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PENSION AND POSTRETIREMENT PLANS (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Defined Benefit Plans Disclosures [Line Items]      
Maximum deferral percentage of annual base salary 50.00%lh_Maximumdeferralpercentageofannualbasesalary    
Defined Benefit Plan, Funded Status of Plan $ 119.6us-gaap_DefinedBenefitPlanFundedStatusOfPlan $ 81.6us-gaap_DefinedBenefitPlanFundedStatusOfPlan  
Minimum non-elective contribution (NEC) % for the 401(K) plan (in hundredths) 3.00%lh_NonElectiveContribution    
Discretionary contribution % for the 401(K) plan, range minimum (in hundredths) 1.00%lh_DiscretionaryContributionPercentageMinimum    
Discretionary contribution % for the 401(K) plan, range maximum (in hundredths) 3.00%lh_DiscretionaryContributionPercentageMaximum    
Defined contribution retirement plan cost 51.6us-gaap_DefinedContributionPlanCostRecognized 49.4us-gaap_DefinedContributionPlanCostRecognized 49.0us-gaap_DefinedContributionPlanCostRecognized
Company contributions to the defined benefit retirement plan 12.4us-gaap_PensionContributions 8.4us-gaap_PensionContributions 11.3us-gaap_PensionContributions
Defined Benefit Plans, Changes in Fair Value of Plan Assets [Roll Forward]      
Fair value of plan assets at beginning of year 268.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets    
Fair value of plan assets at end of year 269.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets 268.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets  
Defined Benefit Plans, Assets, Target Allocations [Abstract]      
Pension and Other Postretirement Benefits Disclosure [Text Block]
PENSION AND POSTRETIREMENT PLANS

Pension Plans

The Company has a defined benefit retirement plan (the "Company Plan") and a nonqualified supplemental retirement plan (the “PEP”). Both plans have been closed to new participants since December 31, 2009. Employees participating in the Company Plan and the PEP no longer earn service-based credits, but continue to earn interest credits. In addition, effective January 1, 2010, all employees eligible for the defined contribution retirement plan (the “401K Plan”) receive a minimum 3% non-elective contribution (“NEC”) concurrent with each payroll period. Employees are not required to make a contribution to the 401K Plan to receive the NEC. The NEC is non-forfeitable and vests immediately. The 401K Plan also permits discretionary contributions by the Company of up to 1% and up to 3% of pay for eligible employees based on service.

The Company’s 401K Plan covers substantially all employees. Prior to 2010, Company contributions to the plan were based on a percentage of employee contributions. In 2013, 2012 and 2011, the Company made non-elective and discretionary contributions to the plan. Non-elective and discretionary contributions were $51.6, $49.4 and $49.0 in 2014, 2013 and 2012, respectively.

In addition, the Company Plan covers substantially all employees hired prior to December 31, 2009. The benefits to be paid under the Company Plan are based on years of credited service through December 31, 2009, interest credits and average compensation. The Company’s policy is to fund the Company Plan with at least the minimum amount required by applicable regulations. The Company made contributions to the Company Plan of $12.4, $8.4 and $11.3 in 2014, 2013 and 2012, respectively.

The PEP covers the Company’s senior management group. Prior to 2010, the PEP provided for the payment of the difference, if any, between the amount of any maximum limitation on annual benefit payments under the Employee Retirement Income Security Act of 1974 and the annual benefit that would be payable under the Company Plan but for such limitation. Effective January 1, 2010, employees participating in the PEP no longer earn service-based credits. The PEP is an unfunded plan.

Projected pension expense for the Company Plan and the PEP is expected to increase to $11.6 in 2015. This amount excludes any accelerated recognition of pension cost due to the total lump-sum payouts exceeding certain components of net periodic pension cost in a fiscal year.  If such levels were to be met in 2015, the Company projects that it would result in additional pension expense of several million dollars. The actual amount would be determined in the fiscal quarter when the lump-sum payments cross the threshold and would be based upon the plan's funded status and actuarial assumptions in effect at that time.   

The Company plans to make contributions of $11.1 to the Company Plan during 2015.
 
