Income Taxes Income tax (benefit) provision from continuing operations (Details) (USD $)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)	$ 33,856,000	$ 7,611,000	$ 294,000
Current State and Local Tax Expense (Benefit)	2,350,000	544,000	21,000
Current Foreign Tax Expense (Benefit)	16,950,000	21,174,000	22,877,000
Current Income Tax Expense (Benefit)	53,156,000	29,329,000	23,192,000
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred Federal Income Tax Expense (Benefit)	(16,004,000)	14,942,000	11,035,000
Deferred State and Local Income Tax Expense (Benefit)	(1,111,000)	1,067,000	788,000
Deferred Foreign Income Tax Expense (Benefit)	(11,253,000)	(2,348,000)	(3,484,000)
Deferred Income Tax Expense (Benefit)	(28,368,000)	13,661,000	8,339,000
Income Tax Expense (Benefit), Continuing Operations	24,788,000	42,990,000	31,531,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense		6,300,000	7,500,000
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	53,262,000	132,894,000	161,244,000
Income Tax Reconciliation, State and Local Income Taxes	(2,054,000)	1,280,000	1,746,000
Income Tax Reconciliation, Tax Credits, Research	(8,263,000)	(3,750,000)	(3,691,000)
Income Tax Reconciliation, Tax Credits, Research, Prior Years	(3,347,000)	(5,894,000)	0
Income Tax Reconciliation, Foreign Income Tax Rate Differential	(52,317,000)	(93,905,000)	(92,166,000)
Income Tax Reconciliation, Increases Related to Current and Prior Year Tax Positions	37,507,000	12,365,000	14,330,000
Income Tax Reconciliation, Decreases Related to Prior Year Tax Positions	0	0	(49,932,000)
Income Tax Expense (Benefit), Continuing Operations	24,788,000	42,990,000	31,531,000
Income (Loss) from Continuing Operations before Income Taxes, Foreign	234,300,000	328,500,000	390,900,000
Unremitted Foreign Earnings	1,800,000,000
Tax Adjustments, Settlements, and Unusual Provisions			$ 24,400,000
Effective Income Tax Rate Reconciliation, Other Adjustments			5.30%