Impairment Charges and Reserves - Impairment Charges Measured at Fair Value on Non-Recurring Basis (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-lived assets held and used, Fair Value Measurements	$ 452,700
Assets included in the spin-off of RVI, Fair Value Measurements	624,600
Preferred equity interests, Fair Value Measurements	199,300
Preferred equity interests, Total Losses	4,537	$ 60,623
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	452,700
Assets included in the spin-off of RVI, Fair Value Measurements	624,600
Preferred equity interests, Fair Value Measurements	199,300
Long-lived assets held and used, Total Losses	54,300
Assets included in the spin-off of RVI, Total Losses	14,100
Preferred equity interests, Total Losses	4,500
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
Assets included in the spin-off of RVI, Fair Value Measurements	0
Preferred equity interests, Fair Value Measurements	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
Assets included in the spin-off of RVI, Fair Value Measurements	0
Preferred equity interests, Fair Value Measurements	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	452,700
Assets included in the spin-off of RVI, Fair Value Measurements	624,600
Preferred equity interests, Fair Value Measurements	$ 199,300