Accounts Payable and Accrued Expenses - Additional Information (Detail) $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($)
Payables and Accruals [Abstract]
Net decrease in accrued salaries and bonuses	$ 80.5

Increase decrease in accrued payroll taxes and benefits.

No definition available.

Name:	md_IncreaseDecreaseInAccruedPayrollTaxesAndBenefits
Namespace Prefix:	md_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration