Share-Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Stock Awards [Member]	Dec. 31, 2012 Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	10,400,000		10,400,000
Share-based compensation expense	$ 418	$ 467	$ 2,296	$ 1,974
Share-based compensation cost capitalized as part of real estate assets	54	45	159	96
Unrecognized compensation cost related to nonvested stock awards	$ 5,468		$ 5,468
Compensation cost to be recognized over a weighted average period			3 years 8 months
Nonvested, beginning of period (in shares)					338,370,000	346,860,000
Granted (in shares)					210,650,000
Vested (in shares)					(209,270,000)
Forfeited (in shares)					(9,870,000)
Nonvested, end of period (in shares)					338,370,000	346,860,000
Weighted average grant date fair value, nonvested, beginning of period (in dollars per share)					$ 19.20	$ 17.06
Weighted average grant date fair value, granted (in dollars per share)					$ 21.91
Weighted average grant date fair value, vested (in dollars per share)					$ 18.41
Weighted average grant date fair value, forfeited (in dollars per share)					$ 18.32
Weighted average grant date fair value, nonvested, end of period (in dollars per share)					$ 19.20	$ 17.06