Real Estate Facilities (Activity In Real Estate Facilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Balances	$ 1,985,065	$ 1,991,959	$ 1,933,319
Acquisition of real estate facilities		46,298	116,610
Capital expenditures	46,777	54,462	60,228
Depreciation and amortization	(105,394)	(110,357)	(108,917)
Transfer to properties sold	33	2,703	6,138
Transfer to land and building held for development			(15,419)
Balances	1,926,481	1,985,065	1,991,959
Land [Member]
Property, Plant and Equipment [Line Items]
Balances	$ 793,569	772,161	738,421
Acquisition of real estate facilities		$ 21,408	$ 39,667
Capital expenditures
Disposals
Depreciation and amortization
Transfer to properties sold
Transfer to land and building held for development			$ (5,927)
Balances	$ 793,569	$ 793,569	772,161
Building And Improvements [Member]
Property, Plant and Equipment [Line Items]
Balances	2,182,993	2,115,987	2,005,943
Acquisition of real estate facilities		24,890	76,943
Capital expenditures	46,777	54,462	60,228
Disposals	(13,990)	(10,587)	(15,391)
Transfer to properties sold	(265)	(1,759)	(1,466)
Transfer to land and building held for development			(10,270)
Balances	2,215,515	2,182,993	2,115,987
Accumulated Depreciation [Member]
Property, Plant and Equipment [Line Items]
Balances	(991,497)	(896,189)	(811,045)
Disposals	13,990	10,587	15,391
Depreciation and amortization	(105,394)	(110,357)	(108,917)
Transfer to properties sold	298	4,462	7,604
Transfer to land and building held for development			778
Balances	$ (1,082,603)	$ (991,497)	$ (896,189)