For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6503844

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

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Amount included in accumulated other comprehensive income (AOCI) related to transition obligation (asset) expected to be recognized as components of net periodic benefit cost (credit) for the fiscal year that follows the most recent annual statement of financial position.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (s)

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Amount included in accumulated other comprehensive income (AOCI) related to gain (loss) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

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Amount included in accumulated other comprehensive income (AOCI) related to prior service cost (credit) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

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- Definition

If aggregate disclosures are presented, the aggregate pension accumulated benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 55

-Paragraph 17

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-Section 50

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If aggregate disclosures are presented, the aggregate fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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If aggregate disclosures are presented, the aggregate projected benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented.

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Amount of employer's best estimate of contributions expected to be paid to the plan in the current remaining fiscal period.

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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

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The amount of the cost recognized during the period for defined contribution plans.

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-Name Accounting Standards Codification

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Pension Plans - Additional Information (Detail) (JPY ¥) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Domestic Pension Plans Of Foreign Entity Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Estimated portions of net prior service credit that will be recognized as a component of net pension cost		¥ (924)
Estimated portions of net actuarial loss that will be recognized as a component of net pension cost		547
Estimated portions of net transition obligation that will be recognized as a component of net pension		53
Accumulated benefit obligations for all defined benefit pension plans	71,863	71,863	56,864
Aggregate projected benefit obligations for plans with accumulated benefit obligations in excess of plan assets	19,924	19,924	4,006
Aggregate accumulated benefit obligations for plans with accumulated benefit obligations in excess of plan assets	17,487	17,487	3,738
Aggregate fair values of plan assets for the plans with accumulated benefit obligations in excess of plan assets	7,015	7,015	1,034
Expected pension plans contributions by Company and certain subsidiaries		2,976
Cost recognized for defined contribution pension plans of Company and certain of its subsidiaries		1,023	926	816
Overseas Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Estimated portions of net prior service credit that will be recognized as a component of net pension cost	(3)
Estimated portions of net actuarial loss that will be recognized as a component of net pension cost	60
Estimated portions of net transition obligation that will be recognized as a component of net pension	3
Accumulated benefit obligations for all defined benefit pension plans	61,730	61,730	5,128
Aggregate projected benefit obligations for plans with accumulated benefit obligations in excess of plan assets	5,555	5,555	5,335
Aggregate accumulated benefit obligations for plans with accumulated benefit obligations in excess of plan assets	5,372	5,372	5,016
Aggregate fair values of plan assets for the plans with accumulated benefit obligations in excess of plan assets	4,096	4,096	3,799
Expected pension plans contributions by Company and certain subsidiaries		11,191
Cost recognized for defined contribution pension plans of Company and certain of its subsidiaries		¥ 1,560	¥ 574	¥ 593
Equity securities \| Domestic Pension Plans Of Foreign Entity Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Portfolio of plans	30.00%	30.00%	30.00%
Equity securities \| Overseas Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Portfolio of plans	40.00%	40.00%
Debt Securities \| Domestic Pension Plans Of Foreign Entity Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Portfolio of plans	40.00%	40.00%	40.00%
Debt Securities \| Overseas Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Portfolio of plans	60.00%	60.00%	90.00%
Other investment \| Domestic Pension Plans Of Foreign Entity Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Portfolio of plans	30.00%	30.00%	30.00%
Other investment \| Overseas Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Portfolio of plans			10.00%