The effect on operations for both the Company Plan and the PEP are summarized as follows:

 
Year ended December 31,
 
2014
 
2013
 
2012
Service cost for benefits earned
$
3.4

 
$
3.1

 
$
2.4

Interest cost on benefit obligation
16.4

 
14.7

 
14.9

Expected return on plan assets
(18.3
)
 
(17.3
)
 
(17.3
)
Net amortization and deferral
6.6

 
10.5

 
12.1

Defined benefit plan costs
$
8.1

 
$
11.0

 
$
12.1



Amounts included in accumulated other comprehensive earnings consist of unamortized net loss of $142.2. The accumulated other comprehensive earnings that are expected to be recognized as components of the defined benefit plan costs during 2015 are $11.1 related to amortization of the net loss.

A summary of the changes in the projected benefit obligations of the Company Plan and the PEP are summarized as follows:

 
2014
 
2013
Balance at January 1
$
349.7

 
$
380.7

Service cost
3.4

 
3.1

Interest cost
16.4

 
14.7

Actuarial (gain)/loss
47.1

 
(22.1
)
Benefits and administrative expenses paid
(28.0
)
 
(26.7
)
Balance at December 31
$
388.6

 
$
349.7



The Accumulated Benefit Obligation was $388.6 and $349.7 at December 31, 2014 and 2013, respectively.



A summary of the changes in the fair value of plan assets follows:
 
2014
 
2013
Fair value of plan assets at beginning of year
$
268.1

 
$
256.8

Actual return on plan assets
15.2

 
28.1

Employer contributions
13.8

 
9.9

Benefits and administrative expenses paid
(28.0
)
 
(26.7
)
Fair value of plan assets at end of year
$
269.1

 
$
268.1



The net funded status of the Company Plan and the PEP at December 31:

Funded status
$
119.6

 
$
81.6

 
 
 
 
Recorded as:
 
 
 
Accrued expenses and other
$
1.7

 
$
1.6

Other liabilities
117.9

 
80.0

 
$
119.6

 
$
81.6



Weighted average assumptions used in the accounting for the Company Plan and the PEP are summarized as follows:

 
2014
 
2013
 
2012
Discount rate
4.0
%
 
4.8
%
 
4.0
%
Expected long term rate of return
7.0
%
 
7.0
%
 
7.0
%


The Company also updated the mortality assumption to the RP-2014 Mortality Tables in 2014 which increased the Company's total projected obligation.

The Company maintains an investment policy for the management of the Company Plan’s assets. The objective of this policy is to build a portfolio designed to achieve a balance between investment return and asset protection by investing in indexed funds that are comprised of equities of high quality companies and in high quality fixed income securities which are broadly balanced and represent all market sectors. The target allocations for plan assets are 50% equity securities, 45% fixed income securities and 5% in other assets. Equity securities primarily include investments in large-cap, mid-cap and small-cap companies located in the U.S. and to a lesser extent international equities in developed and emerging countries. Fixed income securities primarily include U.S. Treasury securities, mortgage-backed bonds and corporate bonds of companies from diversified industries. Other assets include investments in commodities. The weighted average expected long-term rate of return for the Company Plan’s assets is as follows:

 
Target
Allocation
 
Weighted
Average
Expected
Long-Term
Rate
of Return
Equity securities
50.0
%
 
3.5
%
Fixed income securities
45.0
%
 
1.2
%
Other assets
5.0
%
 
0.3
%


The fair values of the Company Plan’s assets at December 31, 2014 and 2013, by asset category are as follows:
 
 
 
Fair Value Measurements as of
 
 
 
December 31, 2014
 
Fair Value as of December 31, 2014
 
Using Fair Value Hierarchy
Asset Category
 
Level 1
 
Level 2
 
Level 3
Cash
$
4.1

 
$
4.1

 
$

 
$

Equity securities:
 

 
 

 
 

 
 

U.S. large cap - blend (a)
64.1

 

 
64.1

 

U.S. mid cap - blend (b)
25.3

 

 
25.3

 

U.S. small cap - blend (c)
7.9

 

 
7.9

 

International equity - blend (d)
36.0

 

 
36.0

 

Commodities index (e)
10.3

 

 
10.3

 

Fixed income securities:
 

 
 

 
 

 
 

U.S. fixed income (f)
115.1

 

 
115.1

 

U.S inflation protection income (g)
6.3

 

 
6.3

 

