Debt instrument floor interest rate.

No definition available.

Name:	srna_DebtInstrumentFloorInterestRate
Namespace Prefix:	srna_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument floor interest rate description.

+ References

No definition available.

+ Details

Name:	srna_DebtInstrumentFloorInterestRateDescription
Namespace Prefix:	srna_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument negotiated transactions number.

+ References

No definition available.

+ Details

Name:	srna_DebtInstrumentNegotiatedTransactionsNumber
Namespace Prefix:	srna_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srna_DebtTextualAbstract
Namespace Prefix:	srna_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase in interest rate margin.

+ References

No definition available.

+ Details

Name:	srna_IncreaseInInterestRateMargin
Namespace Prefix:	srna_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Issue discount percentage.

+ References

No definition available.

+ Details

Name:	srna_IssueDiscountPercentage
Namespace Prefix:	srna_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility additional borrowing capacity.

+ References

No definition available.

+ Details

Name:	srna_LineOfCreditFacilityAdditionalBorrowingCapacity
Namespace Prefix:	srna_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit facility maximum borrowing capacity amended.

+ References

No definition available.

+ Details

Name:	srna_LineOfCreditFacilityMaximumBorrowingCapacityAmended
Namespace Prefix:	srna_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Loan amortization rate.

+ References

No definition available.

+ Details

Name:	srna_LoanAmortizationRate
Namespace Prefix:	srna_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum leverage ratio.

+ References

No definition available.

+ Details

Name:	srna_MaximumLeverageRatio
Namespace Prefix:	srna_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Redemption rate at option of holder.

+ References

No definition available.

+ Details

Name:	srna_RedemptionRateAtOptionOfHolder
Namespace Prefix:	srna_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Term loan amortization description.

+ References

No definition available.

+ Details

Name:	srna_TermLoanAmortizationDescription
Namespace Prefix:	srna_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Term loan maturity period.

+ References

No definition available.

+ Details

Name:	srna_TermLoanMaturityPeriod
Namespace Prefix:	srna_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Term loan prior period used for calculation of maturity date.

+ References

No definition available.

+ Details

Name:	srna_TermLoanPriorPeriodUsedForCalculationOfMaturityDate
Namespace Prefix:	srna_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of revolving credit facility.

+ References

No definition available.

+ Details

Name:	srna_TermOfRevolvingCreditFacility
Namespace Prefix:	srna_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the total principal payments made during the annual reporting period.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

Name:	us-gaap_DebtInstrumentAnnualPrincipalPayment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Interest rate stated in the contractual debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

Name:	us-gaap_ExtinguishmentOfDebtAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The difference between the reacquisition price and the net carrying amount of the extinguished debt recognized currently as a component of income in the period of extinguishment, net of tax.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 145

-Paragraph A5

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 26

-Paragraph 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12317-112629

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6401765&loc=d3e13305-112630

+ Details

Name:	us-gaap_ExtinguishmentOfDebtGainLossNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Decrease for amounts repaid on the credit facility for the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(f))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph f

-Article 4

+ Details

Name:	us-gaap_LineOfCreditFacilityDecreaseRepayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ 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 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13476-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Debt (Details Textual) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended				3 Months Ended					1 Months Ended		3 Months Ended	12 Months Ended		3 Months Ended					1 Months Ended	3 Months Ended		3 Months Ended	1 Months Ended
	Feb. 28, 2011	Apr. 30, 2013 Negotiated_Transactions	Apr. 12, 2012	Jan. 31, 2011	Jan. 31, 2010	Apr. 30, 2013 Revolving Credit Facility [Member]	Apr. 30, 2013 Non Extended 2012 Revolving Credit Facility [Member]	Oct. 31, 2011 Non Extended 2012 Revolving Credit Facility [Member]	Apr. 30, 2013 Extended 2015 Revolving Credit Facility [Member]	Mar. 02, 2011 Extended 2015 Revolving Credit Facility [Member]	Apr. 30, 2012 Tranche B Term Loans [Member]	Apr. 30, 2013 Tranche B Term Loans [Member]	Apr. 30, 2013 Senior Subordinated Notes [Member]	Jan. 31, 2011 Senior Subordinated Notes [Member]	Jan. 31, 2010 Senior Subordinated Notes [Member]	Apr. 30, 2013 Senior Secured Credit Agreement [Member]	Jan. 31, 2013 Senior Secured Credit Agreement [Member]	Apr. 30, 2013 Extended Term Loans [Member]	Apr. 12, 2012 Extended Term Loans [Member]	Mar. 02, 2011 Extended Term Loans [Member]	Apr. 30, 2012 2016 Tranche B Term Loan [Member]	Apr. 30, 2013 Non Extended Term Loans [Member]	Mar. 02, 2011 Non Extended Term Loans [Member]	Apr. 30, 2013 Term Loans [Member]	Apr. 30, 2012 Amendment One [Member] 2016 Tranche B Term Loan [Member]	Apr. 12, 2012 Amendment One [Member] 2016 Tranche B Term Loan [Member]
Debt (Textual) [Abstract]
Maximum borrowing capacity						$ 75.0																		$ 400.0
Loan Amortization Rate																1.00%	1.00%
Additional borrowing credit facility						150.0
Term loan amortization description		Amortizing at a rate of 1.00% per year on a quarterly basis for the first six and three-quarters years with the balance paid at maturity
Term of revolving credit facility						6 years
Period of term Loan																								7 years
Amount outstanding							55.0			20.0			101.5						117.4	191.1			124.9
Term Loan maturity date							Mar. 10, 2012						Mar. 15, 2016					Mar. 10, 2016				Mar. 10, 2013
Debt Instrument, Maturity Date		Mar. 10, 2016							Mar. 10, 2015				Mar. 15, 2016
Term loan expiration prior to number of days		180 days
Maximum revolving credit facility, after amendment							20.0
Debt Instrument, Description of Variable Rate Basis																									London Interbank Offered Rate, or LIBOR, based loans of 4.0%
Debt instrument annual rate												5.00%	10.375%					4.20%								4.00%
Amount repaid			84.4
Increase In Interest Rate Margin									2.00%
Leverage Ratio											0.0425
Issue Discount Percentage																					1.50%
Redemption Rate at Option of Holder													101.00%
Cancellation of the non-extended 2012 revolving credit commitment								55.0
Senior Subordinated Notes Face value				200.0	200.0
Percentage of interest floor basis spread on term loan																									LIBOR floor of 1.0%.
Percentage of interest floor on term loan, fixed																									1.00%
Number of negotiation transactions		2
Repurchased amount													32.7	8.7	57.0
Gain (Loss) on Extinguishment of Debt													$ 1.0	$ 0.2
Commitment fees payable, percentage	0.375%