Impairment Charges and Impairment of Joint Venture Investments - Impairment Charges on Assets or Investments (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Impairment Charges And Impairment Of Joint Venture Investments [Abstract]
Land held for development	$ 0	$ 0	$ 13,200,000	$ 0
Undeveloped land	1,400,000	0	1,900,000	2,600,000
Assets marketed for sale	400,000	9,200,000	3,800,000	20,300,000
Total continuing operations	1,813,000	9,260,000	18,898,000	22,902,000
Sold assets – discontinued operations	0	14,875,000	8,098,000	43,893,000
Joint venture investments	0	0	9,100,000	0
Total impairment charges	$ 1,800,000	$ 24,100,000	$ 36,100,000	$ 66,800,000