Total fair value of the Company Plan’s assets
$
269.1

 
$
4.1

 
$
265.0

 
$


 
 
 
Fair Value Measurements as of
 
 
 
December 31, 2013
 
Fair Value as of December 31, 2013
 
Using Fair Value Hierarchy
Asset Category
 
Level 1
 
Level 2
 
Level 3
Cash
$
2.7

 
$
2.7

 
$

 
$

Equity securities:
 

 
 

 
 

 
 

U.S. large cap - blend (a)
65.5

 

 
65.5

 

U.S. mid cap - blend (b)
25.1

 

 
25.1

 

U.S. small cap - blend (c)
8.1

 

 
8.1

 

International equity - blend (d)
40.3

 

 
40.3

 

Commodities index (e)
11.3

 

 
11.3

 

Fixed income securities:
 

 
 

 
 

 
 

U.S. fixed income (f)
104.1

 

 
104.1

 

U.S inflation protection income (g)
11.0

 
 
 
11.0

 
 
Total fair value of the Company Plan’s assets
$
268.1

 
$
2.7

 
$
265.4

 
$


a)
This category represents an equity index fund not actively managed that tracks the S&P 500 Index.
b)
This category represents an equity index fund not actively managed that tracks the S&P mid-cap 400 Index.
c)
This category represents an equity index fund not actively managed that tracks the Russell 2000 Index.
d)
This category represents an equity index fund not actively managed that tracks the MSCI ACWI ex USA Index.
e)
This category represents a commodities index fund not actively managed that tracks the Dow Jones - UBS Commodity Index.
f)
This category primarily represents bond index funds not actively managed that track the Barclays Capital U.S. Aggregate Index and Barclays Capital U.S. TIPS Index.
g)
This category primarily represents a bond index fund not actively managed that tracks the Barclays Capital U.S. TIPS Index.



The following assumed benefit payments under the Company Plan and PEP, which were used in the calculation of projected benefit obligations, are expected to be paid as follows:

2014
$
25.9

2015
25.4

2016
24.8

2017
24.6

2018
24.9

Years 2019-2023
123.9



Post-retirement Medical Plan

The Company assumed obligations under a subsidiary's post-retirement medical plan. Coverage under this plan is restricted to a limited number of existing employees of the subsidiary. This plan is unfunded and the Company’s policy is to fund benefits as claims are incurred. The effect on operations of the post-retirement medical plan is shown in the following table:

 
Year ended December 31,
 
2014
 
2013
 
2012
Service cost for benefits earned
$
0.2

 
$
0.4

 
$
0.4

Interest cost on benefit obligation
1.8

 
2.5

 
2.3

Net amortization and deferral
(7.9
)
 
1.0

 
0.3

Post-retirement medical plan costs
$
(5.9
)
 
$
3.9

 
$
3.0



Amounts included in accumulated other comprehensive earnings consist of unamortized net loss of $12.9. The accumulated other comprehensive earnings that are expected to be recognized as components of the post-retirement medical plan costs during 2015 are $9.3 related to amortization of the net gain resulting from the shift of Medicare-eligible participants to private exchanges.

A summary of the changes in the accumulated post-retirement benefit obligation follows:

 
2014
 
2013
Balance at January 1
$
62.7

 
$
60.7

Service cost for benefits earned
0.2

 
0.4

Interest cost on benefit obligation
1.8

 
2.5

Participants contributions
0.2

 
0.3

Actuarial loss
(7.2
)
 
4.5

Benefits paid
(2.5
)
 
(2.7
)
Plan amendment
(26.3
)
 
(3.0
)
Balance at December 31
$
28.9

 
$
62.7

 
 
 
 
Recorded as:
 
 
 
   Accrued expenses and other
$
2.2

 
$

   Other liabilities
26.7

 
62.7

 
$
28.9

 
$
62.7


 
The weighted-average discount rates used in the calculation of the accumulated post-retirement benefit obligation were 4.0% and 5.0% as of December 31, 2014 and 2013, respectively. The health care cost trend rate was assumed to be 7.0% of December 31, 2014 and 2013, declining gradually to 5.0% in the year 2021. The health care cost trend rate has a significant effect on the amounts reported. The impact of a percentage point change each year in the assumed health care cost trend rates would change the accumulated post-retirement benefit obligation as of December 31, 2014 by an increase of $0.5 or a decrease of $0.5. The impact of a percentage point change on the aggregate of the service cost and interest cost components of the 2014 post-retirement benefit costs results in an increase of $0.3 or decrease of $0.2. The plan amendment in 2014 reflects the shift of Medicare-eligible participants to private exchanges and updating the mortality assumption to the RP-2014 Mortality Tables. The plan amendment in 2013 reflects the impact of shifting from projection scale AA to projection scale BB for both the RP-2000 Combined Healthy Mortality Table and the RP-2000 Disabled Mortality Table.

