Income Taxes Income tax (benefit) provision from continuing operations (Details) (USD $)	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)	$ 7,611,000	$ 294,000	$ (4,358,000)
Current State and Local Tax Expense (Benefit)	544,000	21,000	(436,000)
Current Foreign Tax Expense (Benefit)	21,174,000	22,877,000	6,981,000
Current Income Tax Expense (Benefit)	29,329,000	23,192,000	2,187,000
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred Federal Income Tax Expense (Benefit)	14,942,000	11,035,000	16,663,000
Deferred State and Local Income Tax Expense (Benefit)	1,067,000	788,000	1,668,000
Deferred Foreign Income Tax Expense (Benefit)	(2,348,000)	(3,484,000)	290,000
Deferred Income Tax Expense (Benefit)	13,661,000	8,339,000	18,621,000
Income Tax Expense (Benefit), Continuing Operations	42,990,000	31,531,000	20,808,000
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	11,000,000	7,500,000	3,700,000
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	132,894,000	161,244,000	83,235,000
Income Tax Reconciliation, State and Local Income Taxes	1,280,000	1,746,000	915,000
Income Tax Reconciliation, Tax Credits, Research	(3,750,000)	(3,691,000)	(1,500,000)
Income Tax Reconciliation, Tax Credits, Research, Prior Years	(5,894,000)	0	0
Income Tax Reconciliation, Foreign Income Tax Rate Differential	(81,540,000)	(103,373,000)	(53,390,000)
Income Tax Reconciliation, Tax Settlements	0	(24,395,000)	(8,452,000)
Income Tax Expense (Benefit), Continuing Operations	42,990,000	31,531,000	20,808,000
Income (Loss) from Continuing Operations before Income Taxes, Foreign	328,500,000	390,900,000	201,200,000
Unremitted Foreign Earnings	$ 1,900,000,000
Effective Income Tax Rate Reconciliation, Tax Settlements		5.30%	3.60%