Retirement And Severance Benefits (Amounts Recognized In Accumulated Other Comprehensive Income (Loss) (Detail) (JPY ¥) In Millions, unless otherwise specified	Mar. 31, 2012	Mar. 31, 2011
Retirement And Severance Benefits [Abstract]
Prior service benefit	¥ (122,795)	¥ (172,964)
Actuarial loss	588,447	530,195
Amounts recognized in accumulated other comprehensive income (loss)	¥ 465,652	¥ 357,231

The pretax net amount of gains and losses that are not yet recognized as a component of net periodic benefit cost, and that are recognized as increases or decreases in other comprehensive income as they arise. Gains and losses are due to changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.

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Amount related to the pretax cost of benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, which has not yet been recognized as components of net periodic benefit cost.

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