The following assumed benefit payments under the Company's post-retirement benefit plan, which reflect expected future service, as appropriate, and were used in the calculation of projected benefit obligations, are expected to be paid as follows:

2015
$
2.3

2016
2.3

2017
2.2

2018
2.2

2019
2.2

Years 2020-2024
10.3


Deferred Compensation Plan

In 2001, the Board approved the Deferred Compensation Plan ("DCP") under which certain of the Company's executives, may elect to defer up to 100.0% of their annual cash incentive pay and/or up to 50.0% of their annual base salary and/or eligible commissions subject to annual limits established by the federal government. The DCP provides executives a tax efficient strategy for retirement savings and capital accumulation without significant cost to the Company. The Company makes no contributions to the DCP. Amounts deferred by a participant are credited to a bookkeeping account maintained on behalf of each participant, which is used for measurement and determination of amounts to be paid to a participant, or his or her designated beneficiary, pursuant to the terms of the DCP. The amounts accrued under this plan were $43.4 and $36.3 at December 31, 2014 and 2013, respectively. Deferred amounts are the Company's general unsecured obligations and are subject to claims by the Company's creditors. The Company's general assets may be used to fund obligations and pay DCP benefits.
   
Schedule Of Pension and Postretirement Plans
The effect on operations for both the Company Plan and the PEP are summarized as follows:

 
Year ended December 31,
 
2014
 
2013
 
2012
Service cost for benefits earned
$
3.4

 
$
3.1

 
$
2.4

Interest cost on benefit obligation
16.4

 
14.7

 
14.9

Expected return on plan assets
(18.3
)
 
(17.3
)
 
(17.3
)
Net amortization and deferral
6.6

 
10.5

 
12.1

Defined benefit plan costs
$
8.1

 
$
11.0

 
$
12.1

A summary of the changes in the projected benefit obligations of the Company Plan and the PEP are summarized as follows:

 
2014
 
2013
Balance at January 1
$
349.7

 
$
380.7

Service cost
3.4

 
3.1

Interest cost
16.4

 
14.7

Actuarial (gain)/loss
47.1

 
(22.1
)
Benefits and administrative expenses paid
(28.0
)
 
(26.7
)
Balance at December 31
$
388.6

 
$
349.7

 
Year ended December 31,
 
2014
 
2013
 
2012
Service cost for benefits earned
$
0.2

 
$
0.4

 
$
0.4

Interest cost on benefit obligation
1.8

 
2.5

 
2.3

Net amortization and deferral
(7.9
)
 
1.0

 
0.3

Post-retirement medical plan costs
$
(5.9
)
 
$
3.9

 
$
3.0

A summary of the changes in the accumulated post-retirement benefit obligation follows:

 
2014
 
2013
Balance at January 1
$
62.7

 
$
60.7

Service cost for benefits earned
0.2

 
0.4

Interest cost on benefit obligation
1.8

 
2.5

Participants contributions
0.2

 
0.3

Actuarial loss
(7.2
)
 
4.5

Benefits paid
(2.5
)
 
(2.7
)
Plan amendment
(26.3
)
 
(3.0
)
Balance at December 31
$
28.9

 
$
62.7

 
 
 
 
Recorded as:
 
 
 
   Accrued expenses and other
$
2.2

 
$

   Other liabilities
26.7

 
62.7

 
$
28.9

 
$
62.7

   
Schedule of Changes in Fair Value of Plan Assets
A summary of the changes in the fair value of plan assets follows:
 
2014
 
2013
Fair value of plan assets at beginning of year
$
268.1

 
$
256.8

Actual return on plan assets
15.2

 
28.1

Employer contributions
13.8

 
9.9

Benefits and administrative expenses paid
(28.0
)
 
