Real Estate Activity - Net Income Attributable to Noncontrolling Interest (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
Income Loss From Operations Net Of Non Controlling Interest [Line Items]
Net income	$ 47,991	$ 27,614	$ 62,244	$ 48,004
Net income, net of noncontrolling interest	47,719	27,488	61,955	47,829
Apartment Communities Sold [Member] | Assets Held-for-sale [Member]
Income Loss From Operations Net Of Non Controlling Interest [Line Items]
Net income	37,356	774	37,493	1,274
Net income, net of noncontrolling interest	$ 37,202	$ 716	$ 37,355	$ 1,219