RETIREMENT PLANS: - Qualified 401(k) and SNQDC Plans (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Qualified 401(k) and SNQDC Plans
Matching contribution of first 6% of employees' annual aggregate contributions (as a percent )	50.00%
Percentage of employees' contributions matched by the company	6.00%
Contributions to qualified 401(k) and SNQDC plans	$ 6,500	$ 6,100	$ 5,300
Assets of the SNQDC Plan included in other current assets	12,716	12,532
SNQDC Plan
Qualified 401(k) and SNQDC Plans
Assets of the SNQDC Plan included in other current assets	12,700	12,500
Liabilities of the SNQDC Plan included in other accrued liabilities	$ 12,700	$ 12,500

Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements payable within one year (or the normal operating cycle, if longer). Represents currently earned compensation under cash arrangements (such as a profit-sharing plan, rabbi trust, and employee contract--excluding equity-based arrangements) that is not actually paid until a later date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 30
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20028-108363

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 710
-SubTopic 10
-Section 25
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=6409836&loc=d3e19793-108362

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- Definition

For a classified balance sheet, the amount recognized in balance sheet as a current asset associated with the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919

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- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

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