Business Segments - Segment Reporting, Reconciliation of Revenues, Operating Income and Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 772,052	$ 693,656
Operating income	376,590	432,218
General and administrative expenses	69,701	62,428
Depreciation and amortization expenses	284,009	204,081
Gains on real estate transactions, net	188,208	195,111
Earnings from unconsolidated entities, net	56,666	62,656
Interest expense	(60,507)	(47,245)
Interest and other income, net	7,910	1,976
Foreign currency and derivative gains (losses), net	8,734	(41,094)
Losses on early extinguishment of debt, net	(2,116)	0
Earnings before income taxes	387,277	408,511
Total assets	38,392,112			$ 38,417,664
Investments in and advances to unconsolidated entities	5,613,060			5,745,294
Assets held for sale or contribution	899,976			622,288
Lease right-of-use assets	383,704		$ 393,000	0
Cash and cash equivalents	251,030	458,099		343,856	$ 447,046
Other assets	1,717,255			1,775,919
Real Estate Operations [Member]
Segment Reporting Information [Line Items]
Total assets	31,220,991			31,431,376
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating income	542,092	503,616
Total assets	31,262,122			31,472,913
Operating Segments [Member] | Real Estate Operations [Member]
Segment Reporting Information [Line Items]
Total revenues	698,247	560,695
Operating income	506,345	414,515
Operating Segments [Member] | Strategic Capital [Member]
Segment Reporting Information [Line Items]
Total revenues	73,805	132,961
Operating income	35,747	89,101
Total assets	41,131			41,537
Operating Segments [Member] | U.S. [Member] | Real Estate Operations [Member]
Segment Reporting Information [Line Items]
Total revenues	651,869	499,257
Operating income	471,076	369,364
Total assets	28,113,087			27,666,200
Operating Segments [Member] | U.S. [Member] | Strategic Capital [Member]
Segment Reporting Information [Line Items]
Total revenues	20,268	16,069
Operating income	3,327	(4,236)
Total assets	15,483			15,802
Operating Segments [Member] | Other Americas [Member] | Real Estate Operations [Member]
Segment Reporting Information [Line Items]
Total revenues	23,865	30,431
Operating income	19,053	22,923
Total assets	1,185,389			1,712,862
Operating Segments [Member] | Other Americas [Member] | Strategic Capital [Member]
Segment Reporting Information [Line Items]
Total revenues	7,900	6,153
Operating income	5,422	2,907
Operating Segments [Member] | Europe [Member] | Real Estate Operations [Member]
Segment Reporting Information [Line Items]
Total revenues	8,557	17,202
Operating income	5,544	12,459
Total assets	1,158,984			1,040,061
Operating Segments [Member] | Europe [Member] | Strategic Capital [Member]
Segment Reporting Information [Line Items]
Total revenues	28,838	38,817
Operating income	19,151	27,663
Total assets	25,280			25,280
Operating Segments [Member] | Asia [Member] | Real Estate Operations [Member]
Segment Reporting Information [Line Items]
Total revenues	13,956	13,805
Operating income	10,672	9,769
Total assets	763,531			1,012,253
Operating Segments [Member] | Asia [Member] | Strategic Capital [Member]
Segment Reporting Information [Line Items]
Total revenues	16,799	71,922
Operating income	7,847	62,767
Total assets	368			455
Reconciling Items [Member]
Segment Reporting Information [Line Items]
Operating income	376,590	432,218
General and administrative expenses	(69,701)	(62,428)
Depreciation and amortization expenses	(284,009)	(204,081)
Gains on real estate transactions, net	188,208	195,111
Earnings from unconsolidated entities, net	56,666	62,656
Interest expense	(60,507)	(47,245)
Interest and other income, net	7,910	$ 1,976
Total assets	7,129,990			6,944,751
Investments in and advances to unconsolidated entities	5,613,060			5,745,294
Assets held for sale or contribution	899,976			622,288
Lease right-of-use assets	116,012			0
Cash and cash equivalents	251,030			343,856
Other assets	$ 249,912			$ 233,313