Equity and Stock-Based Compensation (Distribution of REIT Taxable Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of Distribution of Taxable Income
Common and preferred dividends paid	$ 31,655	$ 31,557	$ 49,365
Dividends treated as taxable compensation	(147)	(71)	(79)
Portion of dividends declared in current year, and paid in current year, which was applied to the prior year distribution requirements	0	(304)	(1,606)
Portion of dividends declared in subsequent year, and paid in subsequent year, which apply to current year distribution requirements	1,563	(10)	304
Dividends applied to meet current year REIT distribution requirements	$ 33,071	$ 31,172	$ 47,984