Leasing Activities - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015 Restaurants	Mar. 31, 2014 Restaurants
Operating Leased Assets [Line Items]
Number of restaurants leased to Del Taco	3	3
Number of properties subleased to Del Taco franchisee	1
Number of lease years	32 years
Percentage of gross sales of restaurants	12.00%
Leases expiration period	2021 to 2022
Minimum rentals due to partnership	$ 3,500
Number of restaurants operated	2
Combined unaudited sales	612,864	581,837
Combined unaudited net income (losses)	10,344	(4,402)
Del Taco franchisee [Member]
Operating Leased Assets [Line Items]
Number of restaurants operated	1
Combined unaudited sales	$ 369,454	$ 332,515