Share-Based Compensation (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested, beginning of period (in shares)	292,430		292,430		187,140
Nonvested, end of period (in shares)	292,430		292,430		187,140
Share-based compensation expense	$ 252	$ 371	$ 1,708	$ 1,932
Share-based compensation cost capitalized as part of real estate assets	52	37	137	131
Unrecognized compensation cost related to nonvested stock awards	$ 3,190		$ 3,190
Compensation cost to be recognized over a weighted average period			3.2
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, beginning of period (in shares)			447,825
Cancelled (in shares)			(6,600)
Exercised (in shares)			(134,500)
Outstanding, end of period (in shares)	306,725		306,725
Vested and exercisable, end of period (in shares)	306,725		306,725
Weighted average exercise price, outstanding, beginning of period (in dollars per share)	$ 18.26		$ 18.26		$ 16.92
Weighted average exercise price, cancelled (in dollars per share)			$ 18.27
Weighted average exercise price, exercised (in dollars per share)	$ 13.91		$ 13.91
Weighted average exercise price, outstanding, end of period (in dollars per share)	$ 18.26		$ 18.26		$ 16.92
Weighted average exercise price, vested and exercisable, end of period (in dollars per share)	$ 18.26		$ 18.26
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)			179,750
Vested (in shares)			(71,880)
Forfeited (in shares)			(2,580)
Weighted average grant date fair value, nonvested, beginning of period (in dollars per share)	$ 16.09		$ 16.09		$ 18.42
Weighted average grant date fair value, granted (in dollars per share)			$ 17.48
Weighted average grant date fair value, vested (in dollars per share)			$ 25.59
Weighted average grant date fair value, forfeited (in dollars per share)	$ 17.44		$ 17.44
Weighted average grant date fair value, nonvested, end of period (in dollars per share)	$ 16.09		$ 16.09		$ 18.42