Notes and Bonds Payable (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Debt Instrument [Line Items]
Notes and bonds payable	$ 1,293,044	[1]	$ 1,393,537	[1]
Senior Notes [Member] | 6.500% Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Senior notes face value	300,000		300,000
Unaccreted discount	(1,272)		(1,535)
Notes and bonds payable	$ 298,728		$ 298,465

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