Sales by Channel (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Net Revenue	$ 73,364,000	$ 79,233,000
Medifast Direct
Segment Reporting Information [Line Items]
Net Revenue	14,426,000	17,144,000
Take Shape For Life
Segment Reporting Information [Line Items]
Net Revenue	52,102,000	56,966,000
Medifast Weight Control Centers- Franchise
Segment Reporting Information [Line Items]
Net Revenue	4,681,000	3,588,000
Medifast Wholesale
Segment Reporting Information [Line Items]
Net Revenue	$ 2,155,000	$ 1,535,000