Unconsolidated Entities - Summarized Financial Information of Co-Investment Ventures (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Revenues	$ 1,389.6	$ 1,567.4
Net earnings (loss	21.5	49.3
Total assets	17,612.6	20,692.9
Amounts due to us	72.9	76.9
Third party debt	7,192.6	9,290.0
Total liabilities	8,186.7	10,319.3
Noncontrolling interest	8.9	7.9
Co-investment ventures' equity	9,417.0	10,365.7
Our weighted average ownership	25.10%	27.90%
Our investment balance	2,013.1	2,471.2
Deferred gains, net of amortization	329.6	418.7
Americas [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Revenues	759.3	871.8
Net earnings (loss	(72.4)	(23.8)
Total assets	9,070.4	12,236.0
Amounts due to us	31.9	59.5
Third party debt	3,835.5	5,952.8
Total liabilities	4,170.4	6,386.4
Noncontrolling interest	1.4	1.7
Co-investment ventures' equity	4,898.6	5,847.9
Our weighted average ownership	23.20%	28.20%
Our investment balance	1,111.8	1,596.3
Deferred gains, net of amortization	147.9	227.6
Europe [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Revenues	489.8	600.1
Net earnings (loss	85.7	73.6
Total assets	6,605.2	6,211.8
Amounts due to us	33.3	8.1
Third party debt	2,384.2	2,275.8
Total liabilities	2,953.8	2,758.9
Noncontrolling interest	7.5	6.2
Co-investment ventures' equity	3,643.9	3,446.7
Our weighted average ownership	29.70%	29.90%
Our investment balance	722.8	662.0
Deferred gains, net of amortization	181.6	191.0
Asia [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Revenues	140.5	95.5
Net earnings (loss	8.2	(0.5)
Total assets	1,937.0	2,245.1
Amounts due to us	7.7	9.3
Third party debt	972.9	1,061.4
Total liabilities	1,062.5	1,174.0
Co-investment ventures' equity	874.5	1,071.1
Our weighted average ownership	19.20%	19.40%
Our investment balance	178.5	212.9
Deferred gains, net of amortization	$ 0.1	$ 0.1