Other assets Other assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Acquired below-market ground leases	$ 12,741	$ 12,913
Acquired in-place leases	66,188	63,408
Deferred compensation plan	14,832	11,632
Deferred financing costs – $1.65 billion unsecured senior line of credit	11,453	14,239
Deposits	3,592	3,302
Furniture, fixtures, and equipment	11,443	12,839
Interest rate hedge assets	3,733	4,115
Net investment in direct financing lease	38,057	37,297
Notes receivable	635	694
Prepaid expenses	11,329	9,724
Property, plant, and equipment	27,263	19,891
Other assets	11,790	11,143
Total	$ 213,056	$ 201,197