Fair Value Measurement - Securities Carried at Amortized Cost Plus Accrued Interest (Details) - USD ($) $ in Thousands	Jul. 29, 2017	Jan. 28, 2017
Investment securities classified as held to maturity
Amortized Cost	$ 59,417	$ 64,717
Total Fair Market Value	59,351	64,668
Short-term Investments
Investment securities classified as held to maturity
Amortized Cost	32,669	38,026
Gross Unrealized Gains	1	3
Gross Unrealized Losses	(12)	(1)
Total Fair Market Value	32,658	38,028
Short-term Investments \| Obligations of the U.S. Treasury \| Fair Value, Inputs, Level 1
Investment securities classified as held to maturity
Amortized Cost	10,398	9,995
Gross Unrealized Gains		1
Gross Unrealized Losses	(12)
Total Fair Market Value	10,386	9,996
Short-term Investments \| Obligations of states and municipalities \| Fair Value, Inputs, Level 2
Investment securities classified as held to maturity
Amortized Cost	6,676	14,816
Gross Unrealized Gains	1	2
Gross Unrealized Losses		(1)
Total Fair Market Value	6,677	14,817
Short-term Investments \| Bank certificates of deposit \| Fair Value, Inputs, Level 2
Investment securities classified as held to maturity
Amortized Cost	15,595	13,215
Total Fair Market Value	15,595	13,215
Long Term Investments
Investment securities classified as held to maturity
Amortized Cost	26,748	26,691
Gross Unrealized Losses	(55)	(51)
Total Fair Market Value	26,693	26,640
Long Term Investments \| Obligations of the U.S. Treasury \| Fair Value, Inputs, Level 1
Investment securities classified as held to maturity
Amortized Cost	14,971	15,011
Gross Unrealized Losses	(55)	(51)
Total Fair Market Value	14,916	14,960
Long Term Investments \| Bank certificates of deposit \| Fair Value, Inputs, Level 2
Investment securities classified as held to maturity
Amortized Cost	11,717	11,680
Total Fair Market Value	$ 11,717	$ 11,680

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.6)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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