounts relating to over-the-counter ("OTC") and OTC-cleared derivatives that are subject to enforceable master netting arrangements or similar agreements.
[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 Se186

Repurchase Agreements and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Amounts of Liabilities Associated with Repurchase Agreements and Securities Lending Transactions by Remaining Contractual Maturity) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2017	Mar. 31, 2016
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	[1]	¥ 17,970	¥ 16,833
Securities lending transactions	[1]	1,919	2,845
Total		19,889	19,678
Overnight and continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		249	6,289
Securities lending transactions		320	1,909
Total		569	8,198
Up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		12,700	6,125
Securities lending transactions		1,359	700
Total		14,059	6,825
31 to 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		3,897	3,582
Total		3,897	3,582
Greater than 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		1,124	837
Securities lending transactions		240	236
Total		¥ 1,364	¥ 1,073
[1]	Amounts exceeded the gross amounts recognized in Note 29 "Offsetting of financial assets and financial liabilities" by ¥633 billion and ¥985 billion, at March 31, 2016 and 2017, 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 Se187

Repurchase Agreements and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Amounts of Liabilities Associated with Repurchase Agreements and Securities Lending Transactions by Class of Underlying Collateral) (Detail) - JPY (¥) ¥ in Billions		Mar. 31, 2017	Mar. 31, 2016
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements	[1]	¥ 17,970	¥ 16,833
Securities lending transactions	[1]	1,919	2,845
Japanese government bonds and Japanese local government bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		1,127	532
Securities lending transactions		1,152	1,891
Foreign government bonds and foreign agency mortgage-backed securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		15,782	15,781
Securities lending transactions		375	700
Commercial Paper and Corporate Bonds
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		294	221
Securities lending transactions		47	27
Equity Securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		578	141
Securities lending transactions		320	185
Other securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Repurchase agreements		189	158
Securities lending transactions		¥ 25	¥ 42
[1]	Amounts exceeded the gross amounts recognized in Note 29 "Offsetting of financial assets and financial liabilities" by ¥633 billion and ¥985 billion, at March 31, 2016 and 2017, 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 Se188

Repurchase Agreements and Securities Lending Transactions Accounted for as Secured Borrowings (Gross Amounts of Liabilities Associated with Repurchase Agreements and Securities Lending Transactions by Class of Underlying Collateral) (Parenthetical) (Detail) - JPY (¥) ¥ in Billions	Mar. 31, 2017	Mar. 31, 2016
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	¥ 985	¥ 633

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - Loans	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Related Party Transaction [Line Items]
Number of loans impaired	0	0

