Indebtedness (Debt compliance and other) - Additional Information (Detail) - 6 months ended Jun. 30, 2015	Total
Debt Disclosure [Abstract]
Coverage's ratio	1.5
Company's ratio	2.0
Unencumbered assets to unsecured debt	1.5
Leverage ratio	60.00%
Total secured debt to total asset value	40.00%
Line of credit facility, covenant terms	The Company's Syndicated Line, Cash Management Line, Term Loan and senior unsecured notes contain customary restrictions, representations, covenants and events of default and require the Company to meet certain financial covenants. Debt service and fixed charge coverage covenants require the Company to maintain coverages of a minimum of 1.5 to 1.0, as defined in applicable debt arrangements.