Fair Value Measurement - Securities Carried at Amortized Cost Plus Accrued Interest (Details) - USD ($) $ in Thousands	Apr. 29, 2017	Jan. 28, 2017
Investment securities classified as held to maturity
Amortized Cost	$ 60,103	$ 64,717
Total Fair Market Value	60,038	64,668
Short-term Investments
Investment securities classified as held to maturity
Amortized Cost	34,189	38,026
Gross Unrealized Gains	1	3
Gross Unrealized Losses	(17)	(1)
Total Fair Market Value	34,173	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	10,395	9,995
Gross Unrealized Gains		1
Gross Unrealized Losses	(16)
Total Fair Market Value	10,379	9,996
Short-term Investments \| Obligations of states and municipalities \| Fair Value, Inputs, Level 2
Investment securities classified as held to maturity
Amortized Cost	8,705	14,816
Gross Unrealized Gains	1	2
Gross Unrealized Losses	(1)	(1)
Total Fair Market Value	8,705	14,817
Short-term Investments \| Bank certificates of deposit \| Fair Value, Inputs, Level 2
Investment securities classified as held to maturity
Amortized Cost	15,089	13,215
Total Fair Market Value	15,089	13,215
Long Term Investments
Investment securities classified as held to maturity
Amortized Cost	25,914	26,691
Gross Unrealized Gains	1
Gross Unrealized Losses	(50)	(51)
Total Fair Market Value	25,865	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	14,968	15,011
Gross Unrealized Gains	1
Gross Unrealized Losses	(50)	(51)
Total Fair Market Value	14,919	14,960
Long Term Investments \| Bank certificates of deposit \| Fair Value, Inputs, Level 2
Investment securities classified as held to maturity
Amortized Cost	10,946	11,680
Total Fair Market Value	$ 10,946	$ 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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