Business Segment Information (I

Business Segment Information (Information for Reportable Segments) (Detail) - JPY (¥) ¥ in Billions		12 Months Ended
		Mar. 31, 2017		Mar. 31, 2016		Mar. 31, 2015	[3]
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]	¥ 867.8	[2]	¥ 1,003.7		¥ 1,129.4
Net noninterest income	[1]	1,224.9	[2]	1,217.9		1,118.3
Gross profits	[1]	2,092.7	[2]	2,221.6	[4]	2,247.7
General and administrative expenses	[1]	1,420.5	[2]	1,345	[4]	1,321.2
Others	[1]	(8.8)	[2]	(23.7)	[4]	(49.6)
Net business profits	[1],[5]	663.4	[2]	852.9	[4]	876.9
Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]	836.5	[2]	959.4		1,087.3
Net noninterest income	[1]	686.7	[2]	675.3		598.4
Gross profits	[1]	1,523.2	[2]	1,634.7		1,685.7
General and administrative expenses	[1]	982.7	[2]	903.3		904.7
Others	[1]	(8.7)	[2]	(22.1)		(43.2)
Net business profits	[1],[5]	531.8	[2]	709.3		737.8
Mizuho Bank, Limited Non-consolidated | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]	719.8	[2]	830.1		934.9
Net noninterest income	[1]	600.6	[2]	633.7		560.6
Gross profits	[1]	1,320.4	[2]	1,463.8		1,495.5
General and administrative expenses	[1]	866.6	[2]	833.3		833.7
Net business profits	[1],[5]	453.8	[2]	630.5		661.8
Others
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]	2.6	[2]	2.8		0.9
Net noninterest income	[1]	83.3	[2]	68.1		61.5
Gross profits	[1]	85.9	[2]	70.9		62.4
General and administrative expenses	[1]	78.7	[2]	63.3		54
Others	[1]	5	[2]	2.5		(2.7)
Net business profits	[1],[5]	12.2	[2]	10.1		5.7
Others | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]	116.7	[2]	129.3		152.4
Net noninterest income	[1]	86.1	[2]	41.6		37.8
Gross profits	[1]	202.8	[2]	170.9		190.2
General and administrative expenses	[1]	116.1	[2]	70		71
Others	[1]	(8.7)	[2]	(22.1)		(43.2)
Net business profits	[1],[5]	78	[2]	78.8		76
MizuhoTrust Banking Company Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]	30.2	[2]	36.1		39.4
Net noninterest income	[1]	121.8	[2]	130.7		122.6
Gross profits	[1]	152	[2]	166.8		162
General and administrative expenses	[1]	101.6	[2]	99.1		94.5
Others	[1]	(5.2)	[2]	(4.2)		(3.7)
Net business profits	[1],[5]	45.2	[2]	63.5		63.8
Mizuho Securities Company Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]	(1.5)	[2]	5.4		1.8
Net noninterest income	[1]	333.1	[2]	343.8		335.8
Gross profits	[1]	331.6	[2]	349.2		337.6
General and administrative expenses	[1]	257.5	[2]	279.3		268
Others	[1],[2]	0.1
Net business profits	[1],[5]	74.2	[2]	69.9		69.6
Personal Banking | Mizuho Bank, Limited Non-consolidated | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]			214.8		213.4
Net noninterest income	[1]			45		48.7
Gross profits	[1]			259.8		262.1
General and administrative expenses	[1]			234.4		233.5
Net business profits	[1],[5]			25.4		28.6
Retail banking | Mizuho Bank, Limited Non-consolidated | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]			75.7		77.6
Net noninterest income	[1]			53.1		53.7
Gross profits	[1]			128.8		131.3
General and administrative expenses	[1]			118.6		118.4
Net business profits	[1],[5]			10.2		12.9
Corporate Banking (Large Corporations) | Mizuho Bank, Limited Non-consolidated | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]			173		179.5
Net noninterest income	[1]			143.7		128
Gross profits	[1]			316.7		307.5
General and administrative expenses	[1]			91.9		94.4
Net business profits	[1],[5]			224.8		213.1
Corporate Banking | Mizuho Bank, Limited Non-consolidated | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]			97.5		99.6
Net noninterest income	[1]			77.5		79.8
Gross profits	[1]			175		179.4
General and administrative expenses	[1]			75.2		76.5
Net business profits	[1],[5]			99.8		102.9
Financial Institutions & Public Sector Business | Mizuho Bank, Limited Non-consolidated | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]			32.5		33.3
Net noninterest income	[1]			31.8		27.4
Gross profits	[1]			64.3		60.7
General and administrative expenses	[1]			29.8		30.3
Net business profits	[1],[5]			34.5		30.4
International Banking | Mizuho Bank, Limited Non-consolidated | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]			175.5		147.1
Net noninterest income	[1]			185.1		164.9
Gross profits	[1]			360.6		312
General and administrative expenses	[1]			122.1		92.6
Net business profits	[1],[5]			238.5		219.4
Trading and others | Mizuho Bank, Limited Non-consolidated | Mizuho Bank, Limited Consolidated
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Net interest income	[1]			61.1		184.4
Net noninterest income	[1]			97.5		58.1
Gross profits	[1]			158.6		242.5
General and administrative expenses	[1]			161.3		188
Net business profits	[1],[5]			(2.7)		¥ 54.5
Operating Segments [Member] | Retail And Business Banking Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits		646.1		676.4	[4]
General and administrative expenses		678.3		661.2	[4]
Net business profits	[5]	(32.2)		15.2	[4]
Operating Segments [Member] | Corporate And Institutional Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits		445.1		434.9	[4]
General and administrative expenses		186.7		183.2	[4]
Net business profits	[5]	258.4		251.7	[4]
Operating Segments [Member] | Global Corporate Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits		386.5		403.8	[4]
General and administrative expenses		237.8		232.7	[4]
Net business profits	[5]	148.7		171.1	[4]
Operating Segments [Member] | Global Markets Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits		539.4		577.7	[4]
General and administrative expenses		200.9		178.9	[4]
Net business profits	[5]	338.5		398.8	[4]
Operating Segments [Member] | Asset Management Company
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits		49.6		52.1	[4]
General and administrative expenses		29.3		30.1	[4]
Net business profits	[5]	20.3		22	[4]
Others
Japan Gaap Schedule of Segment Reporting Information, by Segment [Line Items]
Gross profits	[6]	26		76.7	[4]
General and administrative expenses	[6]	87.5		58.9	[4]
Others	[6]	(8.8)		(23.7)	[4]
Net business profits	[5],[6]	¥ (70.3)		¥ (5.9)	[4]
[1]	"Others (h)" and "Others (k)" include the elimination of transactions between consolidated subsidiaries.
[2]	Segment information based on the relevant principal consolidated subsidiaries for the fiscal year ended March 31, 2017 is presented for comparability purposes. Due to system limitations, it is impracticable to present the details of MHBK (Non-consolidated).
[3]	Beginning on April 1, 2015, new allocation methods have been applied to the calculation of "Gross profits" and "General and administrative expenses" for reportable segments of MHBK. Figures for the fiscal year ended March 31, 2015 have been restated for the new allocation methods.
[4]	Following the introduction of an in-house company system based on customer segments in April 2016, segment information for the fiscal year ended March 31, 2016 was restated to reflect the relevant changes as transaction data on a customer segment basis had been maintained. Due to such data not being available, it is impracticable to restate segment information for the fiscal year ended March 31, 2015.
[5]	Net business profits is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (or the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income) less general and administrative expenses. Measurement of net business profits is required for regulatory reporting to the Financial Services Agency.
[6]	"Others" includes items which should be eliminated as internal transactions between each segment on a consolidated basis.

