Impairment Charges and Reserves - Impairment Charges and Reserves Measured at Fair Value on Non-Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Total Impairment Charges	$ 0	$ 0	$ 600	$ 0
Preferred equity interests, Total Impairment Charges			5,733	$ 2,336
Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Fair Value Measurements	800		800
Preferred equity interests, Fair Value Measurements	166,100		166,100
Long-lived assets held and used, Total Impairment Charges			600
Preferred equity interests, Total Impairment Charges			5,700
Fair Value Measurements [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Fair Value Measurements	0		0
Preferred equity interests, Fair Value Measurements	0		0
Fair Value Measurements [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Fair Value Measurements	0		0
Preferred equity interests, Fair Value Measurements	0		0
Fair Value Measurements [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Fair Value Measurements	800		800
Preferred equity interests, Fair Value Measurements	$ 166,100		$ 166,100