Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2017	Aug. 31, 2016
Statement of Comprehensive Income [Abstract]
Change in net unrealized gains (losses), tax effect	$ 0	$ 0	$ 0	$ 0
Reclassification adjustment for net gains (losses) included in net income, tax effect	$ 4	$ (247)	$ 6	$ (394)

Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e640-108580

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