Consolidated Balance Sheets (Parentheticals) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Amortized Cost on Deferred Financing and Leasing Costs $ 173,076,000 $ 169,468,000
Noncontrolling Interest Operating Partnership Common Units Outstanding 3,539,075 3,553,566
Common Stock, Par or Stated Value Per Share $ 0.001 $ 0.001
Common Stock, Shares Authorized 283,987,000 283,987,000
Common Stock, Shares, Issued 150,367,813 149,807,179
Common Stock, Shares, Outstanding 150,367,813 149,807,179
Treasury Stock, Shares 1,249,909 1,249,909
Liberty Property Limited Partnership [Member]    
Amortized Cost on Deferred Financing and Leasing Costs $ 173,076,000 $ 169,468,000
Limited Partners' Capital Account, Units Outstanding 3,539,075 3,553,566
Common Stock, Shares, Outstanding 149,117,904 148,557,270
Treasury Stock, Shares 1,249,909 1,249,909
Series I 2 [Member]    
Temporary Equity, Shares Outstanding 301,483 301,483
Series I 2 [Member] | Liberty Property Limited Partnership [Member]    
Temporary Equity, Shares Outstanding 301,483 301,483