(26.7
)
Fair value of plan assets at end of year
$
269.1

 
$
268.1

   
Schedule of Net Funded Status
The net funded status of the Company Plan and the PEP at December 31:

Funded status
$
119.6

 
$
81.6

 
 
 
 
Recorded as:
 
 
 
Accrued expenses and other
$
1.7

 
$
1.6

Other liabilities
117.9

 
80.0

 
$
119.6

 
$
81.6

   
Schedule of Assumptions Used
Weighted average assumptions used in the accounting for the Company Plan and the PEP are summarized as follows:

 
2014
 
2013
 
2012
Discount rate
4.0
%
 
4.8
%
 
4.0
%
Expected long term rate of return
7.0
%
 
7.0
%
 
7.0
%
   
Plan Assets at Fair Value By Asset Category
The weighted average expected long-term rate of return for the Company Plan’s assets is as follows:

 
Target
Allocation
 
Weighted
Average
Expected
Long-Term
Rate
of Return
Equity securities
50.0
%
 
3.5
%
Fixed income securities
45.0
%
 
1.2
%
Other assets
5.0
%
 
0.3
%


The fair values of the Company Plan’s assets at December 31, 2014 and 2013, by asset category are as follows:
 
 
 
Fair Value Measurements as of
 
 
 
December 31, 2014
 
Fair Value as of December 31, 2014
 
Using Fair Value Hierarchy
Asset Category
 
Level 1
 
Level 2
 
Level 3
Cash
$
4.1

 
$
4.1

 
$

 
$

Equity securities:
 

 
 

 
 

 
 

U.S. large cap - blend (a)
64.1

 

 
64.1

 

U.S. mid cap - blend (b)
25.3

 

 
25.3

 

U.S. small cap - blend (c)
7.9

 

 
7.9

 

International equity - blend (d)
36.0

 

 
36.0

 

Commodities index (e)
10.3

 

 
10.3

 

Fixed income securities:
 

 
 

 
 

 
 

U.S. fixed income (f)
115.1

 

 
115.1

 

U.S inflation protection income (g)
6.3

 

 
6.3

 

Total fair value of the Company Plan’s assets
$
269.1

 
$
4.1

 
$
265.0

 
$


 
 
 
Fair Value Measurements as of
 
 
 
December 31, 2013
 
Fair Value as of December 31, 2013
 
Using Fair Value Hierarchy
Asset Category
 
Level 1
 
Level 2
 
Level 3
Cash
$
2.7

 
$
2.7

 
$

 
$

Equity securities:
 

 
 

 
 

 
 

U.S. large cap - blend (a)
65.5

 

 
65.5

 

U.S. mid cap - blend (b)
25.1

 

 
25.1

 

U.S. small cap - blend (c)
8.1

 

 
8.1

 

International equity - blend (d)
40.3

 

 
40.3

 

Commodities index (e)
11.3

 

 
11.3

 

Fixed income securities:
 

 
 

 
 

 
 

U.S. fixed income (f)
104.1

 

 
104.1

 

U.S inflation protection income (g)
11.0

 
 
 
11.0

 
 
Total fair value of the Company Plan’s assets
$
268.1

 
$
2.7

 
$
265.4

 
$


a)
This category represents an equity index fund not actively managed that tracks the S&P 500 Index.
b)
This category represents an equity index fund not actively managed that tracks the S&P mid-cap 400 Index.
c)
This category represents an equity index fund not actively managed that tracks the Russell 2000 Index.
d)
This category represents an equity index fund not actively managed that tracks the MSCI ACWI ex USA Index.
e)
This category represents a commodities index fund not actively managed that tracks the Dow Jones - UBS Commodity Index.
f)
This category primarily represents bond index funds not actively managed that track the Barclays Capital U.S. Aggregate Index and Barclays Capital U.S. TIPS Index.
g)
This category primarily represents a bond index fund not actively managed that tracks the Barclays Capital U.S. TIPS Index.



