Fair Value of Financial Instruments (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013	Mar. 31, 2013
Fair Value Disclosures [Abstract]
Notes and bonds payable, Carrying value	$ 1,388,241,000		$ 1,348,459,000	$ 1,348,459,000
Mortgage notes receivable, Carrying value	86,372,000		125,547,000	125,547,000
Notes receivable, net of allowances, Carrying value	100,000			100,000
Notes and bonds payable, Fair value	1,404,600,000	[1]		1,380,600,000	[1]
Mortgage notes receivable, Fair value	86,400,000	[2]		124,500,000	[2]
Notes receivable, net of allowances, Fair value	$ 100,000	[2]		$ 100,000	[2]

[1] Level 3 - Fair value derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.

[2] Level 2 - Fair value based on quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which significant inputs and significant value drivers are observable in active markets.