Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands		12 Months Ended
	Mar. 10, 2014	Dec. 31, 2015
Land Improvements
Business Acquisition [Line Items]
Estimated useful lives		10 years
San Rafael Corporate Center
Business Acquisition [Line Items]
Building and improvements	$ 94,414
Land	14,565
Land improvements	3,616
Intangible assets	3,905
Net identifiable assets acquired	$ 116,500
Estimated useful lives		Remaining lease terms
San Rafael Corporate Center | Building and Improvements
Business Acquisition [Line Items]
Estimated useful lives	50 years
San Rafael Corporate Center | Land Improvements
Business Acquisition [Line Items]
Estimated useful lives	10 years