Debt - Covenants - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2016	Sep. 30, 2016
Debt Instrument [Line Items]
Percentage of dividends which could be paid from adjusted operating funds	95.00%
Percentage of dividends which could be paid from operation funds	95.00%
Maximum percentage of total unencumbered assets	150.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unsecured leverage ratio	77.50%
Scenario, Forecast [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unsecured leverage ratio		65.00%