Real Estate (Narrative) (Detail) (USD $)	12 Months Ended									3 Months Ended
	Dec. 31, 2012 Property	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Real Estate Held For Investment [Member]	Dec. 31, 2011 Real Estate Held For Investment [Member]	Dec. 31, 2010 Real Estate Held For Investment [Member]	Dec. 31, 2012 Real Estate Held For Sale [Member]	Dec. 31, 2011 Real Estate Held For Sale [Member]	Dec. 31, 2010 Real Estate Held For Sale [Member]	Dec. 31, 2010 Real Estate Portfolio [Member]	Sep. 30, 2010 Real Estate Portfolio [Member]	Dec. 31, 2010 Real Estate Projects [Member]	Sep. 30, 2010 Real Estate Projects [Member]
Real Estate Properties [Line Items]
Impairment of real estate	$ 26,481,000	$ 4,337,000	$ 26,897,000	$ 17,200,000	$ 1,700,000	$ 24,600,000	$ 9,300,000	$ 2,600,000	$ 2,300,000
Gain on disposition of real estate	683,000	41,805,000	21,248,000							2,300,000	2,800,000	1,800,000	200,000
Subsidiary ownership percentage												5.00%
Deferred gain			100,000
Estimated costs	1,900,000
Number of properties committed for sale	4
Rental revenues	55,600,000	73,900,000	88,500,000
Rental expenses	$ 35,500,000	$ 34,900,000	$ 47,000,000