Fair Value Measurements (Recorded Amounts of Major Financial Assets and Liabilities Measured at Fair Value on Recurring Basis) (Detail) - JPY (¥) ¥ in Millions		Dec. 31, 2019	Mar. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		¥ 25,583	¥ 27,367
Derivative assets, gross amounts recognized		15,683	15,495
Derivative assets, gross amounts offset in the consolidated balance sheets, assets		(514)	(1,497)
Derivative assets, net amounts presented in the consolidated balance sheets, assets		15,169	13,998
Other assets		9,219	12,449
Derivative liabilities, gross amounts recognized		51,188	25,958
Derivative liabilities, gross amounts offset in the consolidated balance sheets, liabilities		(514)	(1,497)
Derivative liabilities, net amounts presented in the consolidated balance sheets, liabilities		50,674	24,461
Policy Liabilities and Policy Account Balances		333,017	360,198
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		15,683	15,495
Derivative assets, gross amounts offset in the consolidated balance sheets, assets	[1]	(514)	(1,497)
Derivative assets, net amounts presented in the consolidated balance sheets, assets		15,169	13,998
Other assets		9,219	12,449
Total financial assets		2,063,293	1,758,016
Derivative liabilities, gross amounts recognized		51,188	25,958
Derivative liabilities, gross amounts offset in the consolidated balance sheets, liabilities	[1]	(514)	(1,497)
Derivative liabilities, net amounts presented in the consolidated balance sheets, liabilities		50,674	24,461
Policy Liabilities and Policy Account Balances		333,017	360,198
Total financial liabilities		384,205	386,156
Interest rate swap agreements | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		167	138
Derivative liabilities, gross amounts recognized		24,768	17,439
Futures, foreign exchange contracts | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		403	3,007
Derivative liabilities, gross amounts recognized		14,495	5,336
Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[2]	594,755
Equity securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[3],[4]	417,433	425,593
Japanese and foreign government bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[5]	591,235
CMBS and RMBS in the Americas | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		57,962
Options held/written and other | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		13,692	11,140
Derivative liabilities, gross amounts recognized		10,960	2,809
Reinsurance Recoverable
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets		9,219	12,449	[6]
Reinsurance Recoverable | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	[6]	9,219
Credit derivatives held/written | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized			7
Derivative liabilities, gross amounts recognized			10
Variable Annuity and Variable Life Insurance Contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Policy Liabilities and Policy Account Balances		333,017	360,198
Variable Annuity and Variable Life Insurance Contracts | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Policy Liabilities and Policy Account Balances	[7]	333,017	360,198
Loans Held-for-Sale | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[8]	43,238	38,671
Trading securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			1,564
Available-for-sale securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			1,264,244
Available-for-sale securities | Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[2]		487,997
Available-for-sale securities | Japanese and foreign government bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[5]		430,851
Available-for-sale securities | Japanese prefectural and foreign municipal bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		238,288	193,305
Available-for-sale securities | CMBS and RMBS in the Americas | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			61,479
Available-for-sale securities | Other asset-backed securities and debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			90,612
Other securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		94,109
Trading Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		1,371
Available-for-sale Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		1,576,349
Foreign currency swap agreements | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		1,421	1,203
Derivative liabilities, gross amounts recognized		965	364
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, net amounts presented in the consolidated balance sheets, assets	[9]	0	0
Other assets			0
Derivative liabilities, net amounts presented in the consolidated balance sheets, liabilities	[9]	0	0
Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		29	299
Derivative assets, gross amounts offset in the consolidated balance sheets, assets	[1]	0	0
Derivative assets, net amounts presented in the consolidated balance sheets, assets		0
Other assets		0
Total financial assets		95,744	93,761
Derivative liabilities, gross amounts recognized		157	522
Derivative liabilities, gross amounts offset in the consolidated balance sheets, liabilities	[1]	0	0
Derivative liabilities, net amounts presented in the consolidated balance sheets, liabilities		0	0
Policy Liabilities and Policy Account Balances		0	0
Total financial liabilities		157	522
Level 1 | Interest rate swap agreements | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		0	0
Derivative liabilities, gross amounts recognized		0	0
Level 1 | Futures, foreign exchange contracts | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		29	299
Derivative liabilities, gross amounts recognized		157	522
Level 1 | Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[2]	18,796
Level 1 | Equity securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[3],[4]	73,334	68,631
Level 1 | Japanese and foreign government bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[5]	3,585
Level 1 | Japanese prefectural and foreign municipal bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		0
Level 1 | CMBS and RMBS in the Americas | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		0
Level 1 | Options held/written and other | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		0	0
Derivative liabilities, gross amounts recognized		0	0
Level 1 | Reinsurance Recoverable
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	[6]		0
Level 1 | Reinsurance Recoverable | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	[6]	0
Level 1 | Credit derivatives held/written | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized			0
Derivative liabilities, gross amounts recognized			0
Level 1 | Variable Annuity and Variable Life Insurance Contracts | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Policy Liabilities and Policy Account Balances	[7]	0	0
Level 1 | Loans Held-for-Sale | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[8]	0	0
Level 1 | Trading securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			0
Level 1 | Available-for-sale securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			24,831
Level 1 | Available-for-sale securities | Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[2]		21,604
Level 1 | Available-for-sale securities | Japanese and foreign government bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[5]		3,227
Level 1 | Available-for-sale securities | Japanese prefectural and foreign municipal bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			0
Level 1 | Available-for-sale securities | CMBS and RMBS in the Americas | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			0
Level 1 | Available-for-sale securities | Other asset-backed securities and debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			0
Level 1 | Other securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		0
Level 1 | Trading Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		0
Level 1 | Available-for-sale Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		22,381
Level 1 | Foreign currency swap agreements | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		0	0
Derivative liabilities, gross amounts recognized		0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, net amounts presented in the consolidated balance sheets, assets	[9]	0	0
Other assets			0
Derivative liabilities, net amounts presented in the consolidated balance sheets, liabilities	[9]	0	0
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		5,210	9,924
Derivative assets, gross amounts offset in the consolidated balance sheets, assets	[1]	0	0
Derivative assets, net amounts presented in the consolidated balance sheets, assets		0
Other assets		0
Total financial assets		1,780,738	1,484,894
Derivative liabilities, gross amounts recognized		51,004	25,436
Derivative liabilities, gross amounts offset in the consolidated balance sheets, liabilities	[1]	0	0
Derivative liabilities, net amounts presented in the consolidated balance sheets, liabilities		0	0
Policy Liabilities and Policy Account Balances		0	0
Total financial liabilities		51,004	25,436
Level 2 | Interest rate swap agreements | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		167	138
Derivative liabilities, gross amounts recognized		24,768	17,439
Level 2 | Futures, foreign exchange contracts | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		374	2,708
Derivative liabilities, gross amounts recognized		14,338	4,814
Level 2 | Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[2]	571,743
Level 2 | Equity securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[3],[4]	277,917	295,769
Level 2 | Japanese and foreign government bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[5]	587,650
Level 2 | Japanese prefectural and foreign municipal bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		235,437
Level 2 | CMBS and RMBS in the Americas | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		57,962
Level 2 | Options held/written and other | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		3,248	5,868
Derivative liabilities, gross amounts recognized		10,933	2,809
Level 2 | Reinsurance Recoverable
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	[6]		0
Level 2 | Reinsurance Recoverable | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	[6]	0
Level 2 | Credit derivatives held/written | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized			7
Derivative liabilities, gross amounts recognized			10
Level 2 | Variable Annuity and Variable Life Insurance Contracts | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Policy Liabilities and Policy Account Balances	[7]	0	0
Level 2 | Loans Held-for-Sale | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[8]	43,238	38,671