Business Segment Information (R

Business Segment Information (Reconciliation of Total Net Business Profits Under Internal Management Reporting System to Income Loss Before Income Tax Expense Benefit Shown on Consolidated Statements of Income) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017		Mar. 31, 2016		Mar. 31, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net business profits	[1],[2]	¥ 663,400	[3]	¥ 852,900	[4]	¥ 876,900	[5]
U.S. GAAP adjustments		(387,800)		201,300		230,800
(Provision) credit for loan losses		(37,668)		(34,560)		60,223
Net gains (losses) related to equity investments		259,600		188,400		160,100
Non-recurring personnel expense		(8,800)		(3,900)		(8,000)
Gains on disposal of premises and equipment		5,638		10,223		2,754
(Provision) credit for losses on off-balance-sheet instruments		(19,464)		16,447		2,827
Others-net		5,600		(34,000)		(57,900)
Income before income tax expense		¥ 480,375		¥ 1,196,605		¥ 1,267,653
[1]	"Others (h)" and "Others (k)" include the elimination of transactions between consolidated subsidiaries.
[2]	Net business profits is used in Japan as a measure of the profitability of core banking operations, and is defined as gross profits (or the sum of net interest income, fiduciary income, net fee and commission income, net trading income and net other operating income) less general and administrative expenses. Measurement of net business profits is required for regulatory reporting to the Financial Services Agency.
[3]	Segment information based on the relevant principal consolidated subsidiaries for the fiscal year ended March 31, 2017 is presented for comparability purposes. Due to system limitations, it is impracticable to present the details of MHBK (Non-consolidated).
[4]	Following the introduction of an in-house company system based on customer segments in April 2016, segment information for the fiscal year ended March 31, 2016 was restated to reflect the relevant changes as transaction data on a customer segment basis had been maintained. Due to such data not being available, it is impracticable to restate segment information for the fiscal year ended March 31, 2015.
[5]	Beginning on April 1, 2015, new allocation methods have been applied to the calculation of "Gross profits" and "General and administrative expenses" for reportable segments of MHBK. Figures for the fiscal year ended March 31, 2015 have been restated for the new allocation methods.

