Fair Value of Financial Instruments and Investments - Investment in CBRE Strategic Partners Asia Measured At Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning Balance, Investment in CBRE Strategic Partners Asia	$ 8,381	$ 9,471
Contributions, Investment in CBRE Strategic Partners Asia	2,029	457
Distributions, Investment in CBRE Strategic Partners Asia	(2,400)	0
Total Loss on Fair Value Adjustment, Investment in CBRE Strategic Partners Asia	(231)	(603)
Translation Adjustment in Other Comprehensive Income, Investment in CBRE Strategic Partners Asia	0	0
Ending Balance, Investment in CBRE Strategic Partners Asia	7,779	9,325
The Amount of Total Income (Loss) for the Period Included in earnings/loss, Investment in CBRE Strategic Partners Asia	(231)	(603)
Beginning Balance, Note Payable	(8,775)	(8,769)
Contributions, Note Payable	0	0
Distributions, Note Payable	0	0
Total Loss on Fair Value Adjustment, Note Payable	(85)	41
Translation Adjustment in Other Comprehensive Income, Note Payable	-348	-12
Ending Balance, Note Payable	(9,208)	(8,740)
The Amount of Total Income (Loss) for the Period Included in earnings/loss, Note Payable	(85)	41
Class B Operating Partnership Unit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning Balance, Note Payable	0
Contributions, Note Payable	0
Distributions, Note Payable	0
Total Loss on Fair Value Adjustment, Note Payable	(200)
Translation Adjustment in Other Comprehensive Income, Note Payable	0
Ending Balance, Note Payable	(200)
The Amount of Total Income (Loss) for the Period Included in earnings/loss, Note Payable	$ (200)