Impairment Charges and Reserves - Impairment Charges Measured at Fair Value on Non-Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reserve of preferred equity interests, Total Losses	$ 76,000	$ 0
Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Reserve of preferred equity interests, Fair Value Measurements	319,300
Long-lived assets held and used, Fair Value Measurements	14,800		$ 438,200
Long-lived assets held and used, Total Losses	22,000		110,900
Reserve of 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
Reserve of 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		0
Reserve of 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	14,800		$ 438,200
Reserve of preferred equity interests, Fair Value Measurements	$ 319,300