Income Taxes Schedule of Deferred Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Schedule of Deferred Tax Assets [Line Items]
Deferred Tax Assets, Charitable Contribution Carryforwards	$ 4,552	$ 0
Deferred Tax Assets, Unrealized Losses on Trading Securities	4,389	0
Deferred Tax Assets, Investment in Subsidiaries	0	4,174
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits	185,311	158,369
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities	50,865	60,282
Deferred Tax Assets, Operating Loss Carryforwards	273,133	290,765
Deferred Tax Assets, Capital Loss Carryforwards	3,121	5,335
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	258,486	247,027
Deferred Tax Assets, Other	5,181	0
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pensions	5,896	7,741
Deferred Tax Assets, Gross	833,458	823,122
Foreign Earnings	740,000
Deferred Tax Assets, Valuation Allowance	(79,476)	(96,687)
Deferred Tax Assets, Net of Valuation Allowance	753,982	726,435
Deferred Tax Liabilities, Goodwill and Intangible Assets	56,625	82,636
Deferred Tax Liabilities, Property, Plant and Equipment	686,421	666,057
Deferred Tax Liabilities, Unrealized Gains on Trading Securities	0	7,832
Deferred Tax Liabilities, Other	0	435
Deferred Tax Liabilities, Deferred Expense	807,571	756,960
Deferred Tax Liabilities, Net	53,589	30,525
Federal Benefit of Uncertain Tax Positions [Member]
Schedule of Deferred Tax Assets [Line Items]
Deferred Tax Assets, Other	12,290	18,461
Fund Launch Costs [Member]
Schedule of Deferred Tax Assets [Line Items]
Deferred Tax Assets, Other	30,234	30,968
Valuation Allowance, Operating Loss Carryforwards [Member]
Schedule of Deferred Tax Assets [Line Items]
Income Tax Expense (Benefit)	22,585
Domestic Tax Authority [Member]
Schedule of Deferred Tax Assets [Line Items]
Deferred Tax Assets, Charitable Contribution Carryforwards	4,552	233
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	258,486	247,027
Deferred Tax Assets, Gross	711,535
Deferred Tax Assets, Valuation Allowance	(20,950)
Valuation Allowances and Reserves, Period Increase (Decrease)	6,916
Domestic Tax Authority [Member] | Contribution of Monetary Assets by an Enterprise to a Charitable Organization [Domain]
Schedule of Deferred Tax Assets [Line Items]
Valuation Allowances and Reserves, Period Increase (Decrease)	3,443
Domestic Tax Authority [Member] | Foreign Tax Credit Release [Domain]
Schedule of Deferred Tax Assets [Line Items]
Valuation Allowances and Reserves, Deductions	12,677
Domestic Tax Authority [Member] | Foreign Tax Authority [Member]
Schedule of Deferred Tax Assets [Line Items]
Valuation Allowances and Reserves, Period Increase (Decrease)	2,500
Foreign Tax Authority [Member]
Schedule of Deferred Tax Assets [Line Items]
Deferred Tax Assets, Capital Loss Carryforwards	3,077	5,290
Valuation Allowances and Reserves, Period Increase (Decrease)	11,438
Foreign Tax Authority [Member] | Foreign Tax Authority [Member]
Schedule of Deferred Tax Assets [Line Items]
Valuation Allowances and Reserves, Period Increase (Decrease)	23,465
State and Local Jurisdiction [Member]
Schedule of Deferred Tax Assets [Line Items]
Deferred Tax Assets, Capital Loss Carryforwards	44	44
Deferred Tax Assets, Gross	175,749
Valuation Allowances and Reserves, Period Increase (Decrease)	26,816
Martin Currie [Member] | Domestic Tax Authority [Member] | Valuation Allowance, Operating Loss Carryforwards [Member]
Schedule of Deferred Tax Assets [Line Items]
Valuation Allowances and Reserves, Period Increase (Decrease)	973
Subsidiaries [Member]
Schedule of Deferred Tax Assets [Line Items]
Deferred Tax Liabilities, Net	(68,526)
Deferred Tax Liabilities, Investments	64,525	$ 0
UNITED STATES
Schedule of Deferred Tax Assets [Line Items]
U.S. Earnings	$ 3,200,000