Changes in Real Estate Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Real Estate And Accumulated Depreciation Disclosure [Abstract]
Beginning balance	$ 591,136	$ 450,250
Purchase of real estate investments	82,111	143,141
Sale and disposal of investment property	(1,325)	(2,255)
Property held for sale	(2,058)
Provision for asset impairment	(412)	0
Reallocation to intangible assets	32
Ending balance	$ 669,484	$ 591,136