Financial Instruments and Fair Value Measurements - Summary of Gains (Losses) From Change in Fair Value of Derivative Instruments Included in Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total gain (loss) on derivative instruments	$ (8,359)	$ 6,037	$ (26,380)	$ 53,272
Total gain (loss) on derivative and non-derivative instruments	7,491	6,037	(16,060)	53,272
Derivative net investment hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total gain (loss) on derivative instruments	(6,195)	(528)	(23,109)	34,196
Interest rate swap hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total gain (loss) on derivative instruments	(187)	955	(190)	892
Our share of derivatives from unconsolidated co-investment ventures [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total gain (loss) on derivative instruments	(1,977)	5,610	(3,081)	18,184
Non-derivative net investment hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Non-derivative net investment hedges	$ 15,850		$ 10,320