Real Estate and Other Investments - Assets and Liabilities Related to VIEs (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Investment real estate	$ 556,503	$ 587,516
Short-term investments	398,948	206,760
Cash and cash equivalents	436,307	268,164
Other assets	173,040	163,222
Notes payable	159,043	137,963
Other liabilities	483,157	452,985
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Investment real estate	136,355	141,843
Short-term investments	501	500
Cash and cash equivalents	9,633	10,392
Other receivables	4,345	3,939
Other assets	14,439	13,231
Total assets of consolidated VIEs	165,273	169,905
Notes payable	159,043	137,963
Other liabilities	8,841	7,145
Total liabilities of consolidated VIEs	$ 167,884	$ 145,108