Treasury Stock - Summary of Share Repurchases and Cumulatively Since Inception of Authorization (Detail) (USD $)	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Equity [Abstract]
Shares repurchased	845,014us-gaap_TreasuryStockSharesAcquired	830,460us-gaap_TreasuryStockSharesAcquired	1,410,812us-gaap_TreasuryStockSharesAcquired
Cost	$ 31,798,000	$ 27,179,000	$ 30,727,000
Average price	$ 37.63	$ 32.73	$ 21.78
Shares repurchased, Cumulative	32,992,488us-gaap_TreasuryStockShares	32,147,474us-gaap_TreasuryStockShares
Cost, Cumulative	$ 360,278,000us-gaap_TreasuryStockValue	$ 328,480,000us-gaap_TreasuryStockValue
Average price, Cumulative	$ 10.92crvl_TreasuryStockAverageCostPerShare

Treasury Stock Average Cost Per Share

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- Definition

Total cost of shares repurchased divided by the total number of shares repurchased.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

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- Definition

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28,29)

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Number of shares that have been repurchased during the period and are being held in treasury.

+ References

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- Definition

The amount allocated to treasury stock. Treasury stock is common and preferred shares of an entity that were issued, repurchased by the entity, and are held in its treasury.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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-Topic 505

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- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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-Topic 505

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