Financial Instruments and Fair Value Measurements - Fair Value Measurements on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value Assets Measured On Recurring Basis [Line Items]
Real estate assets	$ 3,677,365	$ 122,088
Investments in and advances to other unconsolidated entities		26,066
Level 1 [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Real estate assets
Investments in and advances to other unconsolidated entities
Level 2 [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Real estate assets
Investments in and advances to other unconsolidated entities
Level 3 [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Real estate assets	3,677,365	122,088
Investments in and advances to other unconsolidated entities		$ 26,066