   
Schedule of Expected Benefit Payments
The following assumed benefit payments under the Company Plan and PEP, which were used in the calculation of projected benefit obligations, are expected to be paid as follows:

2014
$
25.9

2015
25.4

2016
24.8

2017
24.6

2018
24.9

Years 2019-2023
123.9

   
Assumed Benefit Payments By Year
The following assumed benefit payments under the Company's post-retirement benefit plan, which reflect expected future service, as appropriate, and were used in the calculation of projected benefit obligations, are expected to be paid as follows:

2015
$
2.3

2016
2.3

2017
2.2

2018
2.2

2019
2.2

Years 2020-2024
10.3


   
Maximum deferral percentage of annual cash incentive pay 100.00%lh_Maximumdeferralpercentageofannualcashincentivepay    
Deferred Compensation Liability, Classified, Noncurrent 43.4us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent 36.3us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent  
Equity Securities [Member]      
Defined Benefit Plans Disclosures [Line Items]      
Defined Benefit Plan, Target Plan Asset Allocations 50.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
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Fixed Income Securities [Member]      
Defined Benefit Plans Disclosures [Line Items]      
Defined Benefit Plan, Target Plan Asset Allocations 45.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
/ us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis
= us-gaap_FixedIncomeSecuritiesMember
   
Other Liabilities [Member]      
Defined Benefit Plans Disclosures [Line Items]      
Defined Benefit Plan, Funded Status of Plan 117.9us-gaap_DefinedBenefitPlanFundedStatusOfPlan
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80.0us-gaap_DefinedBenefitPlanFundedStatusOfPlan
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Accrued Liabilities [Member]      
Defined Benefit Plans Disclosures [Line Items]      
Defined Benefit Plan, Funded Status of Plan 1.7us-gaap_DefinedBenefitPlanFundedStatusOfPlan
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Other Postretirement Benefit Plan [Member]      
Defined Benefit Plans Disclosures [Line Items]      
Defined Benefit Plan, Expected Future Benefit Payments, Year Three 2.2us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
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Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter 10.3us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
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Defined Benefit Plan, Ultimate Health Care Cost Trend Rate 5.00%us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate
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Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate 2021    
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months 2.3us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
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Effect on operations for both the Company Plan and the PEP [Abstract]      
Service cost 0.2us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0.4us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0.4us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Interest cost (1.8)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(2.5)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(2.3)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Net amortization and deferral (7.9)lh_DefinedBenefitPlanAmortizationAndDeferral
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
1.0lh_DefinedBenefitPlanAmortizationAndDeferral
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0.3lh_DefinedBenefitPlanAmortizationAndDeferral
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Defined benefit plan costs (5.9)us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
3.9us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
3.0us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Unamortized net gain included in accumulated other comprehensive earnings 12.9us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
   
Amortization of net loss (gain) in accumulated other comprehensive earnings, which is expected to be recognized as components of defined benefit plan costs during 2012 9.3us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
   
Defined Benefit Plans, Changes in Benefit Obligations [Roll Forward]      
Beginning balance 62.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
60.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
Service cost 0.2us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0.4us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0.4us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Interest cost (1.8)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(2.5)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(2.3)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Participants contributions 0.2us-gaap_DefinedBenefitPlanContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0.3us-gaap_DefinedBenefitPlanContributionsByPlanParticipants
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
Actuarial (gain)/loss (7.2)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
4.5us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
Benefits and administrative expenses paid (2.5)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(2.7)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
Ending balance 28.9us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
62.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
60.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Defined Benefit Plans, Changes in Fair Value of Plan Assets [Roll Forward]      
Benefits and administrative expenses paid (2.5)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
(2.7)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
Defined Benefit Plans, Weighted Average Assumptions Used in Calculating Benefit Obligations [Abstract]      
Discount rate 4.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
  5.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Defined Benefit Plans, Assets, Target Allocations [Abstract]      
Defined Benefit Plan, Expected Future Benefit Payments, Year Four 2.2us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
   
Defined Benefit Plan, Expected Future Benefit Payments, Year Five 2.2us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
   
Other Postretirement Benefit Plan [Member] | Other Liabilities [Member]      
Defined Benefit Plans, Changes in Benefit Obligations [Roll Forward]      
Ending balance 26.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherLiabilitiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
   
Other Postretirement Benefit Plan [Member] | Accrued Liabilities [Member]      
Defined Benefit Plans, Changes in Benefit Obligations [Roll Forward]      
Ending balance 2.2us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_AccruedLiabilitiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
0us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_AccruedLiabilitiesMember
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
 
