Line of credit facility potential increase in borrowing capacity.

No definition available.

Name:	md_LineOfCreditFacilityPotentialIncreaseInBorrowingCapacity
Namespace Prefix:	md_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of credit facility, reduction in the available balance

+ References

No definition available.

+ Details

Name:	md_LineOfCreditFacilityReductionInAvailableBalance
Namespace Prefix:	md_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the terms of a credit facility arrangement. Terms typically include interest rate, collateral required, guarantees required, repayment requirements, and restrictions on use of assets and activities of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=md_SwingLineLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=md_TermLoanCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=md_UnsecuredRevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=md_AlternateBaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=md_ApplicableMarginRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
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Long-Term Debt and Capital Lease Obligations - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Oct. 29, 2014	Dec. 31, 2014
Line of Credit Facility [Line Items]
Line of Credit facility, maturity date	Oct. 29, 2019
Line of Credit facility, estimated increase in borrowings		$ 1,800,000,000
Line of credit description		At the Company’s option, borrowings under the Credit Agreement (other than swingline loans) will bear interest at (i) the Alternate Base Rate (defined as the higher of (a) the prime rate, (b) the Federal Funds Rate plus 1/2 of 1.00% and (c) LIBOR for an interest period of one month plus 1.00%) plus an applicable margin rate ranging from 0.125% to 0.750% based on the Company’s consolidated leverage ratio or (ii) the LIBOR rate plus an applicable margin rate ranging from 1.125% to 1.750% based on the Company’s consolidated leverage ratio. Swingline loans will bear interest at the alternate base rate plus the applicable margin.
Line of Credit facility, reduction in the available balance		200,000
Line of Credit facility, available balance		931,800,000
Minimum [Member]
Line of Credit Facility [Line Items]
Commitment fee percentage	0.15%
Maximum [Member]
Line of Credit Facility [Line Items]
Commitment fee percentage	0.30%
Alternate Base Rate [Member]
Line of Credit Facility [Line Items]
Debt instrument, interest rate		1/2 of 1.00%
Alternate Base Rate [Member] \| LIBOR [Member]
Line of Credit Facility [Line Items]
Debt instrument, interest rate		LIBOR for an interest period of one month plus 1.00%
Debt instrument, variable interest rate	1.00%
Applicable Margin Rate [Member] \| LIBOR [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Debt instrument, variable interest rate	0.125%
Applicable Margin Rate [Member] \| LIBOR [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Debt instrument, variable interest rate	0.75%
Unsecured Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit facility, borrowing capacity	1,300,000,000
Term Loan Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit facility, borrowing capacity	200,000,000
Swingline Loans [Member]
Line of Credit Facility [Line Items]
Line of Credit facility, borrowing capacity	75,000,000
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit facility, borrowing capacity	37,500,000