Deferred Financing and Leasing Costs (Deferred Financing and Leasing Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-lived intangible assets
Deferred financing costs	$ 17,044	$ 11,917
Deferred leasing costs	198,767	179,161
Market value intangible	18,802	19,451
Origination value intangible	90,116	83,485
Finite-lived intangible assets, gross	324,729	294,014
Accumulated amortization:
Deferred financing costs	(11,002)	(10,152)
Deferred leasing costs	(80,434)	(70,842)
Market value intangible	(14,324)	(12,625)
Origination value intangible	(59,719)	(53,357)
Finite-lived intangible assets, accumulated amortization	(165,479)	(146,976)
Deferred financing and leasing costs, net	159,250	147,038
Amortization of deferred financing costs	3,750	3,974	$ 4,395
Amortization of intangible assets	$ 31,600	$ 37,100	$ 44,200