For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Benefit Obligation

-URI http://asc.fasb.org/extlink&oid=6503844

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

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- Definition

Disclosure of how the assumed discount rate was determined and the specific source data used to support the discount rate.

+ References

No definition available.

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- Definition

Expected rate of compensation increases (for pay-related plans).

+ References

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ References

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- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

+ References

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- Definition

Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ 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 (d)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

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- Definition

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

+ References

No definition available.

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- Definition

Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan.

+ References

No definition available.

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- Definition

Additional participant contribution percentage on an after tax basis of eligible base pay.

+ References

No definition available.

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Data Type:	num:percentItemType
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- Definition

Maximum participant contribution to invest in company stock.

+ References

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Data Type:	num:percentItemType
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- Definition

Participants investment in company stock feature elimination date.

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Data Type:	xbrli:dateItemType
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- Definition

Total retirement, post-retirement benefit plan and defined benefit plan expense for the fiscal year.

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No definition available.

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Retirement Plans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 26, 2014	Sep. 27, 2013	Sep. 28, 2012
Retirement Plans [Line Items]
Eligible participants investment in company stock feature elimination date	Jan. 01, 2015
Total retirement, post-retirement benefit plan and defined benefit plan expense	$ 28.6	$ 29.0	$ 27.9
Accumulated benefit obligation for defined benefit pension plans	172.7	167.3
Equity Securities
Retirement Plans [Line Items]
Target percentage allocation	33.00%
Debt and fixed income assets
Retirement Plans [Line Items]
Target percentage allocation	56.00%
Other
Retirement Plans [Line Items]
Target percentage allocation	11.00%
US 401(K) Plan
Retirement Plans [Line Items]
Maximum eligible participant compensation that company matches under defined contribution plan	6.00%
Maximum participant contribution allowed to be invested in VMS common stock	25.00%
US 401(K) Plan \| Minimum
Retirement Plans [Line Items]
Participant contribution for eligible base compensation	1.00%
US 401(K) Plan \| Maximum
Retirement Plans [Line Items]
Participant contribution for eligible base compensation	25.00%
Contribution as percentage on after-tax basis	15.00%
U.K. Savings Plan
Retirement Plans [Line Items]
Maximum eligible participant compensation that company matches under defined contribution plan	6.00%
U.K. Savings Plan \| Minimum
Retirement Plans [Line Items]
Participant contribution for eligible base compensation	4.00%
U.K. Savings Plan \| Maximum
Retirement Plans [Line Items]
Participant contribution for eligible base compensation	100.00%
Defined Benefit Plans
Retirement Plans [Line Items]
Discount rate	2.77%	3.11%
Rate of projected compensation increase	2.45%	2.51%
Discount rates used to determine the benefit obligations - methodology	For defined benefit pension plans, the discount rate was adjusted as of September 26, 2014 to a range of 1.30% to 4.00%, primarily based on the current effective yield of long-term corporate bonds that are of high quality with satisfactory liquidity and credit rating with durations corresponding to the expected duration of the benefit obligations.
Contributions by employer	7.2	22.2
Expected total contribution to the defined benefit plans for the fiscal year 2015	7.3
Defined Benefit Plans \| Minimum
Retirement Plans [Line Items]
Discount rate	1.30%
Rate of projected compensation increase	1.75%
Defined Benefit Plans \| Maximum
Retirement Plans [Line Items]
Discount rate	4.00%
Rate of projected compensation increase	3.70%
Post-Retirement Benefit Plans
Retirement Plans [Line Items]
Discount rate	3.10%	3.80%
Discount rates used to determine the benefit obligations - methodology	Based on the yields of high quality zero-coupon corporate bonds with maturities that match the expected durations of the benefit obligations
Contributions by employer	0.5	0.5
Expected total contribution to the defined benefit plans for the fiscal year 2015	$ 0.3