Fair Value Measurements - Assets and Liabilities that are Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Feb. 03, 2018	Jan. 28, 2017
Assets
Investments	$ 952,790	$ 858,883
Fair Value
Assets
Total assets	1,221,261	1,022,493
Fair Value \| Foreign currency forward contracts
Liabilities
Accrued liabilities		58
Fair Value \| Prepaid expenses and other current assets \| Foreign currency forward contracts
Assets
Prepaid expenses and other current assets		735
Fair Value \| Other non-current assets \| Severance pay fund
Assets
Other non-current assets	896	736
Fair Value \| Money market funds
Assets
Cash equivalents	18,503	36,122
Fair Value \| Time deposits
Assets
Cash equivalents	65,117	67,000
Fair Value \| Time deposits \| Short-term investments
Assets
Investments	150,000	150,000
Fair Value \| U.S. government and agency debt
Assets
Cash equivalents	51,589	17,497
Fair Value \| U.S. government and agency debt \| Short-term investments
Assets
Investments	247,741	185,387
Fair Value \| Foreign government and agency debt
Assets
Cash equivalents		1,500
Fair Value \| Foreign government and agency debt \| Short-term investments
Assets
Investments	6,987	13,375
Fair Value \| Municipal debt securities
Assets
Cash equivalents	5,290	8,740
Fair Value \| Municipal debt securities \| Short-term investments
Assets
Investments	2,728	27,871
Fair Value \| Corporate debt securities
Assets
Cash equivalents	127,076	31,280
Fair Value \| Corporate debt securities \| Short-term investments
Assets
Investments	503,079	432,108
Fair Value \| Asset backed securities \| Short-term investments
Assets
Investments	42,255	45,527
Fair Value \| Auction rate securities \| Long-term investments
Assets
Investments		4,615
Fair Value \| Level 1
Assets
Total assets	317,833	239,006
Fair Value \| Level 1 \| Foreign currency forward contracts
Liabilities
Accrued liabilities		0
Fair Value \| Level 1 \| Prepaid expenses and other current assets \| Foreign currency forward contracts
Assets
Prepaid expenses and other current assets		0
Fair Value \| Level 1 \| Other non-current assets \| Severance pay fund
Assets
Other non-current assets	0	0
Fair Value \| Level 1 \| Money market funds
Assets
Cash equivalents	18,503	36,122
Fair Value \| Level 1 \| Time deposits
Assets
Cash equivalents	0	0
Fair Value \| Level 1 \| Time deposits \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 1 \| U.S. government and agency debt
Assets
Cash equivalents	51,589	17,497
Fair Value \| Level 1 \| U.S. government and agency debt \| Short-term investments
Assets
Investments	247,741	185,387
Fair Value \| Level 1 \| Foreign government and agency debt
Assets
Cash equivalents		0
Fair Value \| Level 1 \| Foreign government and agency debt \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 1 \| Municipal debt securities
Assets
Cash equivalents	0	0
Fair Value \| Level 1 \| Municipal debt securities \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 1 \| Corporate debt securities
Assets
Cash equivalents	0	0
Fair Value \| Level 1 \| Corporate debt securities \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 1 \| Asset backed securities \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 1 \| Auction rate securities \| Long-term investments
Assets
Investments		0
Fair Value \| Level 2
Assets
Total assets	903,428	778,872
Fair Value \| Level 2 \| Foreign currency forward contracts
Liabilities
Accrued liabilities		58
Fair Value \| Level 2 \| Prepaid expenses and other current assets \| Foreign currency forward contracts
Assets
Prepaid expenses and other current assets		735
Fair Value \| Level 2 \| Other non-current assets \| Severance pay fund
Assets
Other non-current assets	896	736
Fair Value \| Level 2 \| Money market funds
Assets
Cash equivalents	0	0
Fair Value \| Level 2 \| Time deposits
Assets
Cash equivalents	65,117	67,000
Fair Value \| Level 2 \| Time deposits \| Short-term investments
Assets
Investments	150,000	150,000
Fair Value \| Level 2 \| U.S. government and agency debt
Assets
Cash equivalents	0	0
Fair Value \| Level 2 \| U.S. government and agency debt \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 2 \| Foreign government and agency debt
Assets
Cash equivalents		1,500
Fair Value \| Level 2 \| Foreign government and agency debt \| Short-term investments
Assets
Investments	6,987	13,375
Fair Value \| Level 2 \| Municipal debt securities
Assets
Cash equivalents	5,290	8,740
Fair Value \| Level 2 \| Municipal debt securities \| Short-term investments
Assets
Investments	2,728	27,871
Fair Value \| Level 2 \| Corporate debt securities
Assets
Cash equivalents	127,076	31,280
Fair Value \| Level 2 \| Corporate debt securities \| Short-term investments
Assets
Investments	503,079	432,108
Fair Value \| Level 2 \| Asset backed securities \| Short-term investments
Assets
Investments	42,255	45,527
Fair Value \| Level 2 \| Auction rate securities \| Long-term investments
Assets
Investments		0
Fair Value \| Level 3
Assets
Total assets	0	4,615
Fair Value \| Level 3 \| Foreign currency forward contracts
Liabilities
Accrued liabilities		0
Fair Value \| Level 3 \| Prepaid expenses and other current assets \| Foreign currency forward contracts
Assets
Prepaid expenses and other current assets		0
Fair Value \| Level 3 \| Other non-current assets \| Severance pay fund
Assets
Other non-current assets	0	0
Fair Value \| Level 3 \| Money market funds
Assets
Cash equivalents	0	0
Fair Value \| Level 3 \| Time deposits
Assets
Cash equivalents	0	0
Fair Value \| Level 3 \| Time deposits \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 3 \| U.S. government and agency debt
Assets
Cash equivalents	0	0
Fair Value \| Level 3 \| U.S. government and agency debt \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 3 \| Foreign government and agency debt
Assets
Cash equivalents		0
Fair Value \| Level 3 \| Foreign government and agency debt \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 3 \| Municipal debt securities
Assets
Cash equivalents	0	0
Fair Value \| Level 3 \| Municipal debt securities \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 3 \| Corporate debt securities
Assets
Cash equivalents	0	0
Fair Value \| Level 3 \| Corporate debt securities \| Short-term investments
Assets
Investments	0	0
Fair Value \| Level 3 \| Asset backed securities \| Short-term investments
Assets
Investments	$ 0	0
Fair Value \| Level 3 \| Auction rate securities \| Long-term investments
Assets
Investments		$ 4,615

Fair value portion of accrued expenses.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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Fair value portion of other assets.

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