Employee Benefits - Assumptions Used In Determining Benefit Obligations (Details)	Dec. 31, 2013	Dec. 31, 2012
Pension Plans
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.77%	3.65%
Rate of compensation increase	3.50%	0.00%
Health Care and Life
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	5.01%
Rate of compensation increase	3.50%
Initial trend rate pre-Medicare	8.00%
Initial trend rate Medicare	7.50%
Ultimate trend rate	5.00%

Represents the initial trend rate used to calculate benefit obligation, pre-Medicare.

No definition available.

Name:	dxm_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationInitialTrendRatePreMedicare
Namespace Prefix:	dxm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the ultimate trend rate used to calculate benefit obligation for Medicare.

+ References

No definition available.

+ Details

Name:	dxm_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationUltimateTrendRateMedicare
Namespace Prefix:	dxm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the medicare initial trend rate used to calculate benefit obligation.

+ References

No definition available.

+ Details

Name:	dxm_DefinedBenefitPlanAssumptionsUsedInCalculatingBenefitObligationInitialTrendRateMedicare
Namespace Prefix:	dxm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ 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 (k)(1)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

+ Details

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

- Definition

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

+ 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 (k)(2)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

+ Details

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

- Details

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