Long-Term Debt Schedule of Current Value of Long-term Debt (Details) - Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Mar. 31, 2015
Debt Instrument
Long-term Debt	$ 1,057,122	$ 1,058,089
Derivative Instruments in Hedges, Assets, at Fair Value	(4,487)
Debt Instrument, Unamortized Discount (Premium), Net	(2,635)
Long-term Debt, Gross	1,050,000
2.7% Senior Notes [Member]
Debt Instrument
Long-term Debt	254,045	254,993
Derivative Instruments in Hedges, Assets, at Fair Value	(4,487)
Debt Instrument, Unamortized Discount	442
Long-term Debt, Gross	250,000
3.95% Senior Notes [Member]
Debt Instrument
Long-term Debt	249,589	249,577
Derivative Instruments in Hedges, Assets, at Fair Value	0
Debt Instrument, Unamortized Discount	411
Long-term Debt, Gross	250,000
5.625% senior notes
Debt Instrument
Long-term Debt	553,488	$ 553,519
Derivative Instruments in Hedges, Assets, at Fair Value	0
Debt Instrument, Unamortized Premium	(3,488)
Long-term Debt, Gross	$ 550,000

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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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The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

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The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

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The amount of debt premium that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Aggregate fair value of all derivative assets designated as hedging instruments. Includes instruments designated as cash flow hedges, fair value hedges, and hedges of net investments in foreign operations.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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