Schedule III - Real Estate and Accumulated Depreciation (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 0
Initial cost to company, Land & land improvements	1,852,482
Initial cost to company, Building & Improvements	1,013,134
Cost capitalized subsequent to acquisition, Carrying costs	77,203
Gross amount at which carried at close of period Land, buildings & improvements, Total	2,942,819	2,942,819	2,942,819	2,942,819
Accumulated depreciation	1,143,645	1,114,697	1,085,749	1,056,801
Rialto, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost to company, Land & land improvements	274,837
Initial cost to company, Building & Improvements	150,310
Gross amount at which carried at close of period Land, buildings & improvements, Total	425,147
Accumulated depreciation	169,675
Date of construction	1984
Date acquired	1984
Moreno Valley, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost to company, Land & land improvements	353,557
Initial cost to company, Building & Improvements	193,362
Gross amount at which carried at close of period Land, buildings & improvements, Total	546,919
Accumulated depreciation	218,271
Date of construction	1985
Date acquired	1985
La Verne, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost to company, Land & land improvements	452,423
Initial cost to company, Building & Improvements	247,433
Gross amount at which carried at close of period Land, buildings & improvements, Total	699,856
Accumulated depreciation	279,306
Date of construction	1985
Date acquired	1985
Rancho Cucamonga, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost to company, Land & land improvements	293,817
Initial cost to company, Building & Improvements	160,690
Cost capitalized subsequent to acquisition, Carrying costs	77,203
Gross amount at which carried at close of period Land, buildings & improvements, Total	531,710
Accumulated depreciation	181,383
Date of construction	1985
Date acquired	1985
Sacramento, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost to company, Land & land improvements	260,516
Initial cost to company, Building & Improvements	142,478
Gross amount at which carried at close of period Land, buildings & improvements, Total	402,994
Accumulated depreciation	160,834
Date of construction	1985
Date acquired	1985
Rancho Cucamonga, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Initial cost to company, Land & land improvements	217,332
Initial cost to company, Building & Improvements	118,861
Gross amount at which carried at close of period Land, buildings & improvements, Total	336,193
Accumulated depreciation	$ 134,176
Date of construction	1985
Date acquired	1985
Land & land improvements [Member] | Rialto, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	20 years
Land & land improvements [Member] | Moreno Valley, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	20 years
Land & land improvements [Member] | La Verne, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	20 years
Land & land improvements [Member] | Rancho Cucamonga, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	20 years
Land & land improvements [Member] | Sacramento, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	20 years
Land & land improvements [Member] | Rancho Cucamonga, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	20 years
Buildings and improvements [Member] | Rialto, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	35 years
Buildings and improvements [Member] | Moreno Valley, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	35 years
Buildings and improvements [Member] | La Verne, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	35 years
Buildings and improvements [Member] | Rancho Cucamonga, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	35 years
Buildings and improvements [Member] | Sacramento, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	35 years
Buildings and improvements [Member] | Rancho Cucamonga, CA [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	35 years