Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 29,045	$ 29,461	$ 39,460	$ 71,412
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) on investments	(51)	9	(11)	(14)
Other comprehensive income (loss), net of tax	(51)	9	(11)	(14)
Comprehensive income	$ 28,994	$ 29,470	$ 39,449	$ 71,398

This item represents the pretax change in net unrealized holding gain (loss) on available-for-sale securities that has been included in accumulated other comprehensive income, a separate component of shareholders' equity, during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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