Fair Value Measurements - Liabilities and Assets Measured at Fair Value (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Other assets \| Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-COLI assets held in Deferred Supplemental Compensation Plan	$ 389	$ 299
Other current assets \| Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swaps	$ 294	$ 73

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This element represents the fair value of mutual funds held in DSC plan.

No definition available.

Name:	vsec_MutualFundsHeldInDscPlanFairValueDisclosure
Namespace Prefix:	vsec_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant