defined Benefit Plan Employer Discretionary Contributions

Name:	cnw_DefinedBenefitPlanEmployerDiscretionaryContributions
Namespace Prefix:	cnw
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Defined Contribution Plan Accrued Liabilities

+ Details

Name:	cnw_DefinedContributionPlanAccruedLiabilities
Namespace Prefix:	cnw
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Defined Contribution Plan Limited Basic Contributions

+ Details

Name:	cnw_DefinedContributionPlanLimitedBasicContributions
Namespace Prefix:	cnw
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Contribution Plan Limited Transition Contributions

+ Details

Name:	cnw_DefinedContributionPlanLimitedTransitionContributions
Namespace Prefix:	cnw
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase Decrease Compensated Absences Benefit

+ Details

Name:	cnw_IncreaseDecreaseCompensatedAbsencesBenefit
Namespace Prefix:	cnw
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase Decrease In Salaries And Wages

+ Details

Name:	cnw_IncreaseDecreaseInSalariesAndWages
Namespace Prefix:	cnw
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Repurchased common stock issued under defined contribution plan

+ Details

Name:	cnw_RepurchasedCommonStockIssuedUnderDefinedContributionPlan
Namespace Prefix:	cnw
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan in the current remaining fiscal period. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

+ Details

Name:	us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInCurrentFiscalYear
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of the cost recognized during the period for defined contribution plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 11
-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 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942

+ Details

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

For a classified balance sheet, the amount recognized in balance sheet as a current liability associated with an underfunded defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6410544&loc=d3e1703-114919

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph c
-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 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 3
-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 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Current Liabilities
-URI http://asc.fasb.org/extlink&oid=6509677

+ Details

Name:	us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This represents the noncurrent liability for underfunded plans recognized in the balance sheet that is associated with the defined benefit pension plans and other postretirement defined benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2410-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 6
-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 Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 3
-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 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph c
-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 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2417-114920

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6410544&loc=d3e1703-114919

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.24)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

+ Details

Name:	us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Employee Benefit Plans (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended	6 Months Ended			6 Months Ended				3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended
Employee Benefit Plans (Narrative) (Details) (USD $)	Apr. 30, 2009	Mar. 31, 2009	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2011 Maximum [Member]	Jun. 30, 2011 Minimum [Member]	Jul. 31, 2011 Qualified Pension Plans [Member]	Jun. 30, 2011 Qualified Pension Plans [Member]	Jun. 30, 2011 Long-Term Disability Plan [Member]	Jun. 30, 2010 Long-Term Disability Plan [Member]	Jun. 30, 2011 Long-Term Disability Plan [Member]	Jun. 30, 2010 Long-Term Disability Plan [Member]	Dec. 31, 2010 Long-Term Disability Plan [Member]	Jun. 30, 2011 Defined Contribution Retirement Plans [Member]	Jun. 30, 2010 Defined Contribution Retirement Plans [Member]	Jun. 30, 2011 Defined Contribution Retirement Plans [Member]	Jun. 30, 2010 Defined Contribution Retirement Plans [Member]	Dec. 31, 2010 Defined Contribution Retirement Plans [Member]
Required contributions									$ 22,000,000
Discretionary contributions								9,700,000	40,600,000
Defined benefit plan expense										3,700,000	4,000,000	6,300,000	7,100,000		8,800,000	10,300,000	17,700,000	19,200,000
Recognized accrued liabilities															10,800,000		10,800,000		10,400,000
Repurchased common stock issued under defined contribution plan			17,307,000	17,945,000													461,151	511,319
Defined benefit plan employer contribution																	17,300,000	17,900,000
Long-term portion of the obligation			401,944,000		418,731,000					21,800,000		21,800,000		22,100,000
Current portion of the obligation										$ 11,400,000		$ 11,400,000		$ 11,400,000
Percentage of reduction in salaries and wages		5.00%
Reduction in compensated-absences benefit		25.00%
Limited basic contribution in percentage	3.00%					5.00%	3.00%
Limited transition contribution in percentage						3.00%	1.00%