Impairment Charges and Reserves - Impairment Charges Measured at Fair Value on Non-Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred equity interests, Total Losses	$ 0	$ 76,000	$ 0
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	59,500	59,500
Preferred equity interests, Fair Value Measurements	319,300	319,300
Long-lived assets held and used, Total Losses		50,100
Preferred equity interests, Total Losses		76,000
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	59,500	59,500
Preferred equity interests, Fair Value Measurements	$ 319,300	$ 319,300