Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 29, 2018	Mar. 31, 2018
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale Securities, Noncurrent	$ 91,627	$ 97,896
Fair Value, Measurements, Recurring [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	3,303,728	3,476,786
Fair Value, Net Asset (Liability)	3,255,937	3,450,695
Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Assets [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Liabilities, Fair Value Disclosure, Recurring	47,791	26,091
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	500,928	1,304,752
Fair Value, Net Asset (Liability)	500,928	1,304,752
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Assets [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	2,802,800	2,172,034
Fair Value, Net Asset (Liability)	2,755,009	2,145,943
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Assets [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Liabilities, Fair Value Disclosure, Recurring	47,791	26,091
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Net Asset (Liability)	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Assets [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Liabilities, Fair Value Disclosure, Recurring	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Money Market Funds [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	376,673	1,291,891
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	403,980	359,901
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Non-financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	476,957	242,904
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | U.S. Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	277,778	35,995
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Foreign Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	370,791	179,957
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	376,673	1,291,891
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Non-financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	114,891	996
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	403,980	359,901
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Non-financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	476,957	242,904
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	162,887	34,999
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	370,791	179,957
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Non-financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Cash And Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	225,000	75,000
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Non-financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	96,379	81,939
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | U.S. Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	15,507	22,647
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Mortgage-Backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	749,426	844,397
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Asset-backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	85,421	91,389
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Commercial Mortgage Backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	134,189	152,870
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Non-financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	2,663	3,639
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Mortgage-Backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Asset-backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Mortgage Backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | Financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	225,000	75,000
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | Non-financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	96,379	81,939
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	12,844	19,008
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | Mortgage-Backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	749,426	844,397
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	85,421	91,389
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Mortgage Backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	134,189	152,870
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Non-financial institution securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Government and Agency Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Mortgage-Backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Short-Term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Mortgage Backed Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Long-Term Investments [Member] | Debt Mutual Fund [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	84,926	89,670
Fair Value, Measurements, Recurring [Member] | Long-Term Investments [Member] | Equity Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	6,701	8,226
Fair Value, Measurements, Recurring [Member] | Long-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Mutual Fund [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Long-Term Investments [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	6,701	8,226
Fair Value, Measurements, Recurring [Member] | Long-Term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Mutual Fund [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	84,926	89,670
Fair Value, Measurements, Recurring [Member] | Long-Term Investments [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0
Fair Value, Measurements, Recurring [Member] | Long-Term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Mutual Fund [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Long-Term Investments [Member] | Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Assets measured at fair value	0	0
Other Noncurrent Liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Derivative Financial Instruments, Assets [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Liabilities, Fair Value Disclosure, Recurring	47,791	26,091
Other Noncurrent Liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Derivative Financial Instruments, Assets [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Liabilities, Fair Value Disclosure, Recurring	0	0
Other Noncurrent Liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Derivative Financial Instruments, Assets [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Liabilities, Fair Value Disclosure, Recurring	47,791	26,091
Other Noncurrent Liabilities [Member] | Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Assets [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Liabilities, Fair Value Disclosure, Recurring	$ 0	$ 0