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, 2017	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Total revenue	[1]	¥ 2,877,100	¥ 3,384,100	¥ 3,258,900
Total expenses	[2]	2,396,700	2,187,500	1,991,200
Income before income tax expense		480,375	1,196,605	1,267,653
Net income		389,131	850,063	830,233
Total assets at end of fiscal year		200,456,304	193,810,151	190,114,400
Japan
Segment Reporting Information [Line Items]
Total revenue	[1]	1,748,300	2,288,500	2,396,900
Total expenses	[2]	1,712,300	1,534,200	1,459,900
Income before income tax expense		36,000	754,300	937,000
Net income		5,700	464,700	565,600
Total assets at end of fiscal year		138,832,300	133,157,100	127,468,200
United States of America
Segment Reporting Information [Line Items]
Total revenue	[1]	500,300	434,400	324,100
Total expenses	[2]	303,200	282,600	210,800
Income before income tax expense		197,100	151,800	113,300
Net income		167,600	136,900	79,700
Total assets at end of fiscal year		30,262,000	28,985,300	31,074,900
Others
Segment Reporting Information [Line Items]
Total revenue	[1]	70,300	45,700	102,400
Total expenses	[2]	29,100	28,700	24,300
Income before income tax expense		41,200	17,000	78,100
Net income		38,800	15,400	76,200
Total assets at end of fiscal year		4,203,300	4,227,500	4,871,000
Europe
Segment Reporting Information [Line Items]
Total revenue	[1]	190,700	187,500	211,800
Total expenses	[2]	136,200	126,200	133,800
Income before income tax expense		54,500	61,300	78,000
Net income		39,500	51,100	74,300
Total assets at end of fiscal year		10,629,100	11,616,900	10,880,600
Asia/Oceania excluding Japan, and others
Segment Reporting Information [Line Items]
Total revenue	[1]	367,500	428,000	223,700
Total expenses	[2]	215,900	215,800	162,400
Income before income tax expense		151,600	212,200	61,300
Net income		137,500	182,000	34,400
Total assets at end of fiscal year		¥ 16,529,600	¥ 15,823,400	¥ 15,819,700
[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.193

Mizuho Financial Group, Inc., Parent Company (Condensed Balance Sheets Parent Company Only) (Detail) - JPY (¥) ¥ in Millions	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Assets:
Cash and due from banks	¥ 1,592,191	¥ 1,322,597	¥ 1,528,306	¥ 1,696,879
Interest-bearing deposits in other banks	45,994,780	35,327,408
Other	4,992,329	4,696,890
Total	200,456,304	193,810,151	190,114,400
Liabilities and shareholders' equity:
Long-term debt	14,529,414	14,765,527
Other liabilities	5,026,525	6,476,723
Shareholders' equity	8,261,357	8,014,551
Total	200,456,304	193,810,151
Parent Company
Assets:
Cash and due from banks	15,912	137	¥ 223	¥ 167
Interest-bearing deposits in other banks	4,278	16,305
Investments in subsidiaries and affiliated companies	8,993,388	8,840,003
Long-term loans receivable from subsidiaries	2,697,250	624,518
Other	477,375	400,590
Total	12,188,203	9,881,553
Liabilities and shareholders' equity:
Short-term borrowings	1,156,100	1,186,345
Long-term debt	2,632,250	584,518
Other liabilities	138,496	96,139
Shareholders' equity	8,261,357	8,014,551
Total	¥ 12,188,203	¥ 9,881,553

