Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority noncontrolling interest income (loss), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, increase (decrease) in enacted tax rate, prior year income taxes, increase (decrease) in deferred tax asset valuation allowance, and other adjustments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

Name:	us-gaap_IncomeTaxReconciliationOtherReconcilingItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Income Taxes (Reconciliation of Income Tax Expense at Effective Statutory Tax Rate to Actual Income Tax Expense) (Parenthetical) (Detail) - JPY (¥) ¥ in Millions		3 Months Ended	12 Months Ended
	Dec. 22, 2017	Mar. 31, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Reconciliation Of Income Tax Expense Benefit And Statutory Federal Tax Rate [Line Items]
Effective statutory tax rate	35.00%	21.00%	30.62%	30.62%	30.86%
Reclassification Of Undistributed Earnings In Subsidiaries To Others [Member]
Reconciliation Of Income Tax Expense Benefit And Statutory Federal Tax Rate [Line Items]
Change in undistributed earnings of subsidaries reclassified to others				¥ (21,347)	¥ (1,972)