Business Segments - Segment Reporting, Reconciliation of Revenues, Operating Income and Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total revenues	$ 490,616	$ 479,430
Consolidated net earnings (loss)	296,932	213,097
General and administrative expenses	(56,197)	(60,159)
Depreciation and amortization expense	(177,266)	(180,280)
Merger, acquisition and other integration expenses		(10,728)
Impairment of real estate properties		(3,185)
Earnings from unconsolidated entities, net	24,768	13,995
Interest expense	(115,028)	(133,056)
Interest and other income, net	11,627	5,101
Gains on acquisitions and dispositions of investments in real estate, net	338,845	267,771
Foreign currency and derivative gains (losses), net	884	(26,775)
Gains (losses) on early extinguishment of debt, net	(17,351)	5,419
Impairment of goodwill and other assets		(16,135)
Earnings before income taxes	342,717	201,451
Investments in and advances to other unconsolidated entities	3,635,214		2,195,782
Notes receivable backed by real estate	188,000		188,000
Assets held for sale	25,391		26,027
Cash and cash equivalents	785,359	343,736	100,810	176,072
Other assets	206,045		188,473
Total reconciling items	4,840,009		2,699,092
Total assets	24,075,299		27,310,145
Real estate operations [Member]
Segment Reporting Information [Line Items]
Total revenues	456,981	447,073
Consolidated net earnings (loss)	318,709	324,007
Total assets	19,146,435		24,519,306
Private capital [Member]
Segment Reporting Information [Line Items]
Total revenues	33,635	32,357
Consolidated net earnings (loss)	13,726	15,476
Total assets	88,855		91,747
Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated net earnings (loss)	332,435	339,483
Total assets	19,235,290		24,611,053
Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated net earnings (loss)	10,282	(138,032)
Americas [Member] | Real estate operations [Member]
Segment Reporting Information [Line Items]
Total revenues	316,809	281,777
Consolidated net earnings (loss)	221,561	198,489
Total assets	15,222,230		15,304,053
Americas [Member] | Private capital [Member]
Segment Reporting Information [Line Items]
Total revenues	16,187	18,354
Consolidated net earnings (loss)	2,883	7,947
Total assets	24,035		24,373
Europe [Member] | Real estate operations [Member]
Segment Reporting Information [Line Items]
Total revenues	99,467	111,676
Consolidated net earnings (loss)	67,206	84,044
Total assets	2,167,953		5,738,257
Europe [Member] | Private capital [Member]
Segment Reporting Information [Line Items]
Total revenues	10,613	9,137
Consolidated net earnings (loss)	6,871	5,384
Total assets	59,777		61,266
Asia [Member] | Real estate operations [Member]
Segment Reporting Information [Line Items]
Total revenues	40,705	53,620
Consolidated net earnings (loss)	29,942	41,474
Total assets	1,756,252		3,476,996
Asia [Member] | Private capital [Member]
Segment Reporting Information [Line Items]
Total revenues	6,835	4,866
Consolidated net earnings (loss)	3,972	2,145
Total assets	$ 5,043		$ 6,108