Income Taxes Income tax (benefit) provision from continuing operations (Details) (USD $)	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)	$ 992,000	$ 33,856,000	$ 7,611,000
Current State and Local Tax Expense (Benefit)	64,000	2,350,000	544,000
Current Foreign Tax Expense (Benefit)	30,697,000	16,950,000	21,174,000
Current Income Tax Expense (Benefit)	31,753,000	53,156,000	29,329,000
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred Federal Income Tax Expense (Benefit)	14,445,000	(16,004,000)	14,942,000
Deferred State and Local Income Tax Expense (Benefit)	929,000	(1,111,000)	1,067,000
Deferred Foreign Income Tax Expense (Benefit)	(10,054,000)	(11,253,000)	(2,348,000)
Deferred Income Tax Expense (Benefit)	5,320,000	(28,368,000)	13,661,000
Income tax provision	37,073,000	24,788,000	42,990,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	1,400,000		11,000,000
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	151,324,000	53,262,000	132,894,000
Income Tax Reconciliation, State and Local Income Taxes	686,000	(2,054,000)	1,280,000
Research and development tax credits - current year	(4,875,000)	(8,263,000)	(3,750,000)
Research and development tax credits - prior years	1,600,000	(3,347,000)	(5,894,000)
Income Tax Reconciliation, Foreign Income Tax Rate Differential	(116,003,000)	(61,377,000)	(97,169,000)
Income Tax Reconciliation, Increases Related to Current and Prior Year Tax Positions	16,809,000	44,661,000	14,518,000
Income Tax Reconciliation, Decreases Related to Prior Year Tax Positions	(14,581,000)	(7,154,000)	(2,153,000)
Withholding taxes	6,212,000	7,267,000	6,995,000
Other	(4,099,000)	1,793,000	(3,731,000)
Income Tax Expense (Benefit), Continuing Operations	37,073,000	24,788,000	42,990,000
Increase of basic and diluted net income per common share due to release of prior year tax positions	$ 0.07		$ 0.01
Increase of basic net income per share due to release of prior year tax positions		$ 0.04
Increase of diluted net income per share due to release of prior year tax positions		$ 0.03
Income (Loss) from Continuing Operations before Income Taxes, Foreign	404,100,000	234,300,000	328,500,000
Unremitted Foreign Earnings	2,400,000,000
Tax Adjustments, Settlements, and Unusual Provisions	14,600,000
Effective Income Tax Rate Reconciliation, Other Adjustments			3.40%
One time tax benefit relating to reinstatement of research and development tax		$ 8,100,000