Mizuho Financial Group, Inc.194

Mizuho Financial Group, Inc., Parent Company (Condensed Statements of Income Parent Company Only) (Detail) - JPY (¥) ¥ in Millions		12 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Income:
Total	[1]	¥ 2,877,100	¥ 3,384,100	¥ 3,258,900
Expenses:
Interest expense		601,712	495,407	411,982
Equity in undistributed net income of subsidiaries		26,785	28,969	17,502
Income tax expense		91,244	346,542	437,420
Net income attributable to MHFG shareholders		362,440	850,492	803,048
Parent Company
Income:
Management fees from subsidiaries		48,594	39,267	32,163
Interest Income on Loans and Discounts		39,359	9,630	799
Other income		21,054	1,855	37,308
Total		437,155	343,636	414,938
Expenses:
Operating expenses		38,927	31,063	26,855
Interest expense		38,759	11,914	8,937
Bond issuance cost		9,835	3,230	865
Other expense		7,708	5,973	1,828
Total		95,229	52,180	38,485
Equity in undistributed net income of subsidiaries		21,251	559,553	427,037
Income before income tax expense		363,177	851,009	803,490
Income tax expense		737	517	442
Net income attributable to MHFG shareholders		362,440	850,492	803,048
Parent Company | Banking Subsidiary
Income:
Dividends from subsidiaries and affiliated companies		300,530	272,070	316,035
Parent Company | Non Banking Subsidiaries And Affiliated Companies
Income:
Dividends from subsidiaries and affiliated companies		¥ 27,618	¥ 20,814	¥ 28,633
[1]	Total revenue is comprised of Interest and dividend income and Noninterest income.

Mizuho Financial Group, Inc.195

Mizuho Financial Group, Inc., Parent Company (Condensed Statements of Cash Flows Parent Company Only) (Detail) - JPY (¥) ¥ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	¥ 362,440	¥ 850,492	¥ 803,048
Net cash provided by operating activities	1,213,308	241,710	1,205,926
Cash flows from investing activities:
Net change in loans	(5,606,627)	(1,923,627)	(2,800,196)
Purchases of premises and equipment	(430,913)	(388,565)	(419,912)
Net cash used in investing activities	(12,801,572)	(5,978,075)	(5,673,888)
Cash flows from financing activities:
Net change in short-term borrowings	(589,512)	571,901	(4,480,378)
Proceeds from issuance of long-term debt	4,496,041	2,723,168	6,537,703
Repayment of long-term debt	(4,734,010)	(2,307,082)	(2,196,492)
Proceeds from issuance of common stock	6	5	6
Purchases of treasury stock	(1,435)	(13)	(12)
Dividends paid	(190,031)	(195,283)	(176,186)
Net cash provided by financing activities	11,869,753	5,558,717	4,264,631
Effect of exchange rate changes on cash and due from banks	(11,895)	(28,061)	34,758
Net increase (decrease) in cash and due from banks	269,594	(205,709)	(168,573)
Cash and due from banks at beginning of fiscal year	1,322,597	1,528,306	1,696,879
Cash and due from banks at end of fiscal year	1,592,191	1,322,597	1,528,306
Parent Company
Cash flows from operating activities:
Net income	362,440	850,492	803,048
Adjustments and other	(40,595)	(546,946)	(460,230)
Net cash provided by operating activities	321,845	303,546	342,818
Cash flows from investing activities:
Net change in loans	(2,022,860)	(479,948)	(150,000)
Purchases of premises and equipment	(40,362)	(165)	(159,670)
Payments for purchases of securities of subsidiaries	(65,269)	(2,249)
Proceeds from withdrawal of securities of subsidiaries	13,359
Net change in other investing activities	6,691	1,872	3,294
Net cash used in investing activities	(2,108,441)	(480,490)	(306,376)
Cash flows from financing activities:
Net change in short-term borrowings	(30,000)	(10,000)	130,000
Proceeds from issuance of long-term debt	2,022,860	479,948	150,000
Repayment of long-term debt		(98,800)	(141,200)
Proceeds from issuance of common stock	6	5	6
Purchases of treasury stock	(1,435)	(13)	(12)
Dividends paid	(190,031)	(195,283)	(176,186)
Net change in other financing activities	971	1,001	1,006
Net cash provided by financing activities	1,802,371	176,858	(36,386)
Effect of exchange rate changes on cash and due from banks	0	0	0
Net increase (decrease) in cash and due from banks	15,775	(86)	56
Cash and due from banks at beginning of fiscal year	137	223	167
Cash and due from banks at end of fiscal year	¥ 15,912	¥ 137	¥ 223