Finite-Lived and Indefinite-Lived Intangible Assets

No definition available.

Name:	dy_FiniteLivedAndIndefiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	dy_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

+ Details

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

- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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

- Definition

Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount before accumulated amortization of intangible assets, excluding goodwill.

+ References

No definition available.

+ Details

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

- Definition

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph ((a)(1),(b))
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274

+ Details

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

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=dy_UtiliquestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TradeNamesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_NoncompeteAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 27, 2018	Oct. 28, 2017	Oct. 27, 2018	Oct. 28, 2017	Jan. 27, 2018
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 5,800	$ 6,300	$ 17,200	$ 18,800
Intangible Assets, Gross (Excluding Goodwill)	327,267		327,267		$ 315,217
Accumulated Amortization	160,717		160,717		143,748
Intangible Assets, Net	166,550		166,550		171,469
UtiliQuest
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	4,700		4,700		4,700
Accumulated Amortization	0		0		0
Intangible Assets, Net	$ 4,700		4,700		4,700
Customer relationships
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Usesul life	11 years 3 months
Intangible Assets, Gross (Excluding Goodwill)	$ 312,017		312,017		299,717
Accumulated Amortization	152,380		152,380		135,544
Intangible Assets, Net	$ 159,637		159,637		164,173
Trade names
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Usesul life	8 years 1 month
Intangible Assets, Gross (Excluding Goodwill)	$ 10,350		10,350		10,350
Accumulated Amortization	8,208		8,208		7,872
Intangible Assets, Net	$ 2,142		2,142		2,478
Non-compete agreements
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Usesul life	1 year 9 months
Intangible Assets, Gross (Excluding Goodwill)	$ 200		200		450
Accumulated Amortization	129		129		332
Intangible Assets, Net	$ 71		$ 71		$ 118