Level 2 | Trading securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			1,564
Level 2 | Available-for-sale securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			1,138,966
Level 2 | Available-for-sale securities | Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[2]		459,235
Level 2 | Available-for-sale securities | Japanese and foreign government bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[5]		427,624
Level 2 | Available-for-sale securities | Japanese prefectural and foreign municipal bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			190,417
Level 2 | Available-for-sale securities | CMBS and RMBS in the Americas | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			61,479
Level 2 | Available-for-sale securities | Other asset-backed securities and debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			211
Level 2 | Other securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		210
Level 2 | Trading Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		1,371
Level 2 | Available-for-sale Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		1,453,002
Level 2 | Foreign currency swap agreements | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		1,421	1,203
Derivative liabilities, gross amounts recognized		965	364
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, net amounts presented in the consolidated balance sheets, assets	[9]	0	0
Other assets			12,449
Total financial assets		186,811	179,361
Derivative liabilities, net amounts presented in the consolidated balance sheets, liabilities	[9]	0	0
Total financial liabilities		333,044	360,198
Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		10,444	5,272
Derivative assets, gross amounts offset in the consolidated balance sheets, assets	[1]	0	0
Derivative assets, net amounts presented in the consolidated balance sheets, assets		0
Other assets		9,219
Total financial assets		186,811	179,361
Derivative liabilities, gross amounts recognized		27	0
Derivative liabilities, gross amounts offset in the consolidated balance sheets, liabilities	[1]	0	0
Derivative liabilities, net amounts presented in the consolidated balance sheets, liabilities		0	0
Policy Liabilities and Policy Account Balances		333,017	360,198
Total financial liabilities		333,044	360,198
Level 3 | Interest rate swap agreements | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		0	0
Derivative liabilities, gross amounts recognized		0	0
Level 3 | Futures, foreign exchange contracts | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		0	0
Derivative liabilities, gross amounts recognized		0	0
Level 3 | Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[2]	4,216
Level 3 | Equity securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[3],[4]	66,182	61,193
Level 3 | Japanese and foreign government bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[5]	0
Level 3 | Japanese prefectural and foreign municipal bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		2,851
Level 3 | CMBS and RMBS in the Americas | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		0
Level 3 | Options held/written and other | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		10,444	5,272
Derivative liabilities, gross amounts recognized		27	0
Level 3 | Reinsurance Recoverable
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	[6]		12,449
Level 3 | Reinsurance Recoverable | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other assets	[6]	9,219
Level 3 | Credit derivatives held/written | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized			0
Derivative liabilities, gross amounts recognized			0
Level 3 | Variable Annuity and Variable Life Insurance Contracts | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Policy Liabilities and Policy Account Balances	[7]	333,017	360,198
Level 3 | Loans Held-for-Sale | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[8]	0	0
Level 3 | Trading securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			0
Level 3 | Available-for-sale securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			100,447
Level 3 | Available-for-sale securities | Corporate debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[2]		7,158
Level 3 | Available-for-sale securities | Japanese and foreign government bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments	[5]		0
Level 3 | Available-for-sale securities | Japanese prefectural and foreign municipal bond securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			2,888
Level 3 | Available-for-sale securities | CMBS and RMBS in the Americas | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			0
Level 3 | Available-for-sale securities | Other asset-backed securities and debt securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments			90,401
Level 3 | Other securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		93,899
Level 3 | Trading Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		0
Level 3 | Available-for-sale Debt Securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Fair value measured on recurring basis investments		100,966
Level 3 | Foreign currency swap agreements | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets, gross amounts recognized		0	0
Derivative liabilities, gross amounts recognized		¥ 0	¥ 0

