Income Taxes - Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Income (Loss) Before Income Taxes [Abstract]
Domestic	$ 181,730	$ 71,482	$ (69,997)
Foreign	147,204	149,214	63,011
Income (loss) before income taxes	328,934	220,696	(6,986)
Intercompany dividends	130,000	250,000	13,692
Current
Federal	33,334	80,339	2,184
State	9,084	3,437	1,576
Foreign	15,269	14,388	8,039
Total	57,687	98,164	11,799
Deferred
Federal	6,612	12,007	(20,287)
State	2,236	391	(3,446)
Foreign	(1,909)	(4,260)	(762)
Total	6,939	8,138	(24,495)
Income tax expense (benefit)	64,626	106,302	(12,696)
Actual income taxes differed from that obtained by applying the statutory federal income tax rate to income before income taxes
Computed expected income taxes	69,076	69,556	(2,445)
State income taxes, net of federal income tax benefit	9,329	9,044	(1,403)
Foreign rate differential	(20,105)	(37,090)	(8,062)
Unrecognized tax benefits	786	1,301	2,691
Income tax expense on diminution of operations and nondeductible goodwill	0	0	3,921
Return to provision adjustments	(179)	(2,252)	(1,386)
Nontaxable income	(4,257)	(7,006)	(5,055)
Nondeductible expense	7,742	1,382	1,358
US tax on deemed repatriated foreign earnings	5,848	57,138	0
Re-measurement of deferred taxes	(983)	14,395	0
Statutory foreign income tax expense (benefit)	276	59	(2,504)
Other	(2,907)	(225)	189
Income tax expense (benefit)	$ 64,626	106,302	$ (12,696)
Income Tax Contingency [Line Items]
Provisional transition tax		59,114
State Tax Authority
Income Tax Contingency [Line Items]
Provisional transition tax		$ 1,976