Summary of Components of Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Stockholders Equity Note [Line Items]
Net unrealized gains on real estate securities	$ 109,190	$ 137,360
Less: Unrealized losses attributable to noncontrolling interest		(4,164)
Net unrealized gains on real estate securities recognized in equity	109,190	141,524
Net unrealized losses on interest rate agreements accounted for as cash flow hedges	(28,569)	(29,185)
Total Accumulated Other Comprehensive Income	$ 80,621	$ 112,339