Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income
CASH FLOWS FROM FINANCING ACTIVITIES
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(12,821)	$ (14,063)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests		(8,789)
Cash Acquired from Acquisition	992
Consolidated Legg Mason, Inc.
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	55,074	61,569
Adjustments to reconcile Net Income to net cash used in operations:
Depreciation and amortization	19,448	16,496
Accretion and amortization of securities discounts and premiums, net	427	108
Stock-based compensation	7,421	23,834
Deferred income taxes	9,026	22,294
Contingent consideration fair value adjustments	0	(1,165)
Other	(21)	345
Decrease (increase) in assets:
Investment advisory and related fees receivable	2,639	235
Net (purchases) sales of trading and other current investments	(42,790)	(4,817)
Other receivables	(1,638)	10,661
Increase (decrease) in liabilities:
Accrued compensation	(314,376)	(300,250)
Deferred compensation	9,061	12,084
Accounts payable and accrued expenses	8,558	(10,298)
CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES	(211,492)	(187,577)
CASH FLOWS FROM INVESTING ACTIVITIES
Payments for fixed assets	(5,762)	(9,190)
Payments to Acquire Equity Method Investments	(250)
Payments to Acquire Businesses, Net of Cash Acquired	0	(10,247)
CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	(5,947)	(18,949)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from Short-term Debt	250,000	0
Dividends paid	(36,266)	(30,131)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(13,676)	(16,230)
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	0	(10,548)
Employee Tax Withholdings Related to net share transaction	(37,152)	(12,581)
Issuance of common stock for stock-based compensation	53,437	9,599
CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	121,115	(68,123)
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	(945)	(2,697)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	(97,269)	(277,346)
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	1,049,677	950,795
Cash, Cash Equivalents, and Restricted Cash, End of Period	952,408	673,449
Income Taxes Paid, Net	4,587	4,776
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	10,947	11,081
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	54,176	55,092
Adjustments to reconcile Net Income to net cash used in operations:
Net unrealized losses (gains) on investments	(40,022)	(4,684)
Net losses (gains) on investments	11,830	(6,748)
Decrease (increase) in assets:
Other assets	(15,379)	(5,294)
Increase (decrease) in liabilities:
Other liabilities	(24,260)	(5,398)
CASH FLOWS FROM INVESTING ACTIVITIES
Proceeds from Sale, Maturity and Collection of Investments	65	488
CASH FLOWS FROM FINANCING ACTIVITIES
Cash and Cash Equivalents	931,605	643,574
Restricted Cash and Cash Equivalents, Current	20,496	22,201
Restricted Cash and Cash Equivalents, Noncurrent	72	2,888
Consolidated Investment Vehicles [Member]
Adjustments to reconcile Net Income to net cash used in operations:
Net losses (gains) on investments	2,158	(9,561)
Decrease (increase) in assets:
Other assets	102,120	11,400
Increase (decrease) in liabilities:
Other liabilities	(768)	1,612
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from (Payments to) Noncontrolling Interests	(95,228)	(8,232)
Cash and Cash Equivalents	235	4,786
Consolidated Legg Mason, Inc.
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	55,074	61,569
Adjustments to reconcile Net Income to net cash used in operations:
Contingent consideration fair value adjustments	$ 0	$ (1,165)