Other $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) $ / shares shares
Additional Common Shares Authorized | shares	13,000,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased | shares	13,000,000
Stock Repurchased and Retired During Period, Shares | shares	0	0	31,240
Treasury Stock Acquired, Average Cost Per Share | $ / shares			$ 56.87
OP units repurchased and retired	$ 0	$ 0	$ 1,777
Partially Owned Properties Acquired Properties			1
Partially Owned Units Acquired Units			268
Change in Paid In Capital			$ 2,300
Reduction In Partially Owned Properties			2,200
Reduction In Other Liabilities			1,000
Partner Buyout [Member]
Purchase Price, Business Acquisition, Cost of Acquired Entity			$ 5,500
ERPOP [Member]
Stock Repurchased and Retired During Period, Shares | shares	0	0	31,240
OP units repurchased and retired	$ 0	$ 0	$ 1,777
NONCONTROLLING INTERESTS – PARTIALLY OWNED PROPERTIES
Land parcels acquired			1