[1] It represents the amount offset under counterparty netting of derivative assets and liabilities.

[2] A certain subsidiary elected the fair value option for investments in foreign corporate debt securities included in available-for-sale debt securities. Included in “Gains on investment securities and dividends” in the consolidated statements of income were losses of ¥136 million and ¥0 million from the change in the fair value of those investments for the nine months ended December 31, 2018 and 2019, respectively. Included in “Gains on investment securities and dividends” in the consolidated statements of income were losses of ¥393 million and ¥0 million from the change in the fair value of those investments for the three months ended December 31, 2018 and 2019, respectively. The amounts of aggregate fair value elected the fair value option were ¥21,136 million and ¥0 million as of March 31, 2019 and December 31, 2019, respectively.

[3] Certain subsidiaries elected the fair value option for certain investments in investment funds included in equity securities. Included in “Gains on investment securities and dividends” in the consolidated statements of income were gains of ¥906 million and ¥0 million from the change in the fair value of those investments for the nine months ended December 31, 2018 and 2019, respectively. Included in “Gains on investment securities and dividends” in the consolidated statements of income were gains of ¥265 million and ¥0 million from the change in the fair value of those investments for the three months ended December 31, 2018 and 2019, respectively. The amounts of aggregate fair value elected the fair value option were ¥5,811 million and ¥0 million as of March 31, 2019 and December 31, 2019, respectively.

[4] The amounts of investment funds measured at net asset value per share which are not included in the above tables were ¥12,100 million and ¥0 as of March 31, 2019 and December 31, 2019, respectively.

[5] A certain subsidiary elected the fair value option for investments in foreign government bond securities included in available-for-sale debt securities. Included in “Gains on investment securities and dividends” in the consolidated statements of income were losses of ¥21 million and ¥0 million from the change in the fair value of those investments for the nine months ended December 31, 2018 and 2019, respectively. Included in “Gains on investment securities and dividends” in the consolidated statements of income were losses of ¥12 million and ¥0 from the change in the fair value of those investments for the three months ended December 31, 2018 and 2019, respectively. The amounts of aggregate fair value elected the fair value option were ¥420 million and ¥0 million as of March 31, 2019 and December 31, 2019, respectively.

[6] Certain subsidiaries elected the fair value option for certain reinsurance contracts held. The fair value of the reinsurance contracts elected for the fair value option in other assets were ¥12,449 million and ¥0 million as of March 31, 2019 and December 31, 2019, respectively. For the effect of changes in the fair value of those reinsurance contracts on earnings during the nine and three months ended December 31, 2018 and 2019, see Note 17 “Life Insurance Operations.”

[7] Certain subsidiaries elected the fair value option for the entire variable annuity and variable life insurance contracts held in order to match the earnings recognized for the changes in the fair value of policy liabilities and policy account balances with earnings recognized for gains or losses from the investment assets managed on behalf of variable annuity and variable life policyholders, derivative contracts and the changes in the fair value of reinsurance contracts. The fair value of the variable annuity and variable life insurance contracts elected for the fair value option in policy liabilities and policy account balances were ¥360,198 million and ¥0 million as of March 31, 2019 and December 31, 2019, respectively. For the effect of changes in the fair value of the variable annuity and variable life insurance contracts on earnings during the nine and three months ended December 31, 2018 and 2019, see Note 17 “Life Insurance Operations.”

[8] A certain subsidiary elected the fair value option on certain loans held for sale. These loans are multi-family and seniors housing loans and are sold to Federal National Mortgage Association (“Fannie Mae”) or institutional investors. Included in “Other (income) and expense, net” in the consolidated statements of income were gains of ¥495 million and ¥0 million from the change in the fair value of the loans for the nine months ended December 31, 2018 and 2019, respectively. Included in “Other (income) and expense, net” in the consolidated statements of income were a gain of ¥294 million and a loss of ¥0 million from the change in the fair value of the loans for the three months ended December 31, 2018 and 2019, respectively. No gains or losses were recognized in earnings during the nine months ended December 31, 2018 and 2019 attributable to changes in instrument-specific credit risk. The amounts of aggregate unpaid principal balance and aggregate fair value of the loans held for sale as of March 31, 2019, were ¥37,865 million and ¥38,671 million, respectively, and the amount of the aggregate fair value exceeded the amount of aggregate unpaid principal balance by ¥806 million. The amounts of aggregate unpaid principal balance and aggregate fair value of the loans held for sale as of December 31, 2019, were ¥0 million and ¥0 million, respectively, and the amount of the aggregate fair value exceeded the amount of aggregate unpaid principal balance by ¥0 million. As of March 31, 2019 and December 31, 2019, there were no loans that are 90 days or more past due or, in non-accrual status.

[9] It represents the amount after offset under counterparty netting of derivative assets and liabilities. For the information of input level before netting, see Note 3 “Fair Value Measurements.”