Pension Plan [Member]      
Defined Benefit Plans Disclosures [Line Items]      
Defined Benefit Plan, Expected Future Benefit Payments, Year Three 24.8us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter 123.9us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months 25.9us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Defined Benefit Plan, Expected Future Benefit Payments, Year Two 25.4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Defined Benefit Plan, Target Plan Asset Allocations 5.00%us-gaap_DefinedBenefitPlanTargetPlanAssetAllocations
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Projected defined benefit plan costs in fiscal 2012 11.6lh_ProjectedDefinedBenefitPlanNetPeriodicBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Projected defined benefit plan contributions in fiscal 2012 11.1us-gaap_DefinedBenefitPlansEstimatedFutureEmployerContributionsInNextFiscalYear
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Effect on operations for both the Company Plan and the PEP [Abstract]      
Service cost 3.4us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
3.1us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
2.4us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Interest cost (16.4)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(14.7)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(14.9)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Expected return on plan assets (18.3)us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(17.3)us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(17.3)us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Net amortization and deferral 6.6lh_DefinedBenefitPlanAmortizationAndDeferral
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
10.5lh_DefinedBenefitPlanAmortizationAndDeferral
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
12.1lh_DefinedBenefitPlanAmortizationAndDeferral
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Defined benefit plan costs 8.1us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
11.0us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
12.1us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Unamortized net gain included in accumulated other comprehensive earnings 142.2us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Amortization of net loss (gain) in accumulated other comprehensive earnings, which is expected to be recognized as components of defined benefit plan costs during 2012 11.1us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Defined Benefit Plans, Changes in Benefit Obligations [Roll Forward]      
Beginning balance 349.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
380.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
Service cost 3.4us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
3.1us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
2.4us-gaap_DefinedBenefitPlanServiceCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Interest cost (16.4)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(14.7)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(14.9)us-gaap_DefinedBenefitPlanInterestCost
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Actuarial (gain)/loss 47.1us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(22.1)us-gaap_DefinedBenefitPlanActuarialGainLoss
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
Benefits and administrative expenses paid (28.0)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(26.7)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
Ending balance 388.6us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
349.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
380.7us-gaap_DefinedBenefitPlanBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Accumulated benefit obligation 388.6us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
349.7us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
Defined Benefit Plans, Changes in Fair Value of Plan Assets [Roll Forward]      
Fair value of plan assets at beginning of year 268.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
256.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
Actual return on plan assets 15.2us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
28.1us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
Employer contributions 13.8us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
9.9us-gaap_DefinedBenefitPlanContributionsByEmployer
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
Benefits and administrative expenses paid (28.0)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
(26.7)us-gaap_DefinedBenefitPlanBenefitsPaid
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
 
Fair value of plan assets at end of year 269.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
268.1us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
256.8us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Defined Benefit Plans, Weighted Average Assumptions Used in Calculating Benefit Obligations [Abstract]      
Discount rate 4.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
4.80%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
4.00%us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Expected long term rate of return 7.00%lh_DefinedBenefitPlanAssumptionsUsedExpectedLongTermReturnOnAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
7.00%lh_DefinedBenefitPlanAssumptionsUsedExpectedLongTermReturnOnAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
7.00%lh_DefinedBenefitPlanAssumptionsUsedExpectedLongTermReturnOnAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
Defined Benefit Plans, Assets, Target Allocations [Abstract]      
Weighted average expected long-term rate of return for equity securities (in hundredths) 3.50%lh_DefinedBenefitPlanExpectedRateOfReturnOnAssetsEquitySecurities
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Weighted average expected long-term rate of return for fixed income securities (in hundredths) 1.20%lh_DefinedBenefitPlanExpectedRateOfReturnOnAssetsFixedIncomeSecurities
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Weighted average expected long-term rate of return for other assets (in hundredths) 0.30%lh_DefinedBenefitPlanExpectedRateOfReturnOnAssetsOtherAssets
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Defined Benefit Plan, Expected Future Benefit Payments, Year Four 24.6us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
   
Defined Benefit Plan, Expected Future Benefit Payments, Year Five $ 24.9us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember