CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Parent	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Noncontrolling Interest
Balance at Dec. 31, 2012	$ 1,070,256	$ 622,797	$ 52	$ 581,925	$ (4,307)	$ 45,127	$ 447,459
Balance (in Shares) at Dec. 31, 2012	52,482,598		52,482,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)			92,000
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0	1,548	0	1,548	0	0	(1,548)
Issuance of Common Shares, net of issuance costs (in Shares)			2,822,000
Issuance of Common Shares, net of issuance costs	75,765	75,765	3	75,762	0	0	0
Issuance of OP Units to Acquire Real Estate	0
Dividends declared	(35,712)	(34,698)	0	0	0	(34,698)	(1,014)
Vesting of employee Restricted Share and LTIP awards (in Shares)			53,000
Vesting of employee Restricted Share and LTIP awards	4,592	925	0	925	0	0	3,667
Acquisition Of Interest In Unconsolidated Affiliate Investment In Unconsolidated Affiliates	(33,949)	0	0	0	0	0	(33,949)
Noncontrolling interest distributions	(29,623)	0	0	0	0	0	(29,623)
Noncontrolling Interest, Increase from Contributions	27,515	0	0	0	0	0	27,515
Balance before adjustment towards comprehensive income (in Shares)			55,449,000
Balance before adjustment towards comprehensive income	1,078,844	666,337	55	660,160	(4,307)	10,429	412,507
Comprehensive (loss) income:
Net income	29,933	27,865	0	0	0	27,865	2,068
Unrealized (loss) income on valuation of swap agreements	2,247	2,173	0	0	2,173	0	74
Reclassification of realized interest on swap agreements	2,132	1,388	0	0	1,388	0	744
Total comprehensive (loss) income	34,312	31,426	0	0	3,561	27,865	2,886
Balance at Sep. 30, 2013	$ 1,113,156	$ 697,763	$ 55	$ 660,160	$ (746)	$ 38,294	$ 415,393
Balance (in Shares) at Sep. 30, 2013	55,448,856		55,449,000