Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

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-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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- Definition

Amount, after accumulated amortization, of debt premium.

+ References

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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- Definition

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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-Name Accounting Standards Codification
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-Section S99
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-Subparagraph (SX 210.12-04.(a))
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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

The cash outflow for incremental, external costs directly pertaining to an early extinguishment of debt, including legal costs and prepayment penalties, and excluding interest and repayment of debt principal.

+ References

No definition available.

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- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

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The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

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Short-Term Borrowings and Long-Term Debt Long Term Debt Information (Details) - USD ($)	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2016	Mar. 31, 2016	Mar. 22, 2016	Mar. 14, 2016	Jun. 26, 2014	Jan. 31, 2014
Debt Instrument [Line Items]
Debt Instrument, Convertible, Conversion Price	$ 88
Payments of Debt Extinguishment Costs		$ 107,074,000
Debt Instrument, Unamortized Discount								$ 553,000
Debt Instrument, Basis Spread on Variable Rate	1.25%
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 2,250,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Three	250,000,000
Long-term Debt, Maturities, Repayments of Principal after Year Five	2,000,000,000
Long-term Debt, Fair Value	2,264,867,000				$ 1,773,852,000
5.625% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Unamortized Premium								$ 9,779,000
Debt Instrument, Interest Rate, Stated Percentage								5.625%
Debt Instrument, Unamortized Discount								$ 6,260,000
5.625% Senior Notes [Member] \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	550,000,000							$ 150,000,000	$ 400,000,000
Debt Instrument, Unamortized Premium	(3,274,000)
5.45% Junior Subordinated Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				5.45%
5.45% Junior Subordinated Notes [Member] \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	500,000,000			$ 500,000,000
Debt Instrument, Unamortized Premium	0
3.95% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage								3.95%
Debt Instrument, Unamortized Discount								$ 458,000.0000
3.95% Senior Notes [Member] \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	250,000,000
Debt Instrument, Unamortized Discount	332,000
2.7% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage								2.70%
Proceeds from Issuance of Debt		658,769,000
2.7% Senior Notes [Member] \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	250,000,000
Debt Instrument, Unamortized Discount	250,000
Five-year term loan [Member]
Debt Instrument [Line Items]
Repayments of Debt			$ 450,000,000
5.5% Senior Notes [Member] \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross								$ 650,000,000
4.75% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						4.75%
Debt Instrument, Unamortized Discount						$ 207,000.0000
4.75% Senior Notes [Member] \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	450,000,000
Debt Instrument, Unamortized Premium	0
6.375% Junior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage							6.375%
6.375% Junior Notes [Member] \| Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	250,000,000
Debt Instrument, Unamortized Premium	$ 0
Make Whole Premium [Member]
Debt Instrument [Line Items]
Payments of Debt Extinguishment Costs		98,418,000
Non-Cash Write-off [Member]
Debt Instrument [Line Items]
Payments of Debt Extinguishment Costs		$ 8,656,000
US Treasury Interest Rate [Member] \| 5.625% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.30%
US Treasury Interest Rate [Member] \| 3.95% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.25%
US Treasury Interest Rate [Member] \| 2.7% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.20%
US Treasury Interest Rate [Member] \| 4.75% Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.45%