Real Estate and Other Investments - Assets and Liabilities Related to VIEs (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Investment real estate	$ 582,756	$ 587,516
Short-term investments	597,183	206,760
Cash and cash equivalents	312,835	268,164
Other assets	181,627	163,222
Notes payable	159,577	137,963
Other liabilities	428,155	452,985
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Investment real estate	135,235	141,843
Short-term investments	501	500
Cash and cash equivalents	10,697	10,392
Other receivables	3,721	3,939
Other assets	12,261	13,231
Total assets of consolidated VIEs	162,415	169,905
Notes payable	159,577	137,963
Other liabilities	4,755	7,145
Total liabilities of consolidated VIEs	$ 164,332	$ 145,108