Schedule III Real Estate and Accumulated Depreciation - Activity in Real Estate Facilities (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Real estate facilities
Balance at beginning of year	$ 604,727,895		$ 510,395,576
Facility acquisitions	74,743,745		85,722,709
Impact of foreign exchange rate changes	(2,415,103)
Improvements	17,082,250		9,670,749
Balance at end of year	694,138,787	[1]	604,727,895
Accumulated depreciation
Balance at beginning of year	29,840,320
Depreciation expense	16,591,835		13,869,032
Balance at end of year	46,432,155		29,840,320
Real estate facilities, net	$ 648,483,436		$ 580,121,001

[1] The aggregate cost of real estate for United States federal income tax